[Parameter identification and validation of SWMM in simulation of impervious urban land surface runoff]

The purpose of this paper is the application of storm water management model (SWMM) in simulating runoff hydrology and water quality. The study chose a roof as the typical impervious urban land surface, and monitored several rainfall-runoff events for parameter identification. We identified and validated hydrological and water quality parameters, using Monte Carlo sampling method and HSY algorithm, which are based on uncertainty analysis. Results show that impervious urban land surface runoff model includes 6 critical parameters, which are depression storage (S-imperv), Manning's n (N-imperv), maximum buildup possible (max buildup), buildup rate constant (rate constant), washoff coefficient (coefficient), and washoff exponent (exponent). Identification of S-imperv and N-imperv could use least square error as objectives, while others could use errors of event pollution load and peak concentration of pollutant as objectives. The identification results of the 6 parameters are N-imperv 0.012-0.025,S-imperv 0-0.7, max buildup 15-30,rate constant 0.2-0.8,coefficient 0.01-0.05, and exponent 1.0-1.2. Regional sensitivities of these parameters in non-ascending order are coefficient, S-imperv, N-imperv, max buildup, exponent, and rate constant. Identified parameters are able to be validated by SWMM model. However, current model structures still have some difficulties in simulating runoff pollutant concentration curves caused by some special rain patterns.