Study On Sediment Transport Model In Typical Karst Area Of Guizhou Province

The characteristics of a typical karst area in Guizhou are as follows: the terrain is undulating,the soil is fragile,the degree of rocky desertification is serious(the rock is exposed to a large area),and the sediment transport capacity of runoff is relatively large(the erosion of the slope is an unsaturated and unbalanced sediment transport).The process,that is,the eroded sediment in the process of runoff downflow can be carried down).Its special topography has caused serious soil erosion,which has increased the difficulty of research on runoff and sediment production.Therefore,this paper analyzes the characteristics of runoff and sediment yield in this area based on the SWAT model,and analyzes the hydrological response to land use changes using runoff plot experiments and the SWAT model.Analyze the influencing factors of soil erosion,improve the "Guizhou Province Soil and Water Loss Hazard Classification and Grading Standard",and use the SWAT model to transform the standard from qualitative to quantification.research shows:(1)The Wujiangdu hydrological station,Changba hydrological station and Meitan hydrological combined water system map in the Zunyi section of the Wujiang River Basin are divided into three study areas,the SWAT model of the Zunyi section of the Wujiang River Basin is established,and the SWAT model is evaluated with the Nash efficiency coefficient Ens Adaptability to typical karst landforms in Guizhou Province.The results show that the Ens of the runoff simulation at Wujiangdu,Changba,and Meitan hydrological stations are 0.87,0.91,and 0.93,respectively.It was observed that the degree of soil erosion in the Changba area was more serious,so the sedimentation process in the Changba hydrological station area was simulated,and the Ens was 0.87.The simulation results show that the model has a good simulation effect for the study area,and part of the error comes from the reservoir operation and the soil erosion of the construction land.Estimation of soil erosion in the study area was carried out based on the results of sediment simulation,and the results showed that the erosion degree of the Changba hydrological station area is serious,so it is a key area for soil and water conservation.(2)The results of the hydrological response to land use changes are shown as follows: a)An experimental analysis of a runoff community in Zunyi showed that the effect of forest land on runoff and sediment reduction is far greater than that of cultivated land.b)Through the simulation of four land use scenarios by the SWAT model,it is concluded that the conversion of farmland to forest can effectively reduce the runoff on slopes.c)The effect of conversion of farmland to forest in Changba area is analyzed,and the total amount of sediment is estimated to be reduced by 1.716 million tons,Indicating that returning farmland to forests has played a strong role in reducing sediment.Reduced economic losses and slowed down the rate of soil erosion.(3)This article uses the SWAT model to analyze the influencing factors of soil erosion in the Changba area,perfects the "Guizhou Province Soil and Water Loss Hazard Classification and Grading Standards",and makes the soil erosion and erosion intensity classification standards for karst areas and the erosion intensity classification standards for non-karst areas.And analysis of potential threats of soil erosion.The analysis of the potential threat of soil erosion in Changba area shows that the proportion of slope farmland in this area is most sensitive to soil erosion.The above results show that the SWAT model can better simulate the runoff and sediment simulation in the typical karst area of Guizhou.Based on the SWAT model,the hydrological response of different land use modes in the study area and the effect of returning farmland to forest in Guizhou are analyzed.The measures of returning farmland to forest can effectively improve soil erosion.Based on the project of "Guizhou Province Soil Erosion Hazard Classification and Grading Standards",the SWAT model was used to transform the standards from qualitative to quantitative.