Effect Of Water And Soil Conservation Measure On Parameter Of Runoff Producing And Conflux

Because of shortage of water resources and serious soil and water loss in the LoessPlateau, the human activities, including soil and water conservation measurement, make thehydrological cycle change. Watershed yield and concentration parameter is a measure of themost important quantitative indicators of meteorological factors and the underlying surfacecharacteristics and runoff, water conservation measures on watershed yield and concentrationparameter rational allocation of water conservation measures, river basin flood control is ofgreat significance. Considering the fact that water and soil conservation measurement has anobvious hydrological benefit, in this paper, the Tuwei River basion as the research object,based on variational characteristics of runoff and division of flood season, the runoffcoefficient and soil water content at the end of precipitation are chosen as runoff parameterand the instantaneous unit hydrograph parameters and the recession coefficient are chosen asconflux parameter. It explore the variation of runoff-conflux parameter which effect on soiland water conservation measures. The main conclusions are followed:(1)This paper uses six kinds of change-point analysis method to find out thechange-point for1978. It divide1956~1978as the base period and1979~2004as themeasures period.(2) Compared with annual and main flood season runoff coefficient between baselineperiod and measure period, They are both showed decline trend and the fluctuant range offlood season runoff coefficient is bigger than annual runoff coefficient. Annual and floodseason average runoff coefficient of baseline period are bigger than measure period.(3) Comparative analysis of the the base period and the measures of the storm floodrunoff coefficient, it is show that heavy rain flood runoff coefficient of measure period reducein different degree under the similar rain intensity, which decreases by29.38%~76.94%at thesimilar rain intensity.(4) Analyzing the soil infiltration rate during the rainfall, soil infiltration rate of baselineperiod is smaller than measure period under similar cumulative rainfall. It is proved thatvegetation coverage rate and soil condition have been improved which increase the plantinterception and soil infiltration capacity and improve soil and water loss.(5) Similar to the cumulative precipitation conditions, measures of peak flow and floodthan the base period is smaller and peak flow attenuation rate than about70%. The instantaneous unit hydrograph parameters of measure period are bigger than base period.(6) Recession coefficients are compared during the base period and measure period. Theresult shows that groundwater recession coefficients are respectively643and1221during thebase period and measure period. The recession parameter of dry season flow in measureperiod is bigger than baseline period which increase from12.32%to527%under the similarannual precipitation.(7) This paper analyses the original causes of water and soil conservaton effection onrunoff-conflux parameters, which suggest soil and water conservation measures to increasethe basin volume of water, reduce surface runoff. At the same time, this paper uses the set pairanalysis to calculate the connection counts between runoff and water and soil conservationmeasure.The result shows that water and soil conservation measure could reduce thecorrelation between precipitation and runoff.