Storm water samples collected from an urban road in Xi′an City show that the urban road surface runoff has much greater pollution intensity of SS and COD and possess less biodegradability.

Storm drainage, even though the water may enter watercourses by way of pipes or channels, is considered nonpoint source pollution.

For water and soil conservation and water pollution control, it is very important to simulate and predict the yield of sediment and pollutant during storm-runoff.