| Based on the Ganjiang river basin as the research object,this paper on the basis of the Ganjiang river basin and the adjacent area of 27 meteorological stations from 1961 to 2015,rainfall,the Ganjiang Jian and Xiajiang,Zhangshu,Waizhou in river sediment discharge,watershed hydrological station month 90 MB of space resolution DEM figure,1985-2010,5 stages 100 m spatial resolution land use map,soil map,such as geographic information data,USES the time series analysis method mining time and space distribution law of sediment discharge,segmentation study period(1961-2015)for the modeling period(1961-1982),validation period(1983-1985)and efficiency analysis period(1986-2015).During the modeling period,with the help of ArcGIS software,will study basin grid spatial resolution to 90 m calculation point,USES the universal soil loss equation(USLE)to estimate the grid annual rainfall erosion force factor R,soil corrosion factor K slope factor LS,vegetation coverage,slope factor and management factor C and management measures of soil and water conservation factor P and soil erosion.Based on Matlab software programming,calculate the cumulative confluence time of each computing grid to its recent river channel,and calculate the model parameters and sediment transport ratio of each grid based on the measured value of sediment transport.In the simulation study,the sediment transport quantity of Ganjiangjiang river basin was compared with the measured value of each water station to verify the effect of the model.Comparing the land use and forest coverage data of the basin,the recovery effect of forest vegetation in the study period was analyzed,and the response to the forest vegetation restoration was revealed,and the results showed that:(1)Ganjiang river basin climate instability in years,rainfall concentrated in April and June,more volatile during the other months,uneven rainfall but rainfall in each of the rules,and sediment discharge and rainfall is positive correlation.(2)Based on the linear regression analysis of the measured annual sediment trend chart of the hydrological station of the study area,the slope rate of the study is between-22.43 to-18.557,and the significance level R is greater than R_α,and the decrease trend is obvious.In the basin,there is a variation point of the measurement of the sediment load of the water station in the water station.In 1994-1997,the Cv value of the sediment transport is greater than that of the mutation before the mutation.Land use has not changed much,but forest coverage has continued to rise since 1990.(3)The SEDD model parameters estimated in the modeling period are the Jian stationβ=1.43,Xiajiang stationβ=1.36,Zhangshu stationβ=1.63,Waizhou stationβ=1.64.The modeling and verification period of annual sediment yield simulation value Nash efficiency coefficient(E)and correlation coefficient(R)can be verified:Jian station control station control basin E=0.521,r=0.741;Xiajiang station control basin E=0.527,r=0.768;Zhangshu station control basin E=0.570,r=0.798;Waizhou station control basin E=0.618,r=0.844.According to the results of the verification results are shown better model simulation,can be used for the benefit analysis to simulate the river sediment discharge.(4)Strength close to the modeling period in the reservoir construction under the conditions of sediment discharge forecast,every 10%forest coverage sediment discharge reducing rate is improved by more than 15%,and weakened dramatically with the strength of the reservoir construction,the forest coverage rate of increase of similar average sediment discharge under the condition of lower rate of 7.25%,relatively declined.These data suggest that lower reservoir of sediment discharge has a certain effect,already included in the model prediction effect ability under the condition of similar reservoir,up10%forest coverage in each river sediment discharge to reduce the rate of between 15%and 33%is an important factor to reduce the river sediment discharge. |
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