Rainfall simulation as a tool for urban water quality research

This paper discusses the design of a rainfall simulator for undertaking urban water quality research. Currently there is limited understanding of many of the fundamental concepts relating to urban stormwater pollution. This can be primarily attributed to research studies being dependent on natural rainfall with its inherent high variability and the use of heterogenous urban areas. These factors can act as significant constraints to the transferability of research outcomes outside the study area. The proposed rainfall simulator has the potential to significantly enhance research outcomes, and has demonstrated its ability to successfully recreate the physical characteristics of natural rainfall. Rainfall simulation techniques used in agricultural research have been refined and made appropriate for use on paved surfaces. The procedures undertaken to calibrate its performance to match natural rainfall is described. It is important that the water used in the simulations is of a similar chemical quality to that of natural rainfall. This is because the chemical characteristics of rainfall can significantly influence the physicochemical characteristics of pollutants in runoff. A rainfall quality profile has been developed for the proposed study area using natural rainfall samples, and will form the basis for the chemical quality of the water used in simulations.