Study On The Change Of Hydrological Regime In Dongjiang River Basin Based On SWAT Model

As an important material basis for the survival and reproduction of human society,water resources are seriously interfered by external factors.In particular,surface runoff,as an important component of water resources,has been affected by climate warming,land cover change and pollutant enrichment caused by the rapid economic and social development.As a result,the hydrological situation has changed significantly,resulting in a series of water resources problems such as the contradiction between social supply and demand of water resources,water environment pollution and river ecological environment deterioration.It is of great significance to clarify the evolution law of hydrological regime,quantify the influence of human activities,and regulate human behavior to solve the current water security problem and maintain the harmonious coexistence between human and nature.Therefore,this study takes Dongjiang River Basin in Guangdong Province as the research object.Based on Arc GIS software and SWAT model,this study uses digital elevation data,land use data,meteorological and hydrological data,soil data,etc.,to study the response mechanism of hydrological regime in Dongjiang River basin to reservoir operation under the same climate and land use background.The results are as follows:（1）The SWAT model of Dongjiang River Basin was constructed,and the measured runoff data of Boluo Station,a controlled hydrological station of Dongjiang River,was used to determine and verify the model.The results of calibration verification show that R²=0.82,E_NS=0.81 in the rate period and R²=0.80,E_NS=0.65 in the verification period,both meet the accuracy requirements of the model simulation.（2）Based on the SWAT model of Dongjiang River Basin,the influence of the operation of three reservoirs on the runoff process under the dam and Boluo station section is analyzed.The results show that the flow of control section changes significantly after reservoir regulation and storage.In terms of the median monthly discharge,the average monthly discharge in flood season showed a decreasing trend compared with that before the reservoir was in operation,while the average monthly discharge in non-flood season showed an increasing trend.（3）The hydrologic regime of Boluo Station changes to some extent under different reservoir regulation scenarios.The operation of Xinfengjiang reservoir has huge influence on Boluo hydrographic Station.Under the condition of double reservoir operation,the combined operation of Fengshuba and Baipenzhu dual reservoir has the least influence on Boluo Station,while the combined operation of Fengshuba and Xinfengjiang,Baipenzhu and Xinfengjiang dual reservoir has the same influence on Boluo Hydrographic Station.The overall hydrological change of Boluo station under the operation of different number of reservoirs is a tremendous change,and the overall hydrological change degree of Boluo station increases with the increase of the number of reservoirs.（4）By changing the monthly minimum discharge of the reservoir,this paper discusses the influence of the ecological discharge guarantee mode on the Dongjiang River hydrological regime.The results show that:with the increase of the monthly minimum discharge of the reservoir,the number of hydrological indicators that change the height of the three Dams and Boluo station increases,and the greatest change of Xinfengjiang Dam is the most obvious.In addition,the overall hydrological variation of the three Dams and Boluo stations also increases with the increase of the monthly minimum discharge.