Surface runoff and pollutants characteristics of inflowing rivers in the agricultural and phosphorus-rich region on the southeast coast of the Lake Dianchi

LI Farong,QIU Xueli,ZHOU Jing,LIU Yong*,LIU Shuchun*,GUO Huaicheng

Abstract: The characteristics of surface runoff and pollutants loss in the rivers which flowing into the lake is the foundation for analyzing the external input and the spatio-temporal distribution of pollutants for lakes and other water bodies. Based on eight times monitoring, this study analysed the characteristics of surface runoff and pollutants loss in 10 rivers on the southeast coast of Lake Dianchi. Water quality of these rivers are mainly influenced by agricultural non-point source and phosphate exploitation. In order to explore the characteristics of pollutants loss during rainfall events, three rivers which have the same rainfall process on the south coast of Lake Dianchi were selected for rainfall−runoff monitoring. The results showed that the mean discharge of Xinbaoxianghe river was 2.6 m3•s-1 which occupied 26.5% of the total discharge flowing into the lake. TN、TP、COD and SS which had seriously exceeded standard values in many rivers were the major load for Lake Dianchi pollution. River water quality could be classified into three classes and showed a significant spatial differentiation. The contribution rate of TN、TP、DP and NO3−−N was 53.636%. This showed the quantity of N and P was the main contribution factors to river pollution. The concentration of COD and SS could increase rapidly especially during rainfall. Discharge and SS had correlation to most water quality indicators. The influence of phosphate exploitation on river were more obvious during rainfall, its concentration of SS during rainfall could be 1.9 times higher than rivers which only influenced by agricultural non-point source.
Key words: Agricultural Non-Point Source Pollution;Surface Runoff;Loss Characteristics;Spatial Differentiation;Lake Dianchi