Safe Yield Study for Lakes Maumelle and Winona
Little Rock, Arkansas
FTN conducted a study to determine the safe yields for Lakes Maumelle and Winona, which serve as the raw water supplies for Little Rock Municipal Waterworks. To achieve the study objectives, FTN researched available data and previous reports, collected available data, performed basin analyses and hydrograph analyses, prepared inflow hydrographs for the reservoirs, prepared a simulation model, and performed reservoir routings for various yields to determine the maximum yield available with existing storage. For the study, safe yield was defined as the minimum runoff from a watershed that can be collected for use.Basin analyses addressed physical characteristics of the contributing watersheds, soil types, land uses and hydrologic parameters. For the hydrograph analyses, inflows into Lake Maumelle and Lake Winona were determined using regression analysis with nearby basins. This method was chosen over rainfall-runoff analysis because available flow data are believed to be more reliable. A reservoir routing model was prepared to perform storage routing for the lakes. The model accounted for inflows, water supply releases, net evaporation on the pools, and leakage. An engineering report was prepared and submitted to the client presenting the results of the various analyses and the safe yields determined from the study. Additionally, recommendations were made regarding data collection needs that would improve the reliability of future studies.
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