Several parameters, such as the type and area of the catchment, the characteristics of the rain, can influence the pollutant characteristic and first flush effect of runoff in combined sewer system.

• 合流制排水系统降雨期间高污染溢流污水直接排入水体对水体质量有明显影响,其径流污染物输出特征和初期冲刷效应受排水区类型、面积、降雨特性等多种因素影响。