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|Title:||Accessing and using meteorological data to evaluate wetland hydrology|
|Authors:||University of Texas. Bureau of Economic Geology.|
Wetlands Regulatory Assistance Program (U.S.)
Sprecher, S. W.
Warne, Andrew G.
|Publisher:||Environmental Laboratory (U.S.)|
Engineer Research and Development Center (U.S.)
Abstract: The Corps of Engineers Wetlands Delineation Manual recommends that “preceding weather conditions must be considered” when interpreting observations of water at possible wetland sites. Sources of meteorologic information are described in this report, and suggestions for analysis of relationships between local and regional weather and site hydrology are provided. Monthly precipitation data from more than 8,000 National Weather Service (NWS) stations have been analyzed, compiled, and made available on the Internet by the USDA National Water and Climate Center in the format of WETS Tables. These tables report 30th and 70th percentile exceedence frequencies for monthly precipitation, which generally define the range of normal precipitation. Suggestions for presentation of WETS Table data are provided. A method for calculating rolling sums of daily rainfall to enhance the accuracy of hydrologic assessments of sites is presented. The USDA Natural Resources Conservation Service has devised a method for systematically assessing antecedent weather conditions at a site; this method is described and suggestions to enhance the accuracy of this approach are provided. Regional patterns of drought and precipitation excess can be tracked using the Palmer drought indices, the Standardized Precipitation Index, and/or real-time gauge data. Contemporary conditions are standardized as percentiles of long-term records at Web sites reporting these analyses for climate divisions in each state. The statistics of precipitation frequency analysis and some of the pitfalls in using site-specific and regional data are discussed. Analyses of regional precipitation patterns are probably sufficient when observations of hydrology are not quantified. Personnel engaged in projects requiring quantification of onsite hydrology, however, should gather precipitation data on or close to the site on a daily basis. Daily data not gathered from official NWS stations should be compared with daily records from stations included in the WETS Tables network. These analyses should then be superimposed on the long-term patterns available from Web sites reporting regional analyses of climate divisions.
|Rights:||Approved for public release; distribution is unlimited.|
|Appears in Collections:||Technical Report|