Stormwater Detention in Developing Watersheds

A method for evaluating the effects of subdivision scale detention storage basins on watershed hydrologic and water quality response is identified and applied to a developing watershed in Houston, Tex. Data used in the modeling efforts were obtained from historic flow records and measured storm pollutant concentrations. Reductions in peak flows and sediment export provided by various sizes of detention basins are analyzed by the model STOREME for 200-acre (80-ha) developed areas. The results indicate that storage volumes on the order of 30%-60% of the runoff volumes can reduce flood peaks to predevelopment levels. Sediment removal efficiencies in the basins are between 90% and 100%. Analysis of various levels of storage controls on different frequency storms suggests that an optimum control level exists. The results are extended to define the overall watershed response for different land uses in Keegans Bayou.