Methodology for Calibrating Stormwater Models

A method for calibrating coupled quantity-quality stormwater management model is presented. The United States Environmental Protection Agency Storm Water Management Model is used as an example. Quantity and quality subroutines are separated and each is calibrated using measured data. Data from six storm events are used for quantity calibration and data from five storm events are used for quality calibration. Model parameters are adjusted, based on sensitivity analyses, until predicted and measured outputs are within stated calibration criteria. The calibrated models are then recombined and the coupled model is used to predict annual pollutant loadings. Loading rates are compared with loading rates predicted using a single storm event calibrated model.