Identification of critical source areas for nonpoint source pollution in the Danjiangkou Reservoir Basin, China

Abstract

ABSTRACTZhuang Y, Zhang L, Du Y, Yang W, Wang L, Cai X. 2016. Identification of critical source areas for nonpoint source pollution in the Danjiangkou Reservoir Basin, China. Lake Reserve Manage. 32:341–352.Danjiangkou Reservoir is an important water source for the middle route of the South-to-North Water Diversion Project in China. Water quality is crucial for this project, and the identification of critical source areas (CSAs) plays a significant role in nonpoint source (NPS) pollution control. The load–area curve based on the Export Empirical Model was used to quantitatively classify CSAs of NPS pollution in the Danjiangkou Reservoir Basin as CSAs, sub-CSAs, and non-CSAs. About 70% of loads were from 30% of the basin. In CSAs, 45.4% of total nitrogen (TN) loads and 48.0% of total phosphorus (TP) loads were from 14.5% and 13.3% of the basin, respectively; in sub-CSAs, 19.7% of TN loads and 18.3% of TP loads were from 14.5% and 13.3% of the basin, respectively. CSAs of both TN and TP loads were mainly from areas near the reservoir, which are subject to severe soil erosion and large runoff discharge. In the Danjiangkou Reservoir Basin, we recommend a CSAs→sub-CSAs→non-CSAs hierarchical control in the NPS pollution management plan specifying that sloping farmland in Xichuan and Yunxian counties should be preferentially treated. The load–area curve offers a new way of identifying CSAs of NPS pollution and helps to establish effective control measures for NPS pollution.