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|Title:||Characterization of anaerobic chemical processes in reservoirs : problem description and conceptual model formulation|
|Authors:||Environmental and Water Quality Operational Studies (U.S.)|
Brannon, James M.
Water quality models
|Publisher:||Environmental Laboratory (U.S.)|
Engineer Research and Development Center (U.S.)
Abstract: The occurrence of dissolved oxygen depletion and anaerobic processes in the hypolimnion of Corps of Engineers (CE) reservoirs can adversely impact water quality and directly affect CE Civil Works activities. A literature review, a consultation with authorities on anaerobic systems, and a workshop indicated the feasibility of developing a conceptual model to depict major pathways for nutrient regeneration and metal mobilization under anaerobic conditions. The product of subsequent model development and experimental studies, Dissolved Oxygen Subroutine with Anaerobic Processes (DOSAP), is presented herein and its operation is described in detail. The DOSAP model is presented as a series of seven linked geochemical steps (phases) of increasingly anaerobic (reduced) conditions. Major factors influencing the rate and duration of each of the major pathways are discussed. The DOSAP model has subsequently been transformed into a mathematical subroutine for the CE one-dimensional reservoir water quality model, CE-QUAL-R1. A literature search revealed a paucity of information on various physicochemical and biological rates affecting geochemical/water quality conditions in reservoirs, although abundant data for some parameters exist for other freshwater systems and marine environments. A series of investigations conducted in 250-𝓁 laboratory reaction chambers provided an initial set of physicochemical rate data for DeGray Reservoir on the Caddo River in Arkansas. Use of large reactor systems appears to be a feasible approach for obtaining the physicochemical rate data required to use DOSAP on a site-specific basis, and this method is being used to develop a set of rate coefficients using sediments from CE reservoirs on a nationwide basis. While detailed guidance on data requirements, sampling procedures, and rate coefficient selection for DOSAP will be presented in a later Engineering Technical Letter, this report summarizes procedures currently being used to obtain data for the subroutine.
|Appears in Collections:||Technical Report|