Abstract
The source area of Liao River is a typical cold region in northeastern China, which experiences serious problems with agricultural nonpoint source pollution (NPS), it is important to understand future climate change impacts on NPS in the watershed. This issue has been investigated by coupling semi distributed hydrological model (SWAT), statistical downscaling model (SDSM) and global circulation model (GCMs). The results show that annual average temperature would rise by 2.1 °C (1.3 °C) in the 2080 s under scenario RCP8.5 (RCP4.5), and annual precipitation would increase by 67 mm (33 mm). The change in winter temperature and precipitation is most significant with an increase by 0.23 °C/10a (0.17 °C/10a) and 1.94 mm/10a (2.78 mm/10a). The future streamflow, TN and TP loads would decrease by 19.05% (10.59%), 12.27% (8.81%) and 10.63% (6.11%), respectively. Monthly average streamflow, TN and TP loads would decrease from March to November, and increase from December to February. This is because the increased precipitation and temperature in winter, which made the spring snowpack melting earlier. These study indicate the trends of nonpoint source pollution during the snowmelt period under climate change conditions, accordingly adaptation measures will be necessary.
Highlights
Nonpoint source pollution (NPS) is a great concern due to its impacts on water environment pollution and water quality deterioration
After the Soil Water Assessment Tool (SWAT) model is established by carrying out sensitivity analysis on the snowmelt parameters, the model is applied to assess the impact of future climate change on the streamflow and the nutrients loads under two scenarios (HadGEM3 RCP4.5 and RCP8.5)
The statistical relationship between large-scale weather predictor factors and regional meteorological factors in the source area of Liao River was found by using statistical downscaling model (SDSM)
Summary
Nonpoint source pollution (NPS) is a great concern due to its impacts on water environment pollution and water quality deterioration. The snowmelt by winter snowfalls contributes considerably to water resources in these cold areas, and supplies a concentrate amount of nonpoint source nitrogen and phosphorus pollutants during spring period[6]. Crossman (2013) applied the coupled model of HBV and INCA-P to forecast the impact of climate change on phosphorus migration and transformation in the Black River basin in Canada, the results show that the future precipitation and temperature will increase, so that the total phosphorus load shows an increasing trend, especially in winter[17]. This study attempts to analyze the change of nonpoint source pollution loads during annual and snowmelt period in the source area of Liao River under different climate change scenarios using SWAT model, SDSM and GCM.
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