Analysis of Non-Point Source Pollution Features of Chao River Basin Based on the CMADS-Driven SWAT Model

Abstract

By the China Meteorological Assimilation Driving Datasets for the Soil and Water Assessment Tool (SWAT) model (CMADS 1.0), this paper simulated the non-point source (NPS) pollution of Chao River Basin in the upper reach of Miyun Reservoir, and analyzed the spatial-temporal distribution pattern of nitrogen and phosphorus pollutants and the contribution rates of pollution sources. The major findings of the research are as follows. The CMADS V1.0-driven SWAT model shows good applicability to the study area. The simulation of the runoff, nitrogen and phosphorous pollution in the calibration period and the validation period has yielded a Nash-Sutcliffe efficiency (Ens) coefficient at 0.51~0.78, and a coefficient of determination at 0.73~0.88, which meets the model evaluation standards. The total nitrogen (TN) and total phosphorus (TP) pollution load in the flood season is considerably large, and the average inflow of TN and TP into the reservoir accounts for 60.62% and 75.15% the total annual inflow, respectively. The #26 sub-basin marks the biggest TN and TP loads, and it is thus worth more attention from pollution control administrations. Overall, the TN and TP load in the lower reach of the basin are larger than the upper reach. NPS pollution is the major type of pollution caused by human production and life. The livestock and poultry farming as well as fertilizers, which are the main contributors to NPS pollution, are considered the focus of NPS pollution control.