| With the development of urbanization and the deterioration of surface water quality, pollution caused by village surface runoff also attracted intensive environmental concerns. Village rainfall runoff is one of the important pollution sources influencing the quality of receiving waters. However, there is little research in this area so far in our country.Da Niufang and Yu Lin were selected to investigate the characteristicrs of pollution discharging such as rainfall runoff water quality and quantity. In combination with rainfall process data, the features of rainfall runoff, pollution and the affect on receiving waterbodis were measured. The type and concentration of major pollutants in runoff water, particle size and settlement characteristics of particulates, the correlation of various kinds of water quality indexes were determined, on which the averages of event mean concentration (EMC) and pollution load were calculated. The characteristics of pollutants discharged in rainfall runoff and the effect of the first flush were studied. Flush model and receiving waterbody quality changing model were proposed as well.Results showed that the averages of event mean concentration (EMC) of Da Niufang for TP, TN, COD and SS were 0.11,3.09,1684.27 and 285.83 mg/L, while the values for Yu Lin were 0.37,4.73,281.97and 72.57mg/L, respectively. Rainfall runoff from village exhibited moderate first flush effect, and 40 to 50 percent of the total pollutant loads were transported by the initial 30 percent volume of the runoff. The rule of surface runoff flush accords with general erosion model, and fits well withC1=C0e-K·1. The flush coefficient K is influenced by rainfall intensity, the surface properties of remit, pollutants properties and other comprehensive factors. Surface runoff has significant impacts on pH, SS, COD and other indicators of receiving waters, but the quality of receiving water can be restored to the original state within 48 hours as shown in this research. |
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