Spatial Variability Of Streambed Hydraulic Conductivity In Manas River

The permeability coefficient(K_v)of the river bed sediment is the key hydrogeological parameter.The permeability coefficient represents the hydrogeological parameters that are difficult to pass through the porous media.The value of the seepage coefficient will affect the exchange of water.Accurate calculation of the coefficient of river bed permeability can deepen the understanding of the transformation relationship between the river and the groundwater and the way of solute transport.It can also solve a series of hydrogeological problems.The coefficient of permeability of the river bed is variable in space and has variability in time.The distribution characteristics of the sediment in the subsurface flow zone directly affect the size of the seepage system,thus affecting the transformation relationship between the river and the groundwater and the ecological function of the river.In order to achieve the determination of permeability coefficient in different dimensions and anisotropy of Manasi River Basin,the variation characteristics of permeability coefficient of river bed in the study area were studied by statistical method and Pearson correlation coefficient method.(1)spatial variability of permeability coefficient of riverbed sediments along the riverThe measured data of permeability coefficient of riverbed sediment along the river indicate that the coefficient of permeability is between 7.31-24.01m/d and.K.The variation coefficient of.K is 0.4,indicating that the variability of the permeability coefficient of the Manasi River along the river is a moderate variation.The model of Ln K is used to obtain the block gold abutment ratio of vertical permeability coefficient of 14%,indicating that the spatial correlation of variables is stronger.Moreover,the correlation between K and the maximum correlation length is 8.24 Km.The reason for the variation of permeability coefficient is mainly due to non-human factors.The variation of osmotic system is attributed to the particle size,topography,and hydrodynamic conditions of river bed sediments.(2)spatial variability of permeability coefficient of river bed sediments in typical sectionsThe measured data of the permeability coefficient of the typical river bed sediments show that the coefficient of permeability is between 1.20-19.24m/d and.K.The variation coefficient of.K is 31.78,which indicates that the variability of the permeability coefficient of the typical section of the Manasi river is strong variation.The Ln K model of the Ln K is used to obtain the block gold abutment ratio of the vertical permeability coefficient of 3%,indicating that the spatial correlation of the variables is stronger,and the nugget value is larger than zero.It is shown that the continuity of permeability coefficient is poor.Moreover,K has correlation when the maximum correlation length is9.78m,and the variation of permeability coefficient is mainly caused by river flow velocity.(3)spatial variability of permeability coefficient of river bed sediments at different depths of typical sectionsThe permeability coefficient of the riverbed sediment permeability system at 0-20cm reaches the maximum 8.52m/d,while the permeability coefficient at 40-60cm is the smallest.The permeability coefficient is 4.32m/d.,and the measured permeability coefficient of the river bed sediment at different depths of the typical section shows that the coefficient of permeability is between 4.06-10.19m/d and the coefficient of variation of K is 3.30.It is shown that the variability of the permeability coefficient of the river bed at different depths of the typical section is strong variation.The K model of Gauss is used to obtain the vertical coefficient of permeability.The ratio of the block to gold abutment is 0.9%,indicating that the spatial correlation of the variables is stronger.In addition,the correlation between K and 80.71cm is mainly due to the influence of topography,geomorphology,river bed sediment and hydrometeorology.The relationship between particle size heterogeneity coefficient Cu and K is linear negative correlation.There is a positive linear correlation between clay content and K.The experimental results of permeability coefficient of different thickness of riverbed sediments show that the maximum value of 10.19m/d reaches 40cm at different thicknesses,then decreases to4.06m/d,and then the osmotic values of riverbed sediments tend to be stable.(4)anisotropy of permeability coefficient shows that there are great differences in the permeability coefficient at different locations on the riverbed section.The seepage performance of the riverbed edge is weak,and the permeability of the river bed center is strong.The spatial variability is mainly caused by the particle size of the sediment.Meanwhile,it is found that the horizontal permeability coefficient Kh is larger than that of any angle,and the permeability coefficient Ks is larger than the vertical permeability coefficient Kv..(5)on the watershed scale,the Manasi river has good permeability,and the maximum infiltration rate reaches 76.66m/d.The permeability coefficient of the Manasi river reaches the maximum at 8Km in the south of the Hongshan mouth.The south of the Hongshan mouth is 8Km to the red mountain mouth.Because the river is subjected to the role of supporting,the infiltration of the river water to the groundwater is obviously reduced.From the top of alluvial fan to the north of the alluvial fan to the area of the Jiahe reservoir,the infiltration capacity of the river is weakened.The permeability coefficient is 6.76m/d.from the Jiahe reservoir area to the Liu Mao Wan area.The permeability coefficient gradually decreases to 1.20m/d,and the permeability coefficient reaches the minimum value from the Liu Mao Wan area to the Ma Hu area.0.92m/d.