Loss Characteristics of Non-point Pollutant from a Mixed Agriculture Watershed

Abstract

In order to explore the temporal and spatial variability of non-point source pollution in an agriculture watershed, the water quality and quantity characteristics of five flood events at Shuangqiao station in Siheshui watershed (south China) were monitored. Five pollutants, including BOD5, TSS, TP, TN, and NH3-N, were measured and analyzed. The characteristics of pollutant concentrations and load-transport rates were investigated. It is shown that the pollutant concentrations in the flood events are remarkably larger than those in the non-flood events. The temporal sequences of peak values between pollutant parameters and runoff flows are explored. It indicates that the time interval would be short if the high-intensity rainfall occurred in the initial period of a flood event. Most of the peak values of pollutant concentrations preceded the flow peaks. The correlation coefficients between TSS and other pollutant concentrations are analyzed. It is shown that there is a significant correlation between the concentrations of TSS and TP in the flood events.