Sensitivity Study of Detention Basins in Urbanized Watershed

Abstract

The use of stormwater detention basins in urbanizing areas does not guarantee that downstream runoff peak flows will remain below their predevelopment levels for a given rainfall event. The purpose of this study is to provide a detailed hydrologic investigation of an urbanizing watershed to evaluate the effects of on‐site detention of stormwater runoff. The analysis was based on the 10‐yr design storm. The 10‐yr rainfall event was used to model the runoff response of the North Loomis basin at the headwaters of Antelope Creek. Detention basins were designed to control peak postdevelopment flow rates to 100% peak predevelopment flow rates. The results confirm that the siting of detention basins needs to be determined on a watershed—rather than a subarea—basis. In addition, the historic runoff route, left in a greenbelt condition, can be effective in controlling the urbanized peak runoff rate.