Hydrology Respond Simulation Of Soil And Water Conservation Practice On Basis Of HEC-HMS And CA-Markoy

In the western region of China,soil and water loss is one of the main reasons for the shortage of water resources and the deterioration of ecological environment.It is of great practical significance to study the problem of soil and water loss in western China.Based on the data of precipitation,runoff and sediment,the HEC-HMS model and the CA-Markov model were used to study the ground conditions,soil properties and land use characteristics of Luoyugou Watershed in Tianshui,Gansu Province from 1986 to 2008.The model is used to analyze the hydrological processes and land use of the watershed,and the future land use and its water and sediment effects are simulated,and the effects of different soil and water conservation measures are simulated and evaluated.The main findings are as follows:HEC-HMS model is applicable in Luoyu ditch.In the Loess Plateau,most of the runoff process is a single peak flood,which is better on the simulation of the current time.The simulation results of runoff and sediment are limited by the accuracy and the error is larger.The simulation value is smaller than the measured value.The HEC-HMS model has good simulation accuracy and good application effect in the simulation of the sediment runoff and sediment in the Loessou watershed,which provides the basis for the application of the HEC-HMS model in the Loess Plateau.From 1986 to 2008,the area of farmland in high slope area decreased,and the area of forest land increased,and the proportion of terraced fields accounted for the increase of farmland,and the proportion of sloping land decreased.Based on the cellular automata and the Markov chain,the CA-Markov model established a prediction model of spatial land use change corresponding to the study area.Based on the simulation data of Luoyu ditch 1986 and 2001,Land use situation is simulated,the results are consistent with the measured data,to be added to the new land use situation rate.It is predicted that the land use will be reduced in 2018,the proportion of farmland will be decreased,the proportion of forest land will be increased,and the ability of soil and water conservation will increase,and the runoff growth rate will decrease and the peak value and peak of sediment discharge will be lower than that of 2008.According to the area of farmland,the area of forest and grass measures 30%,50%,70%,90%and 100%of the forest land area,the runoff and sediment yield in the basin was simulated and the water saving and sediment reduction efficiency was evaluated quantitatively.The results show that from the upstream to the downstream configuration of the terraced fields,as far as possible in the lower slope,the middle slope,water and sediment reduction benefits are obvious,terraced farmland accounted for about 70%of the proportion is appropriate,the proportion of forestry and forestry measures 50%70%is appropriate,the location of choice in the higher slope,more steep slope of the basin in the upper reaches of the better.Terraced fields and forest and grass measures,in different slope,different slope to reduce soil erosion,so that th effect of soil and water conservation measures to achieve the best.