Hydrologic Modeling of Detention Pond

Urban watersheds produce an instantaneous response to rainfall. That results in stormwater runoff in excess of the capacity of drainage systems. The excess stormwater must be managed to prevent flooding and erosion of streams. Management can be achieved with the help of structural stormwater Best Management Practices (BMPs). Detention ponds is one such BMP commonly found in the Austin, TX, USA. The City of Austin developed a plan to mitigate future events of flooding and erosion, resulting in the development and integration of stormwater BMP algorithms into the sub-hourly version of SWAT model. This paper deals with the development of a physically based algorithm for detention pond. The algorithm was tested using a previously flow-calibrated watershed in the Austin area. From the test results obtained it appears that the detention pond algorithm is functioning satisfactorily. The algorithm developed could be used a) to evaluate the functionality of individual detention pond b) to analyze the benefits of such structures at watershed or higher scales and c) as design tool.