Impacts Of Land Use Change On Runoff In Qingshui River Basin

Land use change is an important factor that causes changes in river runoff.The Yongding River-Yanghe section is located in the Haihebei system and is a key watershed for water quality improvement and water pollution control in the Guanting reservoir basin.Improvement of its water quality will lay a solid foundation for water quality improvement in the Haihe River Basin.basis.As an important tributary of the Yanghe River,the Qingshui River is relatively fragile in its ecological environment,and its economic development will inevitably bring great impact on land cover,water volume,and water quality.The study area is Qingshui River,Chongli District,Zhangjiakou City.With the support of GIS technology,the SWAT model is used to simulate the impact of land use change on runoff,and the runoff changes under land use change are analyzed.Simultaneously,different land use types are simulated and calculated.The impact coefficient of river basin production and flow provides a scientific basis for the river basin water environment control and soil and water conservation control work.The main research contents and results of this paper are as follows:(1)From 1990 to 2015,the land use types of Qingshui River basin in Chongli area were mainly woodland,grassland and cultivated land.The total area of the three land use types accounted for more than 96%of the total area of the basin.In the past 25 years,the vegetation coverage in the watershed has decreased.The slope and slope distribution characteristics of different land use types in this area are consistent.(2)Collect and arrange the meteorological,hydrological,soil and land-use data of Chongli area,establish the spatial database and attribute database needed for operation of SWAT model,run SWAT model.Using SWAT-CUP tool to calibrate and verify the parameters,select the actual runoff data model for 2010-2013 to correct the model,and the result of simulation after correction R~2is 0.892 and Ens is 0.8886;Select 2014 actual runoff data to verify the model,the result R~2is 0.908,Ens is 0.899,the accuracy can meet the model operation,and the SWAT model has good applicability in Qingshui River basin of Chongli area.(3)From 2008 to 2015,the land use of Qingshuihe River Basin in Chongli area changed,and the annual runoff change trend was the same,but the runoff size was different.The results show that the annual runoff of Qingshui River basin in Chongli area has been decreasing since 2008.By using extreme land use analysis method,four different land use scenarios were established to analyze the effects of area changes of different land use types on runoff of watershed.The results showed that the annual runoff change curves under different land use scenarios were similar.But the size of the runoff In the difference,annual average runoff S3 increased by 187.20 m~3/h,S4 decreased by 16.92 m~3/h,S2decreased 33.12 m~3/h,S1 decreased 50.40 m~3/h.results showed that the cultivated land would increase runoff,while woodland,grassland would reduce runoff,and the reduction of woodland was more obvious.(4)According to different land use scenarios,the multi-objective function is established to calculate the influence coefficient of land use type on runoff of river basin.The effect coefficient of cultivated land was 3.168 m3/km2·h,which indicated that cultivated land promoted the runoff,the area increased,and the runoff increased,the influence coefficient of forest land was-1.908 m3/km2·h,and the influence coefficient of grassland was-1.836 m~3/km~2·h,which indicated that woodland and grassland had inhibitory effect on runoff.The area increased and the runoff decreased,and the role of forest land was greater than that of grassland.