Analysis Of Runoff And Sediment Process In Huangshui Basin Based On WEP-SED Model

In recent years,the Yellow River Basin has been affected by factors such as climate change and human activities.Poor water and sand fixation capabilities have resulted in intensified soil erosion and water and soil erosion problems.Serious land degradation and ecological environment degradation have also occurred.The Huangshui Basin is the largest tributary on the left bank of the upper reaches of the Yellow River.It is located in the transition zone between the Qinghai-Tibet Plateau and the Loess Plateau.The terrain is high in the northwest and low in the southeast,and the mountains and hills in the territory are staggered.Due to its special topographic features,the Huangshui Basin has serious soil erosion,heterogeneous water and sediment sources,and uneven changes.It is the main sediment-producing area in the Yellow River Basin.The distributed basin hydrological model can effectively simulate the water and sediment processes in the basin.In this study,we selected the WEP-SED water and sediment model as the simulation platform,and proposed an indirect method for determining the proportion of sediment components on slopes,gullies,and rivers without the measured sediment transport components.Simulate the water and sediment process in the Huangshui Basin and conduct attribution analysis to quantitatively reveal the water and sediment evolution law of the Huangshui Basin under the influence of climate change and human activities and perform attribution analysis.It is predicted that the water resources of the Huangshui Basin will change under the changing environment from 2020 to 2050.The main research contents and results of this article are as follows:(1)Analyze the characteristics of changes in water and sediment processes such as historical runoff and sediment transport in Minhe section.(1)The annual runoff of the Minhe section showed an insignificant downward trend since the abrupt change occurred from 1962 to 1965;the annual sediment transport of the Minhe section changed abruptly in 1990.According to the change law of water and sediment,1963 ~ 1990 and 1991 ~ 2018 were set as the base period and the change period respectively.(2)The average runoff of the Minhe section for many years was 1.582 billion m3,showing a not significant decrease trend,and the reduction rate was-64 million m3/10 a.The annual runoff during the change period was 14% lower than the base period.(3)The average annual sediment transport volume of the Minhe section was 121.768 million tons,showing a significant decrease trend,and the reduction rate was-3.913 million tons/10 a.The reduction in sediment transport during the change period was 62% of the base period,and the reduction was 4.4 times the annual runoff reduction.(2)Analyze the characteristics of changes in the meteorological monitoring data such as temperature and precipitation in Huangshui Basin.(1)The annual average temperature of the Huangshui River Basin is 0.74 ?,which has increased significantly over the years.The increasing rate is 0.209?/10 a.The annual average temperature changed abruptly in 1989;during the change period,the average annual temperature increased by 0.58 ? from the reference period.(2)The annual average precipitation in the Huangshui Basin is 528.49 mm,which has not increased significantly over the years,and there have been sudden changes in precipitation many times;the annual precipitation increased by 5.43 mm compared with the reference period during the change period.The number of heavy rain and light rain increased during the change period compared with the reference period,and the number of moderate rain days did not change significantly.(3)The construction of the silt dam began in the Huangshui Basin after 1991,which coincided with the abrupt change in annual sediment transport volume.In 2018,the area of the silt dam increased to 27.58 km2,which accounts for a small area of the Huangshui Basin.(3)The WEP-SED water and sediment model was used as a simulation platform to verify and verify the parameters,and analyze the changes of water and sediment processes in the Huangshui Basin.(1)The WEP-SED water and sediment model can better simulate the process of runoff and sediment transport rate in the Huangshui Basin.Among them,the relative error RE in the runoff simulation results is 3.60%,the NASH efficiency coefficient is 0.73,and R is 0.87;in the simulation results of sediment transport rate,RE is-5.38%,NASH coefficient is 0.57,and R is 0.77.(2)The total evapotranspiration during the change period of Huangshui Basin was 2% lower than the base period;the amount of surface water resources has not decreased significantly for many years,and the amount of surface water resources has decreased by 11% from the base period;the amount of groundwater resources has not declined significantly for many years,and the amount of groundwater resources during the change period is 8% lower than the base period.(3)The slope sediment yield,gully sediment yield,and river sediment yield in the Huangshui Basin have obvious decreasing trends,and the three account for 45%,15%,and 40% of the average annual sediment transport,respectively.During the change period,the decline in slope sediment production,gully sediment production,and river sediment production decreased by 82%,1495%,and 183% from the base period.(4)Attribution analysis of water and sediment process in Huangshui Basin under the influence of temperature,precipitation,land use,silt dam and other factors.(1)The total evapotranspiration in the Huangshui Basin has an increasing trend under the influence of the above four influencing factors.The contribution rates of each factor to the total evapotranspiration are 30.1%,74.6%,-6.4%,and 1.6%.(2)The annual runoff of Minhe Section has a decreasing effect under the influence of four factors,and the contribution rate of each factor to the annual runoff is-20.6%,-4.27%,1.9%,-38.6%.(3)The annual sediment transport volume of Minhe Section has the effect of reducing sediment under the influence of the above factors,and the contribution rate of each influencing factor is-15.4%,-59.0%,1.5%,-27.1%.(5)Predict the amount of water resources in Huangshui Basin in 2050.The amount of surface water resources in the year 2050 is 2.08 billion m3,which is 11% lower than the predicted base period(1986~2005).The amount of groundwater resources is predicted to be 1.109 billion m3,which is 3% lower than the predicted base period.The annual runoff of the Minhe section at the 2050 level year is 1.225 billion m3,which is 18% lower than the predicted base period.