Please use this identifier to cite or link to this item: https://hdl.handle.net/11681/19336
Title: Use of Natural and Nature-Based Features (NNBF) for coastal resilience
Authors: Bridges, Todd S.; Burks-Copes, Kelly A.; Bates, Matthew E.; Collier, Zachary A.; Fischenich, J. Craig; Piercy, Candice D.; Russo, Edmond J.; Shafer, Deborah J.; Suedel, Burton C.; Gailani, Joseph Z.; Rosati, Julie Dean; Wamsley, Ty V.; Wagner, Paul W.; Leuck, Lauren D.; Vuxton, Emily A.;
Keywords: Storm surges; Ocean waves; Coastal sediments; Sediment control;
Publisher: U.S. Army Engineer Research and Development Center, Environmental Laboratory, Coastal and Hydraulics Laboratory
Description: ERDC SR-15-1 Use of Natural and Nature-Based Features (NNBF) for Coastal Resilience Final Report Engineer Research and Development Center Todd S. Bridges, Paul W. Wagner, Kelly A. Burks-Copes, Matthew E. Bates, Zachary A. Collier, Craig J. Fischenich, Joe Z. Gailani, Lauren D. Leuck, Candice D. Piercy, Julie D. Rosati, Edmond J. Russo, Deborah J. Shafer, Burton C. Suedel, Emily A. Vuxton, and Ty V. Wamsley January 2015 Approved for public release; distribution is unlimited. The US Army Engineer Research and Development Center (ERDC) solves the nation’s toughest engineering and environmental challenges. ERDC develops innovative solutions in civil and military engineering, geospatial sciences, water resources, and environmental sciences for the Army, the Department of Defense, civilian agencies, and our nation’s public good. Find out more at www.erdc.usace.army.mil. To search for other technical reports published by ERDC, visit the ERDC online library at http://acwc.sdp.sirsi.net/client/default. ERDC SR-15-1 January 2015 Use of Natural and Nature-Based Features (NNBF) for Coastal Resilience Final Report Todd S. Bridges, Kelly A. Burks-Copes, Matthew E. Bates, Zachary Collier, Craig J. Fischenich, Candice D. Piercy, Edmond J. Russo, Deborah J. Shafer, and Burton C. Suedel Environmental Laboratory U.S. Army Engineer Research and Development Center 3909 Halls Ferry Road Vicksburg, MS 31980-6199 Joe Z. Gailani, Julie D. Rosati, and Ty V. Wamsley Coastal and Hydraulic Laboratory U.S. Army Engineer Research and Development Center 3909 Halls Ferry Road Vicksburg, MS 31980-6199 Paul W. Wagner, Lauren D. Leuck, and Emily A. Vuxton U.S. Army Corps of Engineers, Institute of Water Resources 7701 Telegraph Road Alexandria, VA 22153 Final report Approved for public release; distribution is unlimited. Prepared for U.S. Army Corps of Engineers Washington, DC 20314-1000 Monitored by Environmental Laboratory U.S. Army Engineer Research and Development Center 3909 Halls Ferry Road, Vicksburg, MS 39180-6199 ERDC SR-15-1 ii Abstract Coastal systems are increasingly vulnerable to flooding due to the combined influence of coastal storms, development and population growth, geomorphic change, and sea level rise. This reality has given rise to efforts to make greater use of ecosystem-based approaches to reduce risks from coastal storms, approaches which draw from the capacity of wetlands, beaches and dunes, biogenic reefs, and other natural features to reduce the impacts of storm surge and waves. This report offers details regarding the use of natural and nature-based features (NNBF) to improve coastal resilience and was designed to support post-Hurricane Sandy recovery efforts under the North Atlantic Coast Comprehensive Study (NACCS). An integrative framework is offered herein that focuses on classifying NNBF, characterizing vulnerability, developing performance metrics, incorporating regional sediment management, monitoring and adaptively managing from a systems perspective, and addressing key policy challenges. As progress is made on these and other actions across the many organizations contributing to the use of NNBF, implementation of the full array of measures available will reduce the risks and enhance the resilience of the region's coastal systems. DISCLAIMER: The contents of this report are not to be used for advertising, publication, or promotional purposes. Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products. All product names and trademarks cited are the property of their respective owners. The findings of this report are not to be construed as an official Department of the Army position unless so designated by other authorized documents. DESTROY THIS REPORT WHEN NO LONGER NEEDED. DO NOT RETURN IT TO THE ORIGINATOR. ERDC SR-15-1 iii Contents Abstract ......................................................................................................................................................... ii Figures and Tables ......................................................................................................................................vii Preface .......................................................................................................................................................... xv Executive Summary ...................................................................................................................................xvi Unit Conversion Factors ........................................................................................................................ xxvii Acronyms ................................................................................................................................................ xxviii 1 An Introduction to Natural and Nature-Based Features (NNBF) and Their Use in Coastal Systems ................................................................................................................................... 1 Overview .................................................................................................................................. 1 Natural and nature-based features (NNBF) ................................................................................ 6 Dynamic character of NNBF ........................................................................................................ 8 Performance with respect to objectives ..................................................................................... 9 Engineering With Nature (EWN) using NNBF ............................................................................ 10 The role of sound science and engineering.............................................................................. 10 A framework for NNBF evaluation and implementation....................................................... 11 Looking forward ...................................................................................................................... 13 2 NNBF Classification, Mapping, and Feature Characterization .................................................. 14 Overview ................................................................................................................................ 14 How to use these classification systems .............................................................................. 15 Geomorphologic classification .............................................................................................. 15 Background to coastal classification ........................................................................................ 15 Atlantic Coast classification from Chesapeake Bay to central Maine ..................................... 16 Geomorphic features found along coast types ..................................................................... 27 Geomorphic feature descriptions (NNBF Categories) .............................................................. 28 Costs associated with the feature construction for NNBF ....................................................... 37 Processes that drive feature form and function ................................................................... 37 Geometric characteristics .......................................................................................................... 39 Hydrodynamic and meteorological characteristics .................................................................. 41 Sedimentary characteristics ...................................................................................................... 43 Biophysical characteristics ........................................................................................................ 45 Conclusions ............................................................................................................................ 46 3 Coastal Vulnerability and Resilience Metrics for NNBF .............................................................. 48 Introduction ............................................................................................................................ 48 Vulnerability ............................................................................................................................ 49 Components of vulnerability ...................................................................................................... 51 Risk versus vulnerability ............................................................................................................ 53 ERDC SR-15-1 iv Resilience versus vulnerability .................................................................................................. 54 Review of selected previously developed coastal vulnerability metrics .............................. 57 Vulnerability metrics development process .......................................................................... 63 Step 1: Identify purpose ............................................................................................................. 63 Step 2: Describe vulnerability profile ........................................................................................ 64 Step 3: Define system components and valued functions ...................................................... 65 Step 4: Link factors to functions ............................................................................................... 67 Step 5: Establish metrics ........................................................................................................... 69 Vulnerability metrics for coastal landscapes ........................................................................ 71 Marine Depositional Barrier Coast (II B 1) vulnerability metrics ............................................. 72 Specific NNBF vulnerability metrics .......................................................................................... 74 Vulnerability metrics discussion ................................................................................................ 76 A community self-assessment of resilience ......................................................................... 78 Examples of community self-assessments ............................................................................... 79 Steps in the community’s self-assessment .............................................................................. 82 Measures to increase community resilience ............................................................................ 91 Conclusions ............................................................................................................................ 92 4 Performance Metrics for Ecosystem Goods and Services Generated by NNBF and Structural Features in the Post-Sandy Environment.................................................................... 94 Introduction ............................................................................................................................ 94 Coming to terms with the science and practice ....................................................................... 95 Ecosystem goods and services ................................................................................................. 96 Typologies .................................................................................................................................. 99 Performance metrics ............................................................................................................... 101 Key take-home messages ........................................................................................................ 104 Methods ............................................................................................................................... 105 Results ................................................................................................................................. 107 Features of concern ................................................................................................................. 108 Ecosystem goods and services considered ............................................................................ 109 Decomposition ......................................................................................................................... 113 Three levels of characterization .............................................................................................. 116 Conclusions .......................................................................................................................... 140 5 Framework for Assessing and Ranking NNBF Alternatives .................................................... 142 Introduction .......................................................................................................................... 142 Structured decision-making process ................................................................................... 143 Basic framework construct .................................................................................................. 144 Stakeholder preference surveys .......................................................................................... 145 Framework construct across tiers ....................................................................................... 145 Example matrix ..................................................................................................................... 147 Structured decision-making framework case study application ........................................ 152 Example objective addressed through the tiered framework ............................................ 159 Tier 1: Semi-quantitative .......................................................................................................... 159 Tier 2: Existing data ................................................................................................................. 161 Tier 3: Quantitative data and models...................................................................................... 162 Framework attributes ........................................................................................................... 165 ERDC SR-15-1 v 6 Regional Sediment Management (RSM) Strategy for Beneficial Use of Dredged Materials (BUDM) on Construction of NNBF .............................................................................. 167 Introduction .......................................................................................................................... 167 Preparatory tasks ................................................................................................................. 168 Present BUDM practice............................................................................................................ 168 Definition of terms ................................................................................................................... 169 Literature review ...................................................................................................................... 169 Description of the Dredged Material Management Decisions Model (D2M2) ..................... 171 Screening methodology for SMSP ....................................................................................... 173 NNBF opportunity identification .............................................................................................. 174 Navigation channel operations and maintenance sediment source estimation .................. 181 An inventory of options for matching sediment sources with BUDM opportunities ............. 184 Stakeholder involvement and development and selection of dredged sediments strategic placement designs................................................................................................ 187 Identification of interested and affected parties .................................................................... 187 A decision framework for structuring stakeholder engagement ........................................... 187 An example framework for stakeholder engagement in the LIS DMMP ............................... 189 Optimization of dredged sediment management with respect to multiple objectives ......... 192 Long Island Sound (LIS) Dredged Materials Management Plan (DMMP) D2M2 Demonstration ...................................................................................................................... 193 LIS input data development .................................................................................................... 193 Optimization sediment management planning ...................................................................... 196 Results and discussion ........................................................................................................ 198 7 Ecosystem Service Benefits of USACE Ecological Restoration Projects in the Coastal Northeast: Hurricane Sandy Case Study ...................................................................... 202 Introduction ..........................................................................................................................202 Case study: Restoration site descriptions .............................................................................. 205 Measuring economic values or social benefits ...................................................................... 209 Analysis ................................................................................................................................ 211 Steps 1 and 2: Identify ecosystem goods and services of interest and choose benefit indicators ..................................................................................................................... 211 Step 3. Quantifying biophysical changes ................................................................................ 214 Steps 4 and 5: Unit value changes and market size analyses .............................................. 216 Recreational bird and wildlife watching .................................................................................. 221 Recreational beach use ........................................................................................................... 224 Ecosystem sustainability ......................................................................................................... 225 Climate regulation .................................................................................................................... 229 Value of CO2 sequestration ...................................................................................................... 230 Results .................................................................................................................................230 Conclusions and recommendations....................................................................................234 8 NNBF Policy Challenges and Opportunities ............................................................................... 237 Introduction .......................................................................................................................... 237 Approach ............................................................................................................................... 237 Outcomes ..............................................................................................................................239 Theme 1: Science, engineering, and technology ................................................................... 239 ERDC SR-15-1 vi Theme 2: Communication and outreach ................................................................................ 241 Theme 3: Leadership and institutional coordination ............................................................. 242 Summary of opportunities for action .................................................................................. 245 9 The Path Forward ............................................................................................................................. 247 References ............................................................................................................................................... 249 Appendix A: NNBF Mapping of the NACCS Study Area .................................................................... 272 Appendix B: Examples of Construction Costs of Nature-Based Infrastructure Projects .......... 293 Appendix C: How to Determine Hydrodynamic and Meteorological Characteristics ................ 305 Appendix D: Supplemental Vulnerability Data and Information ..................................................... 314 Appendix E: Coastal Landscape Metrics ............................................................................................ 325 Appendix F: Vulnerability Metric Quantification Example ............................................................... 333 Appendix G: Features-Services Matrix ................................................................................................ 341 Appendix H: Ecosystem Goods and Services per Feature Tables .................................................. 347 Appendix I: Causal Maps ........................................................................................................................ 406 Appendix J: Service Quantification Protocols .................................................................................... 412 Report Documentation Page ERDC SR-15-1 vii Figures and Tables Figures Table 1. Examples of NNBF relevant to coastal systems (USACE 2013). ............................................... 4 Figure 1. NNBF evaluation implementation framework. ........................................................................ 12 Figure 2. Shepard (1973) coastal classification hierarchy for the NACCS study area. ....................... 16 Figure 3. Coastal classification for the NACCS study area. .................................................................... 18 Figure 4. Conceptual cross-shore profiles of the Drowned River Valley class for A. the valley mainstem and B. valley tributaries. Not pictured are natural or artificial islands. (A. inset image taken from NOAA National Marine Fisheries Service Habitat Conservation webpage http://www.habitat.noaa.gov/ restoration/techniques /livingshorelines.html; B. inset image taken from Google Earth Pro, February 2014.) ............................................................................ 20 Figure 5. Factors contributing to weathering and erosion of bluffs and low banks, exemplary of features found in Chesapeake and Delaware Bays. Some bluffs may be fronted with narrow sand beaches or shore protection. ......................................................................... 21 Figure 6. Conceptual cross-shore profile of the Drowned Glacial Erosion class (inset image from Save The Bay, Inc.). ............................................................................................................................. 22 Figure 7. Conceptual cross-shore profiles of the Glacial Depositional Coast class for A. exposed areas and B. sheltered areas (both A. and B. insets are screenshots from ArcMap). ................................ 24 Figure 8. Conceptual cross-shore profile of the Marine Deposition Barrier Coast class. Note the barrier feature can be a barrier island or a spit (inset is a screenshot from ArcMap). ................................ 25 Figure 9. Geomorphic features in barrier spits common in New England. Overwash represents transfer of sand from the open coast into the back bay/pond (figure from USGS). .................................... 26 Figure 10. Conceptual cross-shore profile of beach plain coast type (inset is a screenshot from ArcMap). .............................................................................................................................................. 27 Figure 11. Common sources and sinks of beach sediments (Bird 2008). .......................................... 29 Figure 12. Vulnerability and related concepts.......................................................................................... 52 Figure 13. Risk analysis process (Baker 2005). ...................................................................................... 54 Figure 14. Simple, coupled, human-environment system. ..................................................................... 64 Figure 15. Decision tree to support the community’s self-assessment of vulnerability and resilience. Elements in the tree can be customized to reflect the needs of each community’s unique situation. ................................................................................................................... 84 Figure 16. An example of NNBF performance was seen on the Rockaway Peninsula in Queens, NY (USA) after the storm. The pictures on the top compare a site with NNBF structures (i.e., dunes) offering a level of protection to the inland communities, whereas the picture on the bottom compares a site absent NNBF (Source: http://www.nyc.gov/html/sirr/html/report/report.shtml). ............................................................................... 95 Figure 17. The link between NNBF features and ecosystem goods, services and benefits production (adapted from van Oudenhoven et al. 2012) characterized by state conditions (structure and function under conditions driven by forces) attributed to natural, nature-based and structural features that generate benefits of perceived value that can be used to make decisions and inform policy. ........................................................................................................ 98 ERDC SR-15-1 viii Figure 18. The spiraled approach offered a unique opportunity for planners and managers to actively engage with stakeholders in the process through reflexive team meetings that promoted active learning, increasing knowledge and fostering trust and confidence in the products while honing the skills and competence of the team. .......................... 105 Figure 19. Performance metric development process. ........................................................................107 Figure 20. Example of a communication product generated through this exercise. In each successive panel (starting at the top and moving down), new features are deployed, and their corresponding benefits (generated by goods and services tied to functions/processes driven by ecosystem states tied to feature components) are checked off as they are produced. ..........................................................................................................................117 Figure 21. A generic illustration of the causal map construct used in this study. ............................ 121 Figure 22. Metric for storm surge protection by beaches based on height and width. ................... 134 Figure 23. Metric for beach recreation based on length, beach access, width, and population density. ................................................................................................................................... 136 Figure 24. Metric for biodiversity of shrub wetlands based on vegetation cover and proportion natives in the wetland, tree cover within 100 m of wetland, proximity to other open water and wetlands within 1 km, and ditch density in the wetland. ........................................ 137 Figure 25. Metric for provisioning by salt marshes based on vegetation cover and proportion natives in the salt marsh, impervious cover and agriculture within 100 m of the salt marsh, and ditch density in the salt marsh. ................................................................................... 138 Figure 26. Metric for forest biodiversity based on vegetation cover, proportion natives, and morphological spatial pattern analysis. ................................................................................................. 139 Figure 27. Conceptual diagram of the NNBF decision framework showing options for operating across tiers that represent a decision-making continuum. A study can be implemented at any level or repeated when more data is available to lower uncertainty. ............. 143 Figure 28. Graph of principle components analysis of the objective weights. The shaded regions of the graph show the alternatives (D1, D3, and J1) favored under the analysis (from Runge et al. 2011). ......................................................................................................................... 159 Figure 29. Continuum of advancing and retreating coasts (Bird 2008). .......................................... 174 Figure 30. SMSP flowchart. ..................................................................................................................... 175 Figure 31. NACCS feature types for Long Island Sound as determined by ESI. ................................177 Figure 32. A) Home screen of the technique library screening tool; B) Techniques Library Screening tool with parameters selected. ............................................................................................. 186 Figure 33. Example of technique-specific information included within the tool. ............................. 186 Figure 34. A structured evaluation framework collectively developed by stakeholder representatives involved in the Long Island Sound Dredged Materials Management Plan Working Group. Through group discussion and individual interviews, this approach fairly, transparently, and quantitatively incorporates stakeholder preferences and concerns to inform the decision process. .................................................................................................................... 190 Figure 35. Results of the Long Island Sound DMMP working-group interviews. Relative preferences among criteria were elicited in the context of three different material types. Group averages are shown in the colored bars, individual responses are shown via the diamond, square, and circular dots. (Note: results for the four main categories are shown here, but preferences were also elicited for sub-criteria within each of these categories)............. 191 Figure 36. Screenshot of the D2M2 model built using data prepared for the LIS DMMP. ............. 193 Figure 37. Map of the LIS region identifying regional dredging centers and projected dredging needs of a 30 yr time horizon. ................................................................................................ 194 ERDC SR-15-1 ix Figure 38. Evaluation tree of cost and effect criteria. .......................................................................... 197 Figure 39. Map of LIS route network connecting dredging and placement sites used in the D2M2 optimization model. ...................................................................................................................... 198 Figure 40. Relative results of Cost, Effect, and Mixed D2M2 weighting schemes. ......................... 199 Figure 41. Case study locations. ............................................................................................................. 205 Figure 42. Jamaica Bay site map from 2012. ....................................................................................... 206 Figure 43. Cape May site map from 2011. ............................................................................................ 207 Figure 44. South Cape Charles–Bay Creek before restoration (1994). The red box indicates the natural tiger beetle habitat north of the restoration site. ............................................ 208 Figure 45. Post project showing eight breakwaters at Cape Charles South. ................................. 209 Figure 46. Cape Charles South Beach width within the project area over time. Values represent the distance that shoreline edge has moved relative to the 1994 shoreline. Boxes show the 25th and 75th percentiles of beach movement for a given year. The bold horizontal line shows the median value. ................................................................................................ 216 Figure 47. Hurricane Sandy storm surge at Cape Charles South. ....................................................... 217 Figure 48. NACCS planning reaches (USACE 2015). ........................................................................... 273 Figure 49. NNBF within NACCS planning reaches NH1 and MA1. ...................................................... 274 Figure 50. NNBF within NACCS planning reaches MA2 and MA3. .................................................... 275 Figure 51. NNBF within NACCS planning reaches MA4 and MA5. ...................................................... 276 Figure 52. NNBF within NACCS planning reaches MA6 and RI1. ....................................................... 277 Figure 53. NNBF within NACCS planning reaches RI2 and NY1. ....................................................... 278 Figure 54. NNBF within NACCS planning reaches NY2 and NY3. ...................................................... 279 Figure 55. NNBF within NACCS planning reaches NY4 and NY5. ...................................................... 280 Figure 56. NNBF within NACCS planning reaches NY_NJ1 and NJ1. ................................................ 281 Figure 57. NNBF within NACCS planning reaches NJ2 and NJ3. ........................................................ 282 Figure 58. NNBF within NACCS planning reaches NJ4 and NJ5. ....................................................... 283 Figure 59. NNBF within NACCS planning reaches DE1 and PA1. ...................................................... 284 Figure 60. NNBF within NACCS planning reaches DE2 and DE3. ...................................................... 285 Figure 61. NNBF within NACCS planning reaches MD1 and MD2. .................................................... 286 Figure 62. NNBF within NACCS planning reaches MD3 and MD4. ................................................... 287 Figure 63. NNBF within NACCS planning reaches MD5 and DC1. .................................................... 288 Figure 64. NNBF within NACCS planning reaches VA1 and VA2. ....................................................... 289 Figure 65. NNBF within NACCS planning reaches VA3 and VA4. ....................................................... 290 Figure 66. NNBF within NACCS planning reaches VA5 and VA6. ....................................................... 291 Figure 67. NNBF within NACCS planning reach CT1. ........................................................................... 292 Figure 68. Example of NDBC wave and atmospheric measurement locations. .............................. 306 Figure 69. Example of WIS station locations. ........................................................................................ 306 Figure 70. Example of WIS extremal analysis for Station 63125. ...................................................... 307 Figure 71. Fetch estimate diagram. ........................................................................................................ 309 Figure 72. Storm surge at the Battery, NY, during Hurricane Sandy (2012). .................................... 310 Figure 73. Example functional relationship to value vulnerability (Bosom and Jimenez 2011). ........................................................................................................................................................ 323 ERDC SR-15-1 x Figure 74. Drowned river valley coast schematic. ................................................................................. 325 Figure 75. Drowned glacial erosional coast schematic. ...................................................................... 327 Figure 76. Glacial depositional coast with bluff schematic. ................................................................ 329 Figure 77. Glacial depositional coast schematic. ................................................................................. 331 Figure 78. Spatial map of (A) beach slope, (B) beach width, and (C) barrier island width metrics. ...................................................................................................................................................... 338 Figure 79. Spatial map of (A) short-term shoreline change rate, (B) long-term shoreline change rate, and (C) dune elevation metrics. ....................................................................................... 339 Figure 80. Spatial map of (A) dune volume, (B) distance from sound to dune, and (C) wave runup metrics. ........................................................................................................................................... 340 Figure 81. Causal map for structural features alone. .......................................................................... 407 Figure 82. Causal map for NNBF and the pathways to providing reduced storm-surge related flooding damages benefits. ........................................................................................................ 408 Figure 83. Causal map for NNBF and the pathways to providing habitat for TES species. ............ 409 Tables Table 1. Examples of NNBF relevant to coastal systems (USACE 2013). ............................................... 4 Table 2. Examples of nonstructural and structural features relevant to coastal systems (USACE 2013). ............................................................................................................................................... 5 Table 3. Primary drivers of geomorphic features. .................................................................................... 38 Table 4. Primary drivers of features within each coast type................................................................... 39 Table 5. Wentworth grain size classification for sediments. .................................................................. 43 Table 6. Web links to all State plant databases within the study area. ................................................ 45 Table 7. Definitions of resilience used by various organizations in recent studies; the key words (or synonyms) are prepare, resist, recover, and adapt. ............................................................... 56 Table 8. Relative risk metrics assigned by Gornitz (Gornitz and Kanciruk 1989; Gornitz et al. 1991; Gornitz and White 1992) for a Coastal Vulnerability Index (CVI)........................................... 59 Table 9. Example situation vulnerability profile. ....................................................................................... 65 Table 10. Vulnerability factor and system function matrix. ..................................................................... 68 Table 11. Vulnerability metrics developed for the beach and dune system. ....................................... 70 Table 12. Vulnerability metrics for marine depositional barrier coast landscape. .............................. 72 Table 13. Vulnerability metrics for selected nature-based features. ..................................................... 74 Table 14. Step 2 – Identify the benchmark and future storm conditions. ........................................... 85 Table 15. Step 3 – Identify the critical infrastructure, facilities, and recovery goals for the benchmark (RG-B) and future (RG-F) storms. .......................................................................................... 87 Table 16. Step 4 – Identify critical transportation routes, issues, and recovery goals for the benchmark (RG-B) and future (RG-F) storms. .......................................................................................... 89 Table 17. Step 5 – Identify the critical protective features (NNBF, structural, and blended measures) and the recovery goals for the benchmark (RG-B) and future (RG-F) storms. ................. 90 Table 18. Step 6 – Overall community resilience rating. ........................................................................ 91 Table 19. Selected ecosystem goods and services typologies (sorted by publication date). ............ 99 Table 20. Risk reduction features considered in this study. ............................................................... 109 ERDC SR-15-1 xi Table 22. Feature decomposition - NNBF example using the beach feature to demonstrate the process. Note that only 4 of the 14 structural components and associated processes, ecosystem services, benefits, and metrics associated with beaches are shown here. Refer to Appendix H (Table 79) for the entire suite of ecosystem goods and services associated with this feature. ................................................................................. 115 Table 23. Statistical results of the November 2013 expert elicitation exercise. .............................. 120 Table 24. Hypothetical example of a BPJ voting matrix. Stakeholders and/or decision makers provide their perceived benefits in the body of the table on the basis of benefits (e.g., B1, B2, B3) tied to ecosystem goods and services given a particular design option (e.g., Plan A, Plan B, Plan C) and offer their perceived values in terms of which benefits are the most important to them (top row shown in dark green indicating highest scores). The columns on the right relatively value the outcomes based on the weights and benefits recorded. ................................................................................................................................................... 120 Table 25. Ecosystem goods and service values based on peer-reviewed original research in temperate North America/Europe [2012 $/(acres*yr)].................................................................. 122 Table 26. Ecosystem goods and service values based on peer-reviewed original research, grey literature, and meta-analysis studies in temperate North America/Europe [2012 $/(acres*yr)]. ............................................................................................................................................ 123 Table 27. Geographic information system (GIS) data used to develop metrics for ecosystem services. ................................................................................................................................. 125 Table 28. Data layers derived from sources in Table 27. ..................................................................... 128 Table 29. GIS operations for identifying and/or extracting NNBF. ...................................................... 131 Table 30. Major storms and associated storm surge elevation in the North Atlantic in the past 100 yr (from Needham and Keim 2012; http://surge.srcc.lsu.edu/data.html)...................... 135 Table 31. NPP estimates for ecosystems in the NACCS study area. .................................................. 139 Table 32. Basic construct of the framework showing objectives, metrics and alternatives for NNBF. Table populated by proxy information and is designed to be sufficiently flexible as to be used in all three tiers of the framework. ................................................................................. 144 Table 33. Stakeholder preference survey matrix. The objectives and metrics are carried over from Table 32, with preferences for objectives and consequent weighting of objectives. ................................................................................................................................................. 145 Table 34. Example construct for Tier 1 of the framework. The objectives and metrics are carried over from Table 32 and Table 33. .............................................................................................. 146 Table 35. Example construct for Tier 3 of the framework. The objectives and metrics are carried over from Table 32 to Table 34. ..................................................................................................147 Table 36. Example Tier 1 stakeholder preference survey (SH = Stakeholder). ................................ 148 Table 37. Tier 1 framework matrix populated by information obtained from SME (Part I). ............. 150 Table 38. Tier 1 framework matrix populated by information obtained from SME (Part II). ........... 153 Table 39. Tier 2 framework matrix informed by numerical models and/or data from existing similar projects in the region. .................................................................................................... 155 Table 40. Composite scores from trade-offs for each alternative, using weights of participating stakeholders. Green shading indicates the highest ranking alternative for each stakeholder group, representing the top two ranked alternatives (D1 and D3) (from Runge et al. 2011). .................................................................................................................................. 158 Table 41. Consequence table for the Tier 1 evaluation using a hypothetical simple semiquantitative scale to inform the storm protection metric where the matrix was populated by information obtained from SME. ..................................................................................... 160 ERDC SR-15-1 xii Table 42. Consequence table for the Tier 2 evaluation using a hypothetical quantitative measure to inform the storm protection metric from regional data................................................... 162 Table 43. Consequence table for the Tier 3 evaluation using a numerical model to assess storm surge and wave height under several alternatives including NNBF. Results of the modeled water level and wave height for a standard storm are presented along with a value for average annual damages avoided based on a suite of storms. ......................................... 163 Table 44. Cross-walk between ESI and NACCS. ..................................................................................... 176 Table 45. Projects in RI, CT, and NY with multiple dredging events (1990–2013) .......................... 182 Table 46. Effect input field criteria and subcriteria for impacts to the community. ......................... 196 Table 47. Ecosystem goods and services analyzed and metrics intended for use in the analysis. ..................................................................................................................................................... 212 Table 48. Results for Jamaica Bay. ........................................................................................................ 231 Table 49. Results for Cape May Meadows. .......................................................................................... 232 Table 50. Results for Cape Charles South. ........................................................................................... 233 Table 51. GIS source layers and geoprocessing descriptions used to develop the study’s NNBF mapping products. ........................................................................................................................ 272 Table 52. USACE shoreline protection costs converted to 2002 dollar ($) value (after USACE 2003). ........................................................................................................................................... 293 Table 53. Shore protection projects costs converted to 2013 price levels (USACE, 2013). ........... 297 Table 54. Cost of substrates for use in oyster bed development (USACE 2012a). .......................... 298 Table 55. Habitat restoration costs (Grabowski et al. 2012). ............................................................. 298 Table 56. Vegetation cover costs (after Devore 2013). ....................................................................... 299 Table 57. Soft or nonstructural stabilization (after Devore 2013). ..................................................... 299 Table 58. Structures for living shorelines, bulkheads, seawalls, and revetments (after Devore 2013). ........................................................................................................................................... 300 Table 59. Nearshore breakwaters (after Devore 2013). ..................................................................... 300 Table 60. Engineers cost estimate for White Island restoration. ........................................................ 301 Table 61. Approximate costs of riverbank stabilization technique (Allen et al. 2006)..................... 302 Table 62. Shoreline restoration projects information and costs (adapted from Allen et al. 2006). ................................................................................................................................................................. 304 Table 63. Thieler and Hammer-Klose (1999) ranking of coastal vulnerability for the U.S. Atlantic Coast. ..................................................................................................................................................... 314 Table 64. Thieler and Hammer-Klose (2000a) ranking of coastal vulnerability for the U.S. Pacific Coast. ....................................................................................................................................................... 315 Table 65. Thieler and Hammer-Klose (2000b) ranking of coastal vulnerability for the U.S. Gulf Coast. ................................................................................................................................................................... 315 Table 66. Social variable descriptions used in social vulnerability index of Boruff et al. (2005). ............ 316 Table 67. Factors that explain majority of vulnerability variance for U.S. coastal counties (Boruff et al. 2005). ......................................................................................................................................................... 317 Table 68. Vulnerability rankings for national/regional scale from McLaughlin and Cooper (2010). .................................................................................................................................................................318 Table 69. Vulnerability rankings for local scale from McLaughlin and Cooper (2010). ................... 320 Table 70. Vulnerability rankings from Abuodha and Woodroffe (2006). ........................................... 321 Table 71. Metrics for drowned river valley coastal landscape. ............................................................ 325 ERDC SR-15-1 xiii Table 72. Metrics for drowned glacial erosional coastal landscape. ................................................. 327 Table 73. Metrics for glacial depositional coastal landscape with bluffs. ......................................... 329 Table 74. Metrics for glacial depositional coastal landscape without bluffs. ................................... 331 Table 75. Metrics values for the Marine Depositional Barrier Coast example. ................................ 333 Table 76. Feature-Services matrix for NNBF produced by the PDT for the study based on literature and expert opinion. Goods and services highlighted in blue indicate primary concerns of the NACCS recovery efforts. ............................................................................................... 343 Table 77. Feature-Services matrix for NNBF and structural feature complexes produced by the PDT for the study based on literature and expert opinion. Goods and services highlighted in blue indicate primary concerns of the NACCS recovery efforts. ................................ 345 Table 78. Feature-Services matrix for structural features produced by the PDT for the study based on literature and expert opinion. Goods and services highlighted in blue indicate primary concerns of the NACCS recovery efforts. .................................................................. 346 Table 79. NNBF: Beach (sand, gravel, cobble). ..................................................................................... 348 Table 80. NNBF: Mudflat / Sandflat or Tidalflat. .................................................................................. 350 Table 81. NNBF: Bluff or Scarp (any material, if sand assume eroding dune). ................................ 352 Table 82. NNBF: Dune / Swale Complex. .............................................................................................. 353 Table 83. NNBF: Salt Marsh (emergent herbaceous). ......................................................................... 356 Table 84. NNBF: Shrub-scrub Wetlands (brackish). ............................................................................. 359 Table 85. NNBF: Flooded Swamp Forest (brackish). ............................................................................ 362 Table 86. NNBF: Maritime Grassland. .................................................................................................... 365 Table 87. NNBF: Maritime Shrubland. .................................................................................................... 367 Table 88. NNBF: Maritime Forest. ........................................................................................................... 370 Table 89. NNBF: Submerged Aquatic Vegetation or Aquatic vegetation Bed (seagrass, other - fresh or saline). .............................................................................................................................. 372 Table 90. NNBF: Riparian Buffer. ............................................................................................................. 374 Table 91. NNBF: Emergent Herbaceous Marsh / Wetland (fresh). .................................................... 377 Table 92. NNBF: Shrub-scrub Wetland (fresh). ..................................................................................... 379 Table 93. NNBF: Flooded Swamp Forest (fresh). .................................................................................. 382 Table 94. NNBF: Pond. ............................................................................................................................. 384 Table 95. NNBF: Terrestrial Grassland. .................................................................................................. 386 Table 96. NNBF: Terrestrial Shrubland. .................................................................................................. 388 Table 97. NNBF: Terrestrial Forest. .......................................................................................................... 391 Table 98. NNBF and structural feature complexes: Reef or Mollusk reef, Intertidal or Submerged (also see Breakwater). ........................................................................................................ 393 Table 99. NNBF and structural feature complexes: Living Shoreline (e.g., vegetation w/ sills, benches, breakwaters). ................................................................................................................... 395 Table 100. Structural features: Levee. ................................................................................................... 397 Table 101. Structural features: Storm Surge Barrier. ........................................................................... 399 Table 102. Structural features: Seawall / Revetment / Bulkhead. .................................................... 401 Table 103. Structural features: Groin. .................................................................................................... 402 Table 104. Structural features: Breakwater........................................................................................... 404 ERDC SR-15-1 xiv Table 105. GIS operations for deriving metrics for Aesthetics/Cultural Heritage. GIS data layers for features were generated using procedures from Table 29. For the GIS operations, the tool is listed and input data layers are listed in parentheses. NNBF are listed in the GIS operation either generically as "FEAT" (i.e., feature) or specifically named. GIS operation input parameters are identified with p. ......................................................................... 420 ERDC SR-15-1 xv Preface This report offers details regarding the use of natural and nature-based features to improve coastal resilience and was designed to support efforts under the North Atlantic Coast Comprehensive Study (NACCS) (USACE 2015). The report was prepared jointly by staff from the U.S. Army Engineer and Research Development Center (CEERD) and the Institute of Water Resources (CEIWR) at the request of the U.S. Army Corps of Engineers, National Planning Center for Coastal Storm Risk Management. Contributors to the report include the following: Project Delivery Team: Todd Bridges (CEERD), Paul Wagner (CEIWR), Kelly Burks-Copes (CEERD), Craig Fischenich (CEERD), Deborah Shafer (CEERD), Ty Wamsley (CEERD), Burton Suedel (CEERD), Edmond Russo (CEERD), Joseph Gailani (CEERD), Emily Vuxton (CEIWR), and Lauren Leuck (CEIWR). Contributing Team: Todd Bridges (CEERD), Paul Wagner (CEIWR), Kelly Burks-Copes (CEERD), Craig Fischenich (CEERD), Deborah Shafer (CEERD), Ty Wamsley (CEERD), Burton Suedel (CEERD), Edmond Russo (CEERD), Joseph Gailani (CEERD), Pam Bailey (CEERD), Candice Piercy (CEERD), Cheryl Pollock (CEERD), Jane Smith (CEERD), Ashley Frey (CEERD), Andrew Morang (CEERD), Zachary Collier (CEERD), Katherine Brodie (CEERD), Lauren Dunkin (CEERD), Patrick O’Brien (CEERD), David Raff (CEIWR), Julie Rosati (CEERD), Sarah Miller (CEERD), Jae Chung (CEIWR) Michael Deegan (CEIWR), Mark Gravens (CEERD), Bruce Pruitt (CEERD), Jeff Melby (CEERD), Jennifer Wozencraft (CEERD), Michelle Haynes (CEIWR), Matthew Bates (CEERD), Robert Thomas (CEERD), Linda Lillycrop (CEERD), Lisa Wainger (University of MD), Sam Sifleet (University of MD), Scott Bourne (CEERD), Emily Vuxton (CEIWR), and Lauren Leuck (CEIWR). Citation: Bridges, T. S., Wagner, P. W., Burks-Copes, K. A., Bates, M. E., Collier, Z., Fischenich, C. J., Gailani, J. Z., Leuck, L. D., Piercy, C. D., Rosati, J. D., Russo, E. J., Shafer, D. J., Suedel, B. C., Vuxton, E. A., and Wamsley, T. V. 2014. Use of natural and nature-based features (NNBF) for coastal resilience. ERDC SR-15-1. Vicksburg, MS: U.S. Army Engineer Research and Development Center. ERDC SR-15-1 xvi Executive Summary Natural, nature-based, nonstructural, and structural are terms used to describe the full array of measures that can be employed to support coastal resilience and risk reduction (U.S. Army Corps of Engineers (USACE) 2013). By definition, natural features are created and evolve over time through the actions of physical, biological, geologic, and chemical processes operating in nature. Natural coastal features take a variety of forms, including reefs (e.g., coral and oyster), barrier islands, dunes, beaches, wetlands, and maritime forests. The relationships and interactions among the natural and built features comprising the coastal system are important variables determining coastal vulnerability, reliability, risk, and resilience. Conversely, nature-based features are those that may mimic characteristics of natural features, but are created by human design, engineering, and construction to provide specific services such as coastal risk reduction. The built components of the system include nature-based and other structures that support a range of objectives, including erosion control and storm risk reduction (e.g., seawalls, levees), as well as infrastructure providing economic and social functions (e.g., navigation channels, ports, harbors, residential housing). An integrated approach to coastal resilience and risk reduction will employ the full array of measures, in combination, to support coastal systems and communities. In order to pursue an integrated approach to coastal resilience, the North Atlantic Coast Comprehensive Study (NACCS) formed a team to develop a framework for identifying and evaluating opportunities for integrating natural and nature-based features (NNBF) (USACE 2015). NNBF can be used to enhance the resilience of coastal areas threatened by sea level rise and coastal storms. For example, beaches are natural features that can provide coastal storm risk reduction and resilience where their sloping nearshore bottom causes waves to break—dissipating wave energy over the surf zone. Dunes that back a beach can act as physical barriers that reduce inundation and wave attack to the coast landward of the dune. Coastal wetlands can attenuate waves and stabilize sediments, thereby providing coastal storm protection. Nature-based features are acted upon by processes operating in nature, and as a result, generally must be maintained by human intervention to ERDC SR-15-1 xvii provide the functions and services for which they were built. Coastal systems are naturally dynamic, and NNBF respond in many ways to storms—with some responses being temporary and others permanent. Storm effects on wetlands often include erosion, stripped vegetation, and salinity burn—all of which can decrease long-term productivity. Storms, however, also introduce mineral sediments that contribute to long-term sustainability with respect to sea level rise. In addition to providing engineering functions related to reducing risks from coastal storms, NNBF can provide a range of additional ecosystem services, including those supporting coastal ecosystems and communities. A true systems approach to coastal risk reduction and resilience requires consideration of the full range of functions, services, and benefits produced by coastal projects and NNBF. These include benefits related to commercial and recreational fisheries, tourism, provisioning of clean water, habitat for threatened, endangered, and sensitive species (TES), and support for cultural practices. Developing a more complete understanding of the ecosystem goods and services provided by the full range of coastal features, individually and in combination, will help to inform plan formulation and benefit determination for risk reduction strategies. Knowledge about the performance of natural, nature-based, nonstructural, and structural features varies, as do the methods to calculate and measure performance. The dynamic behavior and response of NNBF to threats such as coastal storms and development can affect their performance with respect to system-level risk reduction and resiliency objectives. Moreover, it is important to design nature-based features in such a way that they will establish and/or re-establish natural processes and become as self-sustaining as possible. Federal investment in the use of NNBF intended to provide ecosystem goods and services, including coastal risk reduction and resiliency, should be based upon solid scientific and engineering evidence about the function and performance of these features. As with structural measures, some nature-based features will require routine maintenance and these costs should be factored into analyses. Purpose of this study The purpose of this study was to fill knowledge gaps and produce relevant information to support the identification, evaluation and integration of NNBF with structural and non-nonstructural measures in order to support coastal risk reduction and resilience. Developing a comprehensive ERDC SR-15-1 xviii framework was viewed as an important next step in coordinating the advancement of NNBF among the many organizations and stakeholders engaged in the management of coastal systems. The framework includes a range of activities relevant to the use of NBF and is divided into three categories of activities: Organizational Alignment, Evaluation and Implementation. Steps in the framework are enumerated here and briefly described below: 1. Classifying, mapping, and characterizing NNBF 2. Developing vulnerability metrics 3. Developing performance metrics 4. Assessing and ranking proposed alternatives 5. Considering sediment as a resource for NNBF 6. Monitoring and assessing NNBF to support adaptive management 7. Considering policy challenges and implications. Classification, mapping, and feature characterization A classification system was developed for NNBF that applies two existing systems that are widely used both nationally and internationally. The first is a geomorphologic classification system of coastline types based on Shepard (1973), and illustrated in the Coastal Engineering Manual (USACE 2002). For each of the geomorphologic classes present within the study area, one or more profiles were generated to illustrate the typical arrangement of geomorphic features, including those potentially identified as NNBF. The profiles can be used to illustrate the types of NNBF that could be expected to occur or be used in the landscape, as well as how combinations of multiple features could be applied to increase the level of coastal protection afforded. Geomorphic features typical of each coast type are described in detail. Many features are coincident and/or provide similar functions in the landscape and are described together. The driving processes that describe each feature are identified; information on processes is detailed separately to avoid repetition. These processes (e.g., wave attack, erosion, sediment transport, changes in sea level, glaciation) also continue to act on and shape NNBF in the coastal environment. Understanding these processes will be important to engineers and scientists involved in the design and construction of NNBF. Morphological and physical attributes of each feature type are tabulated for each coast type. The approach applied to NNBF is the U.S. National Vegetation Classification (USNVC) (Grossman 1998). This system delivers a ERDC SR-15-1 xix comprehensive single-factor approach to hierarchical classification of ecological communities based on vegetation. A major advantage of this system is that geospatial mapping layers are available for the study area, and detailed descriptions of the plant communities are available for each State through the State Natural Heritage programs. The detailed descriptions of the plant community associations can be used in a variety of ways. For example, knowledge of the species composition and structural characteristics of the vegetation can be used to estimate the degree of surface roughness and impedance to the flow of water during storm events. The descriptions of the species associations can also be used as a planting guide to select the most appropriate suite of plant species for the NNBF under consideration. Mapping layers of the vegetation classes can also be used to identify NNBF characteristics in relation to conservation and preservation goals. Approach for developing coastal vulnerability metrics Coastal areas of the U.S. are threatened by erosion and damage due to storm waves, wind, and surge. Evaluation of the role of NNBF, in the context of coastal zone management and storm damage risk reduction, requires the assessment of vulnerability in natural and human environments. Vulnerability is conceptualized in many different ways and depends on the scientific background of those assessing vulnerability. Here is defined an approach to assessing vulnerabilities in order to identify beneficial applications of NNBF. A comparison was made of previous approaches to assessing vulnerability, which demonstrated the subjective nature of developing vulnerability metrics. The various approaches differ in how vulnerability is measured as they depend on the purpose of the vulnerability assessment, the spatial and temporal scale for which the assessment is being conducted, the specific coastal characteristics for the area of interest, and data availability. Metrics can be both quantitative and qualitative. While qualitative metrics are non-numerical, they may still reflect measurable characteristics such as the relative resistance of a given landform to erosion. Comprehensive approaches recognize that overall vulnerability is determined by physical coastal characteristics (e.g., geology, elevation), coastal forcing (e.g., tide range, wave height, storm frequency), and socioeconomic characteristics (e.g., population, cultural heritage, land use). Finally, it is also recognized that assessment of vulnerability can be improved through process parameterization or modeling. ERDC SR-15-1 xx Vulnerability is a function of the hazard to which a system is exposed, the sensitivity of the system to the hazard, and the system’s adaptive capacity. A satisfactory conceptual approach for identifying and defining meaningful metrics must consider all three of these components to be complete. The approach that was developed was designed to ensure a set of metrics is developed for a complete assessment of vulnerability for a wide range of systems and hazards at multiple scales, with specific emphasis on NNBF. Metrics for application in assessing vulnerability for multiple coastal landscapes are developed. The vulnerability of anything on the landscape is directly linked to natural coastal landscape and NNBF vulnerability. The metrics developed are specifically intended for assessing relative vulnerability of coastal landscapes along the northern Atlantic coast, understanding how NNBF influence vulnerability of a coastal landscape, and understanding vulnerability of specific NNBF. The metrics presented are not all of equal importance, nor are they mutually exclusive. The actual selection of metrics to apply for a given vulnerability assessment will depend on many factors, most notably the purpose and scale of the vulnerability assessment and data availability. Performance metrics for ecosystem goods and services generated by NNBF Identifying appropriate and effective applications of NNBF will be guided by the benefits and services these features can provide. A comprehensive set of relevant performance metrics for NNBF was developed, expressed in terms of ecosystem goods and services, that can be used to characterize (either qualitatively or quantitatively) the benefits generated by these features. Twenty-one ecosystem-based goods and services were developed along with 72 quantitative performance metrics that capture a full suite of social, environmental, and economic benefits generated by 30 NNBF and structural features, implemented individually and in combination, to promote flood risk reduction and improve ecosystem resilience. A general methodology was developed to qualitatively analyze these services for NNBF applications. Each NNBF (e.g., dune-swale complex) was decomposed into its critical components (i.e., physical characteristics such as soils and vegetative properties), and the ecosystem functions and processes associated with these components were linked through causal pathways to the goods or ERDC SR-15-1 xxi services the feature would provide (e.g., aesthetics, habitat provisioning, wave-attack reduction). From there, benefits were derived (e.g., scenic beauty, TES protection, flood risk reduction) and a metric for each line of evidence was developed (e.g., vegetative cover visible to local community, habitat suitability indices, and flood-prone-area reduction). Three methodologies were developed to analyze ecosystem goods and services for NNBF applications. A matrix was developed aligning NNBF with the various services they provide, and a qualitative ranking system was produced to elicit stakeholder preferences with regards to NNBF applications. A second, semi-quantitative method was developed to expose lines of evidence linking features to benefits through causal pathways. This approach can be operationalized in the future using scientific evidence and quantifications to measure recovery plan performance with respect to NNBF inputs. The third approach focused on the development of quantifiable metrics using readily available geographic information system (GIS)-based data to characterize landscape-level performance of NNBF using a variety of geoprocessing techniques documented in the relevant scientific literature. In addition, a Benefit Transfer Table was developed using literature-based values in order to provide an alternative means for characterizing the goods and services in a quantitative fashion. Framework for assessing and ranking NNBF alternatives A flexible, tiered evaluation framework was developed for analyzing the contribution of NNBF to system resilience, while accounting for other services generated by NNBF. The framework uses a structured decision-making process, performance metrics, and available data to guide the identification of appropriate applications of NNBF. The tiers of analysis, beginning with evaluation based on expert elicitation, will progress through stages employing greater levels of quantitative and engineering analysis. Each successive tier is more quantitative (to resolve uncertainties) and can build on previous tiers. The framework is compatible with alternative screening, prioritization, and benefit and cost analyses, depending on the tier. The framework includes how to use stakeholder preferences, how consequence tables can be derived consistently across the tiers, and the inherent characteristics that make the framework suitably appropriate and flexible. The evaluation framework includes processes for engaging stakeholder preferences regarding objectives in order to explore trade-offs among alternative configurations and uses of NNBF. The framework can be used to assess NNBF in a categorical fashion, as specific projects, or as ERDC SR-15-1 xxii groups of projects reflecting a particular alternative. NNBF alternatives, alone or in combination with structural features, are evaluated against an explicit set of the performance metrics. Performance may be determined using the expert opinion (in the first tier of analysis) or through application of detailed modeling and technical analyses (in subsequent tiers of analysis), or through a combination of inputs. Thus, the framework can be implemented, initially, with limited information and can be progressively applied through stages employing greater levels of quantitative and engineering analysis. A narrative describing how the approach applies, how to use stakeholder preferences and how the consequence tables can be derived at each of three tiers, and the inherent characteristics that make the framework suitably appropriate and flexible is presented using several examples. Regional sediment management (RSM) to support NNBF A life-cycle RSM strategy for placing dredged sediments beneficially in the study area was developed to support and sustain the use and value of NNBF. The intent was to have a means for comprehensively developing dredging and placement options in a technically appropriate and consistent manner in the context of stakeholder objectives. Relevant information and input was gathered from subject matter experts (SME) in the field of dredging and sediment management. A case-study application was developed using data and information from Long Island Sound (LIS). Beneficial use of dredged material has been a long-established practice within the study region. In the context of this practice, the developed strategy defines and distinguishes practices related to strategic placement of sediment, natural systems approaches, and Engineering with Nature (EWN). The results of a detailed literature review served as the basis for identifying and inventorying past best practices, underpinning technical information, and using evaluation tools to support the development of a Screening Methodology for Strategic Placement (SMSP). Field site visits to the region were used to gain firsthand information about current practices and to engage SME on dredging operational practices. The initial phase of the SMSP methodology concerns the identification of NNBF opportunities, which includes • identification of coastal geomorphic landscape features • condition assessment of features ERDC SR-15-1 xxiii • assessment of the benefit of dredged sediment applicability • identification of dredging/placement techniques compatible with the settings. Next, navigation channel Operations and Maintenance (O&M) sediment sources were estimated. This involved forecasting shoaling and dredging requirements, assessing the properties of materials to be dredged, and identifying dredging/placement techniques compatible with dredged sediments. With the foregoing information sets prepared, technically defensible options were inventoried for sediment source matching with beneficial use placement opportunities. A dredging/placement technique library was created and was related to forecasts of dredging/sediment placement activities in order to identify compatibilities. A case-study application of the SMSP was developed for Long Island Sound (LIS) in order to produce an example of strategic placement designs and costs for sediments that are forecasted to be dredged. In a separate effort, stakeholders engaged through the New England District of USACE had collaborated to define a set of problems, needs, and opportunities for dredged-material management in the region. Through this engagement, performance objectives, constraints, driving scenarios, and potential dredged-sediment management measures were summarized to inform the demonstration. Optimization of dredged-sediment management options with respect to life-cycle performance and cost was analyzed using an existing USACE modeling tool (D2M21). Using existing data and following the themes of the prior stakeholder preference elicitation, this tool was used to perform a trade-off analysis. The LIS case-study application of the SMSP was developed to provide a template for scoping comprehensive analyses that could be performed over the entire study area. Key elements along the path to wider application of the SMPS include • bench-scale testing the methodology for engaging stakeholders to identify dredged-sediment sources and placement options at multiple locations in the Study Area • critically reviewing bench-scale testing of the engagement methodology • refining the method based on critical review 1 http://el.erdc.usace.army.mil/dots/models.html ERDC SR-15-1 xxiv • applying refined method for the entire NACCS study area. Ecosystem service benefits of existing NNBF–A Hurricane Sandy case study An evaluation of ecosystem goods and services (EGS) produced by three coastal ecosystem restoration sites (Jamaica Bay, NY; Cape May Meadows, NJ; and Cape Charles, VA) within the study area was performed. The sites were distributed to provide geographic coverage of the study area; the sites also differed in terms of their objectives and construction details. To examine performance during extreme events, when some benefits of coastal ecosystem restoration would be expected to be at their peak, outcomes in restored and un-restored areas during Hurricane Sandy were compared. For all analyses, available data was used, including data that had been collected to document Hurricane Sandy impacts. The results of the evaluation indicate that the benefits provided by these projects were moderate to substantial in nature, particularly in terms of beneficial effects on rare species habitats and property value enhancements. The results of the evaluations indicate that with relatively cost-effective analysis methods, the changes in ecosystem goods and services as a result of ecological restoration projects can be quantified in terms that are meaningful to the public. Further, some of those changes could be translated into social values using damage costs avoided and benefit-transfer methods. The case-study evaluations allowed the identification of opportunities for improving and strengthening monitoring and performance evaluation of NNBF. Institutional barriers and opportunities related to NNBF Advancing practice related to NNBF will involve making changes to institutional practices across Federal, State, and local government levels, as well as other organizations. In order to inform the efforts of the NACCS, a workshop was conducted with the purpose of assessing the policy challenges that exist that may impair the implementation and use of NNBF to create coastal resilience and reduce coastal risk. Specifically, the identification of the policy challenges that exist within and among Federal agencies that have a role in the implementation of these features was sought. Thirty-four individuals from the Bureau of Ocean Energy Management, CDM Smith, the Department of Homeland Security (DHS), the USACE, the U.S. Environmental Protection Agency (USEPA), the U.S. Fish and Wildlife Service (USFWS), the U.S. Forest Service (USFS), the U.S. Geological Survey (USGS), HR Wallingford, the National Park Service (NPS), the ERDC SR-15-1 xxv National Ocean and Atmospheric Administration (NOAA), the National Wildlife Federation (NWF), and the Water Institute of the Gulf participated in the workshop. Several opportunities for addressing the challenges were identified and categorized as follows: • Science, Engineering, and Technology o Create NNBF demonstration projects to learn the best practices and uses of NNBF. o Generate a compilation of information on the ecosystem goods and services provided by NNBF. o Develop risk and resiliency performance metrics for NNBF. o Initiate a wiki-type repository of knowledge adjacent to a data portal that could include contact information of people involved in NNBF efforts in different organizations and agencies. • Leadership and Institutional Coordination o Improve regional coordination through existing mechanisms such as Silver Jackets, NOAA’s Sea Grant, and U.S. Department of Agriculture (USDA) extension offices. o Utilize public/private partnerships to implement NNBF. o Initiate the development of guidance and policies to achieve robust coordination and data sharing among resource and planning agencies. o Incorporate NNBF into existing decision support and communication tools. o Leverage partnerships and funding to promote NNBF in support of community resilience. o Develop a guidebook with information on NNBF that could be implemented during the recovery process following a disaster. • Communication and Outreach o Develop a policy digest with relevant definitions of NNBF, as well as the authorities, roles, and responsibilities of Federal, State, and local agencies that have jurisdiction or interest in the implementation of NNBF. o Form an NNBF community-of-practice. ERDC SR-15-1 xxvi Looking forward U.S. coastlines provide social, economic, and ecological benefits to the nation, but are especially vulnerable to risks from the combination of changing climate and geological processes and continued urbanization and economic investment. NNBF can help reduce coastal risks as a part of an integrated approach that draws together the full array of coastal features that contribute to enhancing coastal resilience. By employing sound science and engineering practices, collaborating organizations will be able to identify timely opportunities, formulate and evaluate robust alternatives, and implement feasible approaches for making use of NNBF to enhance the resilience of social, economic, and ecological systems in coastal environments. ERDC SR-15-1 xxvii Unit Conversion Factors Multiply By To Obtain acres 4,046.873 square meters cubic yards 0.7645549 cubic meters feet 0.3048 meters hectares 1.0 E+04 square meters horsepower (550 foot-pounds force per second) 745.6999 watts inches 0.0254 meters miles (U.S. statute) 1,609.347 meters miles per hour 0.44704 meters per second square miles 2.589998 E+06 square meters ERDC SR-15-1 xxviii Acronyms ADCIRC ADvanced CIRCulation Model ASCE American Society of Civil Engineers AZGF Arizona Game and Fish Department BoR Bureau of Reclammation BUDM Beneficial Use of Dredged Materials CAP NOAA’s Coastal Change Analysis Program CARRI Community and Regional Resilience Institute CDM Commander CELCP Coastal and Estuarine Land Conservation Program CERB Coastal Engineering Research Board CF Critical Facilities CI Critical Infrastructure CO-OPs NOAA’s Center for Operational and Oceanographic Products and Services CPI Consumer Price Index CRM Community Resilience Metric CRS Community Rating System Program CRSB Conceptual Regional Sediment Budget CSTORM-MS Coastal Storm Modeling System CVI Coastal Vulnerability Index CWCCIS Civil Works Construction Cost Index System D2M2 Dredged material Management Decisions Model DHS U.S. Department of Homeland Security DIS Dredging Information System DMMP Dredged Materials Management Plan DOER Dredging Operations and Environmental Research Programs ERDC SR-15-1 xxix DSAS Digital Shoreline Analysis System EA Environmental Assessment EAA European Environment Agency EGS Ecosystem Goods and Services ERDC U.S. Army Engineer Research and Development Center (CEERD) ESI NOAA’S Environmental Sensitivity Index ESMF Earth System Modeling Framework EWN Engineering With Nature FEMA Federal Emergency Management Agency FIFM-TF Federal Interagency Floodplain Management Task Force GAP USGS Gap Analysis Program GHG Greenhouse Gases GEV Generalized Extreme Value GIS Geographic Information Systems GNRA Gateway National Recreation Area HUC Hydrologic Unit Code HUD U.S. Department of Housing and Urban Development INA International Navigation Association IPCC Intergovernmental Panel on Climate Change IWR U.S. Army Engineers, Institute of Water Resources (CEIWR) JALBTCX Joint Airborne Lidar Bathymetry Technical Center of Expertise LIS Long Island Sound MASGC Mississippi-Alabama Sea Grant Consortium MHHW Mean Higher High Water MOA Memorandum of Agreement MOU Memorandum of Understanding ERDC SR-15-1 xxx MRLC Multi-Resource Land Characteristics Consortium MSL Mean Sea Level MSPA Morphological Spatial Pattern Analysis NACCS North Atlantic Coast Comprehensive Study NCMP National Coastal Mapping Program NDBC National Data Buoy Center NFIP National Flood Insurance Program NGO Non-Governmental Organization NJOCM NJ Office of Coastal Management NLCD National Land Cover Dataset NNBF Natural and Nature-based Features NOAA National Oceanic and Atmospheric Administration NPP Net Primary Productivity NPS National Park Service NSRE National Survey on Recreation and the Environment NVC National Vegetation Classification NWI National Wetlands Inventory O&M Operation and Maintenance PCA Principle Components Analysis PDT Project Delivery Team PIANC Permanent International Association of Navigation Congresses PWDCA Priority Wildlife Diversity Conservation Areas RG Recovery Goal RSM Regional Sediment Management SAME Society of Military Engineers SBAS Sediment Budget Analysis System SEDMAN Sediment Management Technologies SH Stakeholder SME Subject Matter Experts ERDC SR-15-1 xxxi SMSP Screening Methodology for Strategic Placement STWAVE Steady-state Spectral Wave Model SWAP NY State Wildlife Action Plan SWReGAP Southwest Regional Gap Analysis Project TES Threatened, Endangered, and Sensitive Species TNC The Nature Conservancy USACE U.S. Army Corps of Engineers USBLS U.S. Bureau of Labor Statistics USDA U.S. Department of Agriculture USEPA U.S. Environmental Protection Agency USFWS U.S. Fish and Wildlife Service USGS U.S. Geological Survey USNVC U.S. National Vegetation Classification VEVA Coastal Virginia Ecological Value Assessment VDGIF Virginia Department of Game and Inland Fisheries WAM WAve Prediction Model WAPA Western Area Power Administration WIS Wave Information Studies ERDC SR-15-1 1 1 An Introduction to Natural and Nature-Based Features (NNBF) and Their Use in Coastal Systems Overview Coastal systems are increasingly vulnerable to flooding due to the combined influence of coastal storms, development and population growth, geomorphic change, and sea level rise (Woodruff et al. 2013). This reality has given rise to efforts to make greater use of ecosystem-based approaches to reduce risks from coastal storms, approaches which draw from the capacity of wetlands, beaches and dunes, biogenic reefs, and other natural features to reduce the impacts of storm surge and waves (Temmerman et al. 2013). While the potential to apply ecosystem-based approaches to flood risk management will depend on the physical, geomorphological, and ecological context, examples of the importance and application of such approaches are increasing worldwide (Temmerman et al. 2013). Concepts and practices supporting today’s notion of NNBF have deep roots in the green infrastructure movement. This movement arose from environmental planning and conservation initiatives that go back over 160 years (yr), originating from the efforts of Frederick Law Olmsted, Warren Manning, and Eugene Odum, which were based on the realization that natural systems can deliver a range of ecosystem goods and services (Benedict and McMahon 2002, 2006; Ely and Pitman 2012). The range of activities captured by the term green infrastructure is based on the context of the problem, opportunity or objectives under consideration. For some, green infrastructure refers to open spaces or parks (Davies et al. 2006; Mell 2010; Mell et al. 2009); for others, it refers to engineered structures (e.g., storm water management features such as rain gardens1) that are defined as environmentally friendly; still other practitioners allude to the preservation of natural area networks (e.g., wetlands lined with riparian corridors) emphasizing the benefits of biodiversity and reductions in habitat fragmentation (Lafortezza et al. 2013; Wickham et al. 2010; Williamson 2003). In the context of the NACCS, green infrastructure is taking on a more coastal aspect (Edwards et al. 2013) focusing on coastal 1 http://water.epa.gov/infrastructure/greeninfrastructure/index.cfm#tabs-1 ERDC SR-15-1 2 and nearshore landscape elements (e.g., dunes, barrier islands) that provide the physical matrix that reduces flood damages and promotes resilience in the face of coastal hazards and threats of sea level rise. As such, the focus has turned toward the following definitions: The spectrum of relevant NNBF ranges from existing natural features (e.g., barrier islands, sand dunes, wetlands) to features that are the product of planning, engineering design and construction (e.g., a constructed wetland or a beach-and-dune system engineered for coastal storm damage reduction). In the context of the NACCS, the contribution of NNBF to engineering functions in the form of contributions to coastal resilience and storm risk reduction are a particular focus (USACE 2015). Natural, nature-based, nonstructural, and structural are thus terms used to describe the full array of measures that can be employed to support coastal Natural Features are created and evolve over time through the actions of physical, biological, geologic, and chemical processes operating in nature. Natural coastal features take a variety of forms, including reefs (e.g., coral and oyster), barrier islands, dunes, beaches, wetlands, and maritime forests. The relationships and interactions among the natural and built features comprising the coastal system are important variables determining coastal vulnerability, reliability, risk, and resilience. Nature-Based Features are those that may mimic characteristics of natural features but are created by human design, engineering, and construction to provide specific services such as coastal risk reduction. The combination of both natural and nature-based features is referred to collectively as NNBF. The built components of the system include nature-based and other structures that support a range of objectives, including erosion control and storm risk reduction (e.g., seawalls, levees), as well as infrastructure providing economic and social functions (e.g., navigation channels, ports, harbors, residential housing). ERDC SR-15-1 3 resilience and risk reduction (USACE 2013). Coastal systems include naturally occurring and built features in a socioeconomic context (McNamara et al. 2011). Natural coastal features take a variety of forms, including reefs (e.g., coral and oyster), barrier islands, dunes, beaches, wetlands, and maritime forests. NNBF can exist due exclusively to the work of natural processes or can be the result of human engineering and construction. The built components of coastal systems can include both nature-based and engineered structures that support a range of objectives, including erosion control and storm risk reduction (e.g., seawalls, levees), as well as infrastructure providing economic and social functions (e.g., navigation channels, ports, harbors, residential housing). The relationships and interactions among the natural and built features comprising the coastal system are important variables determining coastal vulnerability, risk, and resilience. Table 1 and Table 2 provide examples of natural and nature-based versus nonstructural and structural features relevant to coastal systems respectively, along with a listing of factors affecting the performance of these features. An integrated approach to coastal resilience and risk reduction will employ the full array of measures, in combination, to support coastal systems and communities. The NNBF study was undertaken to fill knowledge gaps and produce relevant information to support the identification, evaluation and integration of NNBF with structural and non-nonstructural measures in order to support coastal risk reduction and resilience. Developing a comprehensive framework was viewed as an important next step in coordinating the advancement of NNBF among the many organizations and stakeholders engaged in the management of coastal systems. ERDC SR-15-1 4 Table 1. Examples of NNBF relevant to coastal systems (USACE 2013). NATURAL AND NATURE-BASED FEATURES AT A GLANCE Dunes and Beaches Vegetated Features (e.g., Marshes) Oyster and Coral Reefs Barrier Islands Maritime Forests/Shrub Communities Benefits/Processes Breaking of offshore waves Attenuation of wave energy Slow inland water transfer Benefits/Processes Breaking of offshore waves Attenuation of wave energy Slow inland water transfer Increased infiltration Benefits/Processes Breaking of offshore waves Attenuation of wave energy Slow inland water transfer Benefits/Processes Wave attenuation and/or dissipation Sediment stabilization Benefits/Processes Wave attenuation and/or dissipation Shoreline erosion stabilization Soil retention Performance Factors Berm height and width Beach slope Sediment grain size and supply Dune height, crest, and width Presence of vegetation Performance Factors Marsh, wetland, or SAV elevation and continuity Vegetation type and density Spatial extent Performance Factors Reef width, elevation, and roughness Performance Factors Island elevation, length, and width Land cover Breach susceptibility Proximity to mainland shore Performance Factors Vegetation height and density Forest dimension Sediment composition Platform elevation General coastal risk reduction performance factors include: Storm surge and wave height/period, and water levels ERDC SR-15-1 5 Table 2. Examples of nonstructural and structural features relevant to coastal systems (USACE 2013). NONSTRUCTURAL STRUCTURAL Floodplain Policy and Management Flood-proofing and Impact Reduction Flood Warning and Preparedness Relocation Levees Storm Surge Barriers Seawalls and Revetments Groins Detached Breakwaters Benefits and Processes Improved and controlled floodplain development Reduced opportunity for damages Improved natural coast environment Benefits and Processes Reduced opportunity for damages Increased community resiliency No increase in flood potential elsewhere Benefits and Processes Reduced opportunity for damages Increased community resiliency Improved public awareness and responsibility Benefits and Processes Reduced opportunity for damages No increase in flood potential elsewhere Improved natural coast environment Benefits and Processes Surge and wave attenuation and/or dissipation Reduced flooding Reduced risk for vulnerable areas Benefits and Processes Surge and wave attenuation Reduced salinity Intrusion Benefits and Processes Reduced flooding Reduced wave overtopping Shoreline stabilization behind structure Benefits and Processes Shoreline stabilization Benefits and Processes Shoreline stabilization behind structure Wave attenuation Performance Factors Wave height Water level Storm duration Agency collaboration Performance Factors Wave height Water level Storm duration Performance Factors Wave height Water level Storm duration Performance Factors Wave height Water level Storm duration Performance Factors Levee height, crest width, and slope Wave height and period Water level Performance Factors Barrier height Wave height Wave period Water level Performance Factors Wave height Wave period Water level Scour protection Performance Factors Groin length, height, orientation, permeability, and spacing Depth at seaward end Wave height Water level Longshore transportation rates and distribution Performance Factors Breakwater height and width Breakwater permeability, proximity to shoreline, orientation, and spacing General coastal risk reduction performance factors include: Collaboration and shared responsibility framework, wave height, water level, and storm duration General coastal risk reduction performance factors include: Storm surge and wave height/period, and water levels ERDC SR-15-1 6 Natural and Nature Based Features (NNBF) Considered in this Report • Islands • Reefs • Beaches (sand, gravel, cobble) • Dunes / swale complex • Mudflats / sandflat • Submerged aquatic vegetation (seagrass, other - fresh or saline) • Salt marshes (emergent herbaceous) • Shrub-scrub wetlands (brackish) • Flooded swamp forests (brackish) • Bluffs (any material, if sand assume eroding dune) • Maritime grasslands • Maritime shrublands • Maritime forests • Riparian buffers • Emergent herbaceous marshes/wetlands (fresh) • Shrub-scrub wetlands (fresh) • Flooded swamp forests (fresh) • Ponds • Terrestrial grasslands • Terrestrial shrublands • Terrestrial forests Natural and nature-based features (NNBF) Natural features are created through the action of physical, geological, biological and chemical processes over time. Nature-based features, in contrast, are created by human design, engineering, and construction (in concert with natural processes) to provide specific services such as coastal risk reduction and other ecosystem services (e.g., habitat for fish and wildlife). Nature-based features are acted upon by processes operating in nature, and as a result, generally must be maintained by human intervention in order to sustain the functions and services for which they were built. Natural and nature-based features (NNBF) can be used to enhance the resilience of coastal areas threatened by sea level rise (Borsje et al. 2011) and coastal storms (e.g., Gedan et al. 2011; Lopez 2009). For example, beaches are natural features that can provide coastal storm risk reduction and resilience where their sloping nearshore bottom causes waves to break—dissipating wave energy over the surf zone. These breaking waves often form offshore bars that help to dissipate waves farther offshore. Dunes that back a beach can act as physical barriers that reduce inundation and wave attack to the coast landward of the dune. Although dunes may erode during a storm, they often provide a sediment source for beach recovery following storms. Engineered beaches and dunes can provide functions that are similar to natural beaches and dunes and represent nature-based infrastructure specifically designed and maintained to provide coastal risk reduction. These nature-based features often require beach nourishment to mitigate ongoing erosion and other natural processes. Supplying sand to the system ERDC SR-15-1 7 through beach nourishment, dune construction, and restoration reinforces risk reduction functions with respect to waves and storm surge. Coastal wetlands can attenuate waves and stabilize sediments, thereby providing coastal storm protection. Dense vegetation and the shallow water within wetlands can slow storm surge advance somewhat and can reduce the surge landward of the wetland or slow its arrival time (Wamsley et al. 2009a, 2010). Wetlands can also dissipate wave energy, potentially reducing the amount of destructive wave energy propagating on top of the surge. The magnitude of these effects depends on the specific characteristics of the wetlands, including the type of vegetation, its rigidity and structure, and wetland extent and position relative to the storm track. Although wetlands can retard storm surge propagation, water can be redirected, potentially causing a local storm surge increase elsewhere. Engineered and constructed wetlands act in the same manner as natural wetlands, though design features may be included to enhance risk reduction or account for the adaptive capacity of the wetland considering future conditions (e.g., by allowing for migration due to changing sea levels). In addition to providing engineering functions related to reducing risks from coastal storms, NNBF can provide a range of additional ecosystem services, including those supporting coastal ecosystems and communities. A true systems approach to coastal risk reduction and resilience requires consideration of the full range of functions, services, and benefits produced by coastal projects and NNBF. These include benefits related to commercial and recreational fisheries, tourism, provisioning of clean water, habitat for TES, and support for cultural practices. For example, breakwaters offer shoreline erosion protection by attenuating wave energy, but can provide additional recreational opportunities, valuable aquatic habitat, and carbon or nutrient sequestration. However, it is also important to recognize that there are interactions amongst features (i.e., structural, NNBF, and nonstructural) that could alter (either positively or negatively) the delivery of ecosystem goods and services. A systems approach to integrating these features intends to utilize positive interactions and minimize negative interactions. Natural features such as coastal wetlands, forests, or oyster reefs provide environmental and social benefits, but can also contribute to coastal risk reduction or resilience, as previously discussed. Nature-based features such as engineered beaches and dunes, or ecosystem restoration projects ERDC SR-15-1 8 involving coastal wetlands, forests, or oyster reefs, can provide a range of environmental and social benefits, including those related to coastal risk reduction. Combining NNBF with nonstructural measures may enhance the environmental and social benefits derived from these measures. The combination of these types of measures may reduce social vulnerability to changing sea levels and coastal storms, but some nonstructural actions can also allow for wetland migration over time or support increased benefits associated with recreation. Developing a more complete understanding of the ecosystem goods and services provided by the full range of coastal features, individually and in combination, will help to inform plan formulation and benefit determi-nation for risk reduction strategies. Some services are complementary, such as wetland restoration that increases habitat and wave attenuation, while others are conflicting, such as dune creation for risk reduction that competes with sightlines, raising viewshed concerns. As sea level rise and climate change influence the coastal environment, taking a comprehensive view of the services and benefits provided by an integrated combination of natural, nature-based, nonstructural, and structural features will provide important information for decision making that supports resilient coastal systems. Dynamic character of NNBF Coastal systems are naturally dynamic and NNBF respond in many ways to storms—with some responses being temporary and others permanent. Storm effects on wetlands often include erosion, stripped vegetation, and salinity burn—all of which can decrease long-term productivity (Michener et al. 1997). However, storms can also introduce mineral sediments that contribute to the long-term sustainability of wetlands with respect to sea level rise. The long-term consequences for wetland systems from hurricanes depends on many factors, including pre-storm landscape structure (including wetland extent and relationship to other natural and built features), proximity of the wetland to a storm track, and the meteorological conditions that persist following a hurricane (e.g., salinity burn effects are reduced if high precipitation occurs during or after the storm). Storms, the greatest source of coastal change on barrier islands, can produce water surge and strong waves. Surging water and stronger waves can erode barrier island beaches, and if the surge is high enough, result in overwash, breaching, or back-bay flooding, thereby reducing the storm damage reduction function of the islands. Over longer time scales, projections of sea ERDC SR-15-1 9 level rise show that low-lying areas such as wetlands and barrier islands presently seen as natural may require management and intervention if their ability to provide socially desired ecosystem services is to be retained. Performance with respect to objectives Knowledge about the performance of natural, nature-based, nonstructural and structural features varies, as do the methods to calculate and measure the performance of these features. Factors contributing to this variation include the diversity of objectives at play, the threats under consideration (e.g., a particular range or frequency of coastal storms), and the technical information that is available for describing the relevant processes and functions. Applying a systems approach to coastal risk reduction necessitates a rigorous scientific and engineering analysis of the performance of all system components while planning, designing, constructing, operating, maintaining, and adaptively managing the features comprising the system. The dynamic behavior and response of NNBF to threats such as coastal storms and development can affect their performance with respect to system-level risk reduction and resilience objectives. Moreover, it is important to design nature-based features in such a way that they will establish and/or re-establish natural processes and become as self-sustaining as possible. As a result, the coastal risk reduction and resilience services provided by these features will vary over space and time. For nature-based features such as engineered beaches and dunes, this variation can be addressed through effective planning and engineering to maintain the desired level of service. While some literature suggests that coastal features (e.g., wetlands and barrier islands) can reduce surge and waves, quantification of this performance has sometimes been based on limited data. This has resulted in widely varying characterizations of risk reduction benefits, from those based on anecdotal, qualitative, and quantitative information (Wamsley et al. 2009a). As a case in point, prior to Hurricane Katrina, the level of protection provided by wetlands had been empirically (but relatively simplistically) estimated with a simple rule-of-thumb. The actual ability of wetlands to provide protection from storms is complex and depends on many factors, including storm intensity, track, speed, and the surrounding local bathymetry and topography; simple rules-of-thumb may not take into account these complexities along a coastline and between storm events (Resio and Westerlink 2008). There are methods, however, for including these ERDC SR-15-1 10 complexities and the interactions of storms with NNBF that make use of more quantitative analytical approaches (Suzuki et al. 2012; Yao et al. 2012; Anderson et al. 2011; Cialone et al. 2008). Engineering With Nature (EWN) using NNBF The USACE initiative known as Engineering With Nature (EWN)1 promotes coastal resilience and sustainable development by advancing technical and communication practices that intentionally align natural processes with engineering design to efficiently and sustainably deliver economic, environmental, and social benefits through collaborative processes (Bridges et al. 2014). The tools and projects developed through the EWN program support planning, engineering, and operational practices that beneficially integrate NNBF into traditional engineering design to produce more socially acceptable, economically viable, and environmentally sustainable solutions. EWN is being pursued through innovative research, field demonstrations, communicating lessons learned, and active engagement with field practitioners across a wide range of organizations and business lines. The program’s intent is to develop practical methods that use an ecosystem-based approach to transform infrastructure development. By combining sound science and engineering with advanced communication practices, the EWN initiative is providing a robust foundation for collaborative project development using NNBF. The role of sound science and engineering Investment in the use of NNBF intended to provide ecosystem goods and services, including coastal risk reduction and resilience, should be based upon the best available scientific and engineering evidence about the function and performance of these features. Uncertainties regarding the performance of NNBF, frequently related to a lack of empirical data, present challenges to using nature-based infrastructure to reduce coastal risks. These uncertainties should be acknowledged and taken into account when evaluating, planning, and implementing NNBF as a part of actions taken to enhance the resilience of coastal systems. The need to reduce the uncertainties associated with evaluating and quantifying the value and performance of NNBF should be addressed through the coordinated action of relevant public and private organizations. The development of consistent technical approaches for evaluating and integrating NNBF with 1 http://el.erdc.usae.army.mil/ewn/ ERDC SR-15-1 11 structural and nonstructural approaches would help guide Federal and other investments in coastal systems. In addition to the practical science and engineering of NNBF (including the economics supporting these efforts), the social sciences are necessary to develop a comprehensive understanding of actions that can be taken to support coastal community resilience (e.g., McNamara et al. 2011). This includes social (technological, institutional, and behavioral) responses (Kates et al. 2012) and potential legal issues that can affect the implementation of NNBF (Craig 2010). Integration across these disciplines would enable the development of comprehensive solutions that include NNBF and address the needs of the natural, social, and built environments. This form of technical integration would help inform investments in coastal systems that produce sustainable societal benefits and coastal risk reduction over the long term. A framework for NNBF evaluation and implementation A framework was developed to support the evaluation and implementation of NNBF to achieve coastal risk reduction and resilience. Tools and methods for applying this framework are also being developed to support the application of the framework in the context of planning, designing, constructing, and evaluating NNBF within coastal systems. Chapters 2–7 of this document provide descriptions of the tools and methods under development. Figure 1 provides a graphical depiction of the overarching framework. The framework includes a range of activities relevant to the use of NNBF and is divided into three categories of activities: Organizational Alignment, Evaluation, and Implementation. One of the first steps to be undertaken in the process of identifying and analyzing NNBF opportunities is to align the organizations and interests relevant to a given geographic area, opportunity, or project. Projects employing NNBF are relevant to a diverse group of organizations and stakeholders. Public organizations have differing authorities relevant to NNBF. The interests of private organizations, including non-governmental organizations, in regard to NNBF include a broad range of objectives, from protecting private assets to securing specific environmental services. Identifying all the relevant authorities and interests germane to a given area or project and organizing communication about these authorities/interests is needed to appropriately frame the technical evaluation of NNBF. ERDC SR-15-1 12 Figure 1. NNBF evaluation implementation framework. The Evaluation component of the framework defines the NNBF alternatives under consideration, develops the technical information about how those alternatives are expected to perform, and culminates in the selection of specific alternatives (Figure 1). As depicted, the Evaluation process is intended to be flexible and iterative in order to satisfy the information needs of decision making and the selection of alternatives for implementation. The major activities comprising the Evaluation component of the framework are supported by tools and methods described in the following sections of this document: define the physical and geomorphic setting (Chapter 2); assess vulnerability and resilience (Chapter 3); identify NNBF opportunities (Chapters 2 and 3); evaluate NNBF alternatives (Chapters 3–5); and select NNBF alternatives. ERDC SR-15-1 13 The Implementation of NNBF includes design of an implementation plan, implementing the plan/alternatives, and then monitoring the performance of the implemented NNBF. Designing an implementation plan involves a range of engineering activities, including those related to the management and use of sediment resources that are used to construct or support NNBF (Chapter 6). Chapter 7 of this document describes a case study analysis of ecosystem goods and services associated with three NNBF projects within the NACCS project area. The results of performance monitoring are a source of information and feedback for future evaluations of NNBF. Looking forward Coastal systems provide important social, economic, and ecological benefits to the nation. However, our coasts are vulnerable to the influence of a combination of factors, including storms, changing climate, geological processes, and the pressures of ongoing development and urbanization. NNBF can help reduce coastal risks as a part of an integrated approach that draws together the full array of coastal features that contribute to enhancing coastal resilience. By employing sound science and engineering practices, collaborating organizations will be able to identify timely opportunities, formulate and evaluate robust alternatives, and implement feasible approaches for making use of NNBF to enhance the resilience of the social, economic, and ecological systems along our coasts. ERDC SR-15-1 14 2 NNBF Classification, Mapping, and Feature Characterization Overview Two existing classification systems in wide use were selected for classifying and mapping NNBF within the study area. The first is a geomorphologic classification of coastlines based on Shepard (1973), and illustrated in the Coastal Engineering manual (USACE 2002). The formation and the long-term sustainability of NNBF are driven by their geomorphology and landscape position—the basis for the Shepard classification system. Profiles were generated to illustrate the generic arrangement of geomorphic features, including NNBF for each of the geomorphologic classes present within the study area. Not all features presented in these profiles may occur at any given location. Geomorphic features commonly found in each coast type and the driving processes that create, sustain, and impact the feature are described in detail. Vegetation is often chosen as the basis for a single-factor system for classifying terrestrial ecological systems because it generally integrates the ecological processes operating on a site or landscape. Because patterns of vegetation and co-occurring plant species are easily measured, they have received far more attention than those of other components, such as fauna. Vegetation is a critical component of energy flow in ecosystems and provides habitat for many organisms in an ecological community. In addition, vegetation is often used to infer soil and climatic patterns. For these reasons, a classification based on vegetation can serve to describe many (though not all) facets of biological and ecological patterns across the landscape (Grossman 1998). The U.S. National Vegetation Classification (USNVC) (Grossman 1998) delivers a comprehensive, single-factor approach to ecological communities based on a hierarchical classification of vegetation. Geospatial mapping layers are available for the study area and descriptions of the plant communities are available through the State Natural Heritage programs (Table 6). ERDC SR-15-1 15 How to use these classification systems Coastlines are classified under Shepard (1973) based on the physical and geological processes responsible for the formation and present configuration of the coast. These processes (e.g., wave attack, erosion, sediment transport, sea level changes, glaciation) also continue to act on and shape both natural and manmade features in the coastal environment. Understanding these processes will be important to engineers and scientists for the design and construction of NNBF. The Atlantic coast within the study area from Chesapeake Bay to central Maine is classified according to the Shepard (1973) system; generic cross-sectional profiles accompany each class description. The profiles can be used to illustrate the types of NNBF (both natural and anthropogenic) that could be expected to occur and their position in the landscape, as well as how combinations of multiple features could be applied to increase the level of coastal protection afforded. Features and the processes that control their form and function are described separately. A detailed description of the plant communities in the NACCS study area has been compiled by the authors and is available upon request. The descriptions of the plant community associations can be used in a variety of ways. For example, knowledge of the species composition and structural characteristics of the vegetation could be used to estimate the degree of surface roughness and impedance to the flow of water. The descriptions of the species associations could also be used as a planting guide to select the most appropriate suite of plant species for coastal habitat restoration projects or identify areas vulnerable to salt burn. Mapping layers of the vegetation classes can also be used to identify areas of natural NNBF for conservation and preservation. Geomorphologic classification Background to coastal classification The Shepard classification system (1937, 1948, 1973) divides the world’s shores into primary coasts (formed mostly by non-marine agents) and secondary coasts (shaped primarily by marine processes). Further subdivisions occur according to which specific agent, terrestrial or marine, had the greatest influence on the coastal development. Although gradational shore types exist, which are difficult to classify, most coasts show only one dominant influence as the cause of their major characteristics (Shepard 1973) (Figure 2). ERDC SR-15-1 16 Figure 2. Shepard (1973) coastal classification hierarchy for the NACCS study area. Some major beaches in the Northeast are artificial, but because they behave like sand beaches with respect to coastal processes and biological communities, they are classified as barrier or beach plain rather than artificial. For example, Coney Island once consisted of three low islands that were joined and augmented with massive amounts of beach fill (Farley 1923). Jones Beach was created by the Long Island Park commission in the 1930s by dredging 40 million cubic yards (CY) of sand from South Oyster Bay and placing it among and over a group of low islands (Caro 1974; Hanc 2007). Nourished beaches, which include most of the Atlantic shore of Long Island as well and the Jersey shore, are classified as barrier coasts or beach plains, not as artificial. Atlantic Coast classification from Chesapeake Bay to central Maine The Atlantic coast of the northeastern United States is highly variable because of its geological history of Pleistocene glaciations and Holocene sea level changes. The region can be approximately divided at the mouth of New York Harbor. From New Jersey and southward, the Atlantic shore is a wave-dominated coast, where wave action shapes and modifies sand beaches and barrier spits. These extend for 10s or 100s of kilometers (km) and often enclose ponds or marshes. Sediments are almost totally derived from recycled continental shelf deposits or man-made deposition and can move by littoral transport for great distances or be entrained into tidal inlets. Rivers draining the Appalachians carry fine-grain sediment into estuaries (Chesapeake and Delaware Bays) or coastal ponds and marshes. Primary Coasts SecondaryCoasts Land erosion Subaerialdeposition Marine deposition Wave erosionOrganisms Volcanic Diastrophicmovements Drowned rivervalleys (rias) Drowned glacialerosion Glacial deposition Barrier coasts Shepard Classification of Coasts (1973)BeachplainsConfigured by nonmarine processesConfigured by marine processesPrimary configuration processNACCS study area coast typesERDC SR-15-1 17 Less than 5% of river sediment reaching the coastal zone is deposited on the continental shelf (Meade 1982). From Long Island northward, the geology changes significantly. Long Island and New England are a complicated paraglacial geological terrain that retains extensive surface cover of easily erodible glaciogenic sediments, with end moraine islands, drowned glacial valleys, sand spits, salt marshes, and bedrock outcrops (Hein et al. 2012). Some of the complex coastal morphologies found in this region include • barrier spits of southern Rhode Island, Cape Cod, Massachusetts Bay, Plum Island • glacial till bluffs of Block Island, Nantucket Island, Martha’s Vineyard, and islands in Boston Harbor • Narragansett Bay, a drowned glacial valley with a combination of bedrock outcrops, till bluffs, limited sand and gravel beaches, and limited salt marshes. Unlike the long barrier beaches of the mid-Atlantic, New England’s beaches are much shorter and usually bounded with a topographic feature such as a headland or channel. The south shores of Long Island and Rhode Island west of Narragansett Bay have the closest resemblance to the common Atlantic beach model of sandy beach/spit/pond complex. Many New England spits, such as the ones on the south shore of Martha’s Vineyard or southern Cape Cod, are the result of sediment derived from nearby eroding till bluffs. In much of Massachusetts, New Hampshire, and Maine, spits and beaches are more limited and often consist of pocket beaches with bounding bedrock headlands. Barriers typically average only 1 km in length (Duffy et al. 1989; Kelley 1987). The source of sand in these pocket beaches is a combination of locally derived material and minor input from rivers (Fitzgerald and Van Heteren 1999). For this study, the local topography at the water/land interface has been used as the primary factor in the classification with a scale of approximately 5 km (Figure 3). ERDC SR-15-1 18 Figure 3. Coastal classification for the NACCS study area. Coastal sediments in Connecticut were derived from glacial and early post-glacial sediments from within the Long Island Sound basin via storage, winnowing, and redistribution (Lewis and DiGiacomo-Cohen 2000). Northern New England is also different than the southern states in that this is the only area on the Atlantic seaboard where rivers bring sand directly to the open coast (FitzGerald et al. 2005). The coastal land forms within the study area can be classified with 5 of Shepard’s (1973) categories and the addition of an Artificial category: 1. Drowned River Valley (I A 1): Chesapeake and Delaware Bays 2. Drowned Glacial Erosional Coast (I A 2): Narragansett Bay 3. Glacial Deposition Coast (I B 2): North shore of Long Island, Connecticut, portions of Massachusetts 4. Marine Depositional Barrier Coast (II B 1): Atlantic shores of Long Island, New Jersey, Delaware, Maryland 5. Marine Deposition-Beach Plain (II B 3): Sections in New Jersey, Massachusetts, New Hampshire 6. Artificial (III): Manhattan Island, Boston, Logan and Kennedy Airports. One of the difficulties in applying a classification scheme to a complicated topography is deciding at what scale to apply different shore types. For example, the coast from Cape Cod to Boston Harbor is overall a drowned glacial deposition shore (I A 2), but within this zone, sand barrier (II B 2) extends from Scituate south to Plymouth and then from Sagmore (near the ERDC SR-15-1 19 Cape Cod Canal) west to Barnstable. The local topography determines how the shore responds to storms, its biological characteristics, and affects how local residents use the shore for recreation or residence. To begin the characterization process, the team developed idealized cross-shore profiles for each of Shepherd’s classes that occur within the region based on idealized topography, geomorphology, and commonly occurring vegetation communities. Given that this entire study area is highly developed, both NNBF and structural features have been included to illustrate how they might be distributed across the landscape on developed coastlines. An attempt was then made to locate example sites emulating these profiles to make a more direct connection between the classification and the on-the-ground features. The USACE Baltimore District (CENAB) then took this information and mapped the study area based on these classifications (refer to Appendix A). The following sections offer details for the profiles. I A 1 Drowned river valley General. Conceptual cross-shore profiles of this class are shown in Figure 4. Chesapeake and Delaware Bays are the prominent examples in this study area. Most of the shores consist of low banks and bluffs (typically less than 10 meters (m) high), marshes, short sand spits, beaches fronting the mainland (without ponds or marshes behind). Bluffs sometimes have narrow beaches along the waterline. Extensive portions of the shorelines have been armored (Benoit et al. 2007). Along the shores
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