Study Of Water Quality And Pollution Characteristics From Courtyard Rainfall Runoff In A Rural Township

Water shortage is a global problem. The rain water is being extended gradually as cost-effective water resource. China is a large agricultural country. The rural areas are shorter of water resources compared to urban areas. Research about rural runoff feature and runoff water quality analysis has also become interesting.After investigating many literatures and a large number of application examples, our study selected two typical Beijing villages as the research objects. We monitored the water quality and concentrations of pollutants of roof and courtyard rainfall runoff which were collected in 10 rainfall events in rainy season of 2009-2010.Our study analyzed the main types of pollutants, concentration range, particle size distribution and various pollutants indexes and their dependency rules in roof runoff and courtyard runoff. We calculated mean concentrations and pollution load in roof and courtyard rainfall events on the basis of these data. Meanwhile, we investigated the initial flushing effect of the roof and courtyard rainfall runoff and proposed the reuse methods of roof and courtyard rainfall runoff.The quality of roof runoff water can meet quality standards of water for life and landscape added water.SS is the main pollutant that caused pollution of roof runoff. The mean EMC value of TP, TN, SS and COD in roof runoff is 0.057mg/L,4.195mg/L, 49.124mg/L,28.517mg/L, respectively. The initial flushing effect is widespread in roof runoff pollution of villages. SS is obvious in the initial flushing effect of the roof runoff. The early runoff which is 30% of the total runoff migrated contaminants whose mass is 69.7% of total suspended particulate matter. The water quality of courtyard rainfall runoff is bad, thus cannot meet the quality standards of water for life. SS is also a major pollutant in the courtyard runoff. The mean EMC value of TP, TN, SS and COD in hardened courtyard runoff is 21.53mg/L,38.289mg/L,8.353mg/L,1.141mg/L, and the mean EMC value of TP, TN, SS and COD in semi-hardened courtyard runoff is49.02 mg/L,154.983 mg/L,6.831 mg/L,0.704 mg/L. The concentrations of SS and COD are much lower in hardened courtyard compared to semi-hardened courtyard. Initial flushing existed in courtyard runoff, but the initial flushing effect is not obvious in semi-hardened courtyard.Rainwater can be stored using roof collection system in single village courtyard and can be used as toilet flushing, greening water and landscape recycling water after simple sedimentation process. The quality of runoff water in hardened courtyard is good and can be collected through pipe system as recycled water after simple sedimentation process. Runoff water in semi-hardened courtyard is bad in quality and runoff is also less so that can be discharged into drains and used as landscape added water together with road runoff water.