Study On The Response Of Nitrogen And Phosphorus Pollution In The Upper Reaches Of Hunhe River Under The Background Of Climate Change

Due to the increasing global warming caused by climate change,the global water environment has been damaged to varying degrees.Under the background of global climate change,the spatial and temporal distribution of climatic factors such as rainfall and temperature will inevitably lead to changes in the water cycle process and its ecological environment.At the same time,the strong influence of human activities has caused the confluence mechanism of the basin to change,which in turn has caused changes in the basin water environment.As a typical surface ecological process,non-point source pollution is influenced by natural factors such as hydrometeorology and human factors.On August 16,2013,Fushun experienced a large-scale rainstorm and floods.The floods caused nutrient salts to flow into the reservoir,causing complex physical,chemical,and biological changes in the water resources in the basin,which exceeded the self-purification scope of the water body and seriously affected the water quality of the Dahuofang Reservoir catchment area.The Dahuofang Reservoir catchment area is a water Conservancy hub with multiple functions such as water supply,flood control,irrigation,power generation,and aquaculture.According to statistics,non-point source pollution has become an important factor affecting the water quality of the Dahuofang Reservoir catchment area.Therefore,to explore the impact of climate change on non-point source pollution in the catchment area of dahuifang reservoir can further improve the application system of water quality simulation,help to improve the water quality in the catchment area of dahuifang reservoir,build a water quality warning system for the catchment area of dahuifang reservoir,and formulate water pollution prevention countermeasures.Taking the catchment area of the dahuifang reservoir as the research area,this paper studies the response of non-point source pollution process to climate change from the angle of climate change.Based on the 50-year measured meteorological data of the basin,the future climate change scenario of the research area was predicted by the global climate model GCMs,NCC/GU-WG weather generator,and the trend of non-point source pollution load change was simulated with the SWAT model.The main contents and conclusions of the study are as follows:(1)Based on the SWAT model,this study establishes the SWAT model database of the catchment area of Dahuifang Reservoir,analyzes the sensitive factors,determines the model rate,and verifies the model.The SWAT model is applicable to the catchment area of Dahuifang Reservoir and can simulate the hydrologic change process.The results of pollution load simulation show that during the simulation period,the TN and TP load decreased with the change of rainfall in 2006-2007,indicating that rainfall has an important influence on the time distribution of non-point source pollution.The effect on TN load output is significantly greater than that of TP load.The spatial distribution of TN and TP loads is affected by the combined effects of rainfall and land use.(2)Climate change in future years in regions modelled on the GCMs global climate models A1,B1 and NCC/GU-WG scenarios,combined with SWAT models to predict non-point source pollution load responses under climate change conditions.The trend of future precipitation and temperature changes in three kinds of climate scenarios is basically the same,and both are increasing.Under the influence of climate change,the TN load and TP load changes in the catchment area of Dahuifang Reservoir also show an increasing trend in the next year.The average increase of TN and TP load is relatively small,but the annual fluctuations are large.(3)This study uses the SWAT model as the basis to establish the SWAT model database of the Dahuofang Reservoir catchment area,analyze the sensitivity factor of the model,model rate determination and verification.The future climate scenario will be used as the climate port of the SWAT model to simulate the change of water quality in the next 30 years.During the forecast period of 2021-2050,the TN and TP in the study area showed an increasing trend,and the increase of TP was significantly lower than that of the TN load.TP has the largest inter-annual volatility,and TP volatility is higher than the interannual volatility of TN load.