Spatial Variability Of Aquifer Hydraulic Conductivity In Arid And Semi-arid Areas In Northwest China

The hydraulic conductivity K of aquifer is one of the most important hydrogeolog ical parameter, which influencing the conversion relationship between river and ground water, the amount of infiltration from river, excretion from aquifer to river and the mi ning capacity of riverside wells. Permeability coefficient represents the ability to transf er water in porous media, accurate estimate riverbed permeability is very important for the analysis of river ecosystems and their relationship in a groundwater basin,while h elping to understand the exchange of water and the extent of Water migration between n river and groundwater, it also may solve a series of problems related to the hydrog eological. In this paper, using traditional statistical methods and geostatistical methods to do a thorough analysis of normality distribution and variability of measured data.Re search findings obtained following aspects:This paper selects hydraulic conductivity in three different scales as the research object,being taken as investigated area,and geostatisticaI approach is appIied to anaIyze the statistic distributions and the spatia I corre Iativity of hydrogeoIogical parameters of unconfined aguifer.。The hydraulic conductivity is considered as a regionalized variable. Then the structure of spatial variation could be established to calculate the theoretical variogram of experimental data for generating the variogram model of spatial directions. After cross validation, ordinary Kriging analysis was provided to expand the spatial variation of hydraulic conductivity and reflect the anisotropic variability in contour map. Results showed that the log of hydraulic conductivity has strongly anisotropic variability and illustrated the minimum variation along the N30°E direction and the maximum variation along the E30°S direction. The anisotropic of topography in such area is controlled by its hydrogeology factor while aquifer was forming..1. Spatial variability of hydraulic conductivity in large scaleThe statistica I distribution of The 57 measured conductivity values of aguifer is is submitted to lognormal distribution.Selection of the lag distance is 297772 m, spacing for 29777 m, under angel limit of 22.5 °, and calculate the number of experimental variogram permeability of the aquifer, and draw graphs of experimental variograms. Description penetration in the range of about 30000 m coefficients associated with each other. The corre Iation distances of the two parameters in N40°E direction are all larger than others.2. Spatial variability of hydraulic conductivity in medium scaleThe statisticaI distribution of The 64 measured conductivity values of aguifer is is submitted to lognormal distribution. Spatial distribution of permeability in the area lognormal distribution.Selection of the lag distance for the next 46920 m, spacing for the 4692 m, angel limit of 22.5 °,and calculate the number of experimental variogram permeability of the aquifer, and draw graphs of experimental variograms. Description penetration in the range of about 4700 m coefficients associated with each other. The corre Iation distances of the two parameters in N60°E direction are all larger than others.3. Spatial variability of hydraulic conductivity in small scaleThe statisticaI distribution of The 35 measured conductivity values of aguifer is is submitted to lognormal distribution and normaI probabiIistic distribution. Spatial distribution of permeability in the area lognormal distribution.Selection of the lag distance for the next 35937 m, spacing for 3593 m, angel limit of 22.5 ° and calculate the number of experimental variogram permeability of the aquifer, and draw graphs of experimental variograms. Description penetration in the range of about 4700 m coefficients associated with each other. The corre Iation distances of the two parameters in N40°E direction are all smaller than others,which is also in line with the point of the distribution and structure of the aquifer.The research in three different scales permeability coefficient involves a lot of experimental studies, and preliminarily elicits the aquifer permeability distribution space, quantitatively studied the spatial variability of the value of K under different scales, in-depth analyzed the factors affecting changes in the value of K, provides a reliable parameter of translational research relationship on Golmud River surface water and groundwater.