Prediction of Nitrogen Emission in the Upper Reaches of the Huai River Basin Under Climate Change Scenarios

The Huai River Basin is an area where water bodies are seriously polluted by nutrients. Using data from the Huaibin Basin in the upper reaches of the Huai River as the study area, we created the SWAT model for the study area firstly. And then calibrated and validated the SWAT model against the monthly runoff and ammonia nitrogen concentration measured at Huaibin hydrological station from 2011 to 2017. At last, the potential impact of climate change on the runoff, ammonia nitrogen concentration and non-point source total nitrogen load under different climate change scenarios (RCP2.6, RCP4.5, RCP6.0, RCP8.5) in the 30 years (2020-2029, 2030-2039, 2040-2049) were predicted based on the climate data from Global Climate Model as the model input. The study found that the Nash-Suttcliffe coefficient of the runoff during the calibration period and the validation period were both 0.79, and the Nash-Suttcliffe coefficients of the ammonia nitrogen during the calibration period and the validation period were both higher than 0.5, so the applicability of the model was generally good. The main factors affecting the spatial stratified heterogeneity of nitrogen load were the amount of fertilization and the type of land use. The prediction of the Huaibin Basin indicated that before 2049 precipitation and temperature will increase under different climate change scenarios. If the current status of pollution emissions unchanged, the total nitrogen load from non-point source in the basin will increase by up to 31.8%, while the annual average ammonia nitrogen concentration at the outlet of the basin located at the Huaibin hydrological station will decrease by up to 42.6%. The study can provide scientific support for making basin management policies under the pressing challenges from climate change in the future. © 2022, Science Press. All right reserved.