Estimation of storm runoff loads based on rainfall-related variables and power law models – Case study in Alexandra

Abstract

This paper compares the use of simple regression equations of three commonly used pollutant build-up and wash-off
functions, namely linear, power and exponential functions, to estimate event pollutant loads. The comparative study indicated that, event loads are better estimated as power functions of storm-related independent variables. On the notion that rainfall data are more readily available, easy and less expensive to collect than runoff data, the calibrated model was verified using rainfall volume as independent variable. The verified model was then used to develop load-duration-intensity curves to serve as predictive tools. Planners and engineers can use these predictive tools to obtain an approximate estimate of event pollutant
loads in storm runoff from Alexandra (and also other townships with similar physical, land-use, climatic and hydraulic
characteristics and water quality issues) for the purpose of managing or improving drainage conditions in the township.

Water SA Vol.32 (2) 2006: pp.1-8