DETENTION BASIN DESIGN USING CONTINUOUS SIMULATION.

A continuous simulation model is proposed for use in the design of detention basins. The model accepts standard National Weather Service hourly rainfall data as input. The hourly rainfall data may then be disaggregated into smaller time intervals using a built in empirical rainfall distribution model. A continuous runoff series for both the developed and pre-developed conditions is then generated using a continuous soil moisture accounting strategy and a nonlinear reservoir runoff model. For each individual storm a maximum peak discharge constraint is obtained based on the pre-development runoff series. The runoff series for the developed condition is then routed through a generic reservoir from which a series of required storages may be obtained. The final output from the model includes both peak discharge and required storage frequency curves from which design decisions can be made.