Accuracy of a Stormwater Monitoring Program for Urban Landuses

Abstract

This study examined the accuracy of an urban stormwater monitoring program in estimating the annual discharge load (L-T) and the annual reduction rate by a stormwater treatment device (R-T) for total suspended solids. A calibrated stormwater management model was used to generate the entire stormwater runoff events in one year and was used to estimate L-T and R-T under different monitoring strategies having limited numbers of runoff events, including random, wet season, antecedent dry days (ADD)-based, monthly, and seasonally weighted. For random monitoring, 12 storms were required to estimate the values of L-T and R-T with mean relative errors of 13.98 and 0.24%, respectively. Monthly monitoring had slightly greater mean relative errors compared to random monitoring. Wet season and ADD-based monitoring under-or overestimated both L-T and R-T. Monitoring with equal numbers of storms from the wet and dry seasons best estimated L-T and R-T.