Optimum combination of pond volume and outlet capacity of a stormwater detention pond using particle swarm optimization

Detention ponds are best management practices designed for the treatment and control of urban stormwater. Their design objectives are mainly to control the quantity and quality of urban stormwater at the minimum cost. However, tradeoff exists between these objectives and this call for optimization. Long term hourly rainfall data were analyzed and the rainfall characteristics were obtained. Analytical Probabilistic Models (APM) were employed and the model parameters were derived from the closest stations to the study areas. The APM parameters, along with catchment parameters, were used to develop optimal combination of pond volume and outflow that yield the minimum cost using the APM and Particle Swarm Optimization (PSO). Comparison of the PSO with APM shows that the PSO result is more accurate as it does not need discretization of outlet size. The PSO model was also found to be more robust, computationally cheaper and faster to implement.