Optimum Design Of Groundwater Level Monitoring Network Of Yinchuan Plain

Groundwater is a precious natural resource, due to the development of our society,plenty of groundwater has been exploited and the decline of groundwater level and a series of environmental problems have been caused. Monitoring the space and time variation of the groundwater is an important task of the groundwater management, exploiting, forecast and controlling. In order to study time and space variation of groundwater resource in quality and quantity and provide the ground water government scheme promptly, setting a series of monitoring wells with a purpose in water bearing media, the organic combination of these wells will form groundwater monitoring network.In order to optimize the design of groundwater level monitoring network of Yinchuan Plain.This paper analyzes the available information and our predecessors'research, studys the hydrogeological conditions of Yinchuan Plain systematicly, arranges the characteristics of groundwater system in study area and the data about the distribution and water level of observation wells and finally optimizes the design of groundwater level monitoring network of Yinchuan Plain according to these.Main research contents and conclusions of the paper are as follows:(1) Through the analysis of meteorology,the ground water hyrogeological conditions and so on in Yinchuan Plain,we attribute the factors that affect the danamic viriation of phreatic water to the rainfall infiltration coefficient, land use, topography and landforms, permeability, depth of water table, lithology in unsaturated zone,then draw the zoning map of all factors.(2) Overly the districts of all factors applying ArcGis software,and then re-partition, finally draw a danamic zoning map of groundwater that multiple all factors.The observation wells will be re-laid according to the danamic zoning map in accordance with certain principles.(3) Calculate the expressionγ(h)= 6.4274+0.1247h1.96 for the experimental variogram function in Yinchuan Plain through formula editor in Excel and Visual Fortran programming language according to the water level dataes of observation wells,the character of variogram function and our predecessors'research.(4) Calculate the interpolation error before and after optimization respectively using Kriging interpolation according to the calculation of experimental variogram function and the optimal results of monitoring wells for groundwater level taking use of dynamic partition method in Yinchuan plain, and draw standard deviation contour map and analyze the distribution of errors. We can see that before optimization there is much difference, while after optimization, errors significantly reduce, and vary slightly in the whole Plain, the standard deviation of the interpolation error after optimization is in the range of 0.08-0.53.(5) Compare and analyze the results of before and after optimization,we can see that this optimization result is reasonable through the dynamic partitioning method, the variance threshold value for the interpolation error is not clearly defined, but it can be set according to the manpower, funding, groundwater information accuracy needed during the implementation process of the layout of monitoring wells, reduce the number of observation wells where the variance is smaller than the threshold value, and increase the number of observation wells where the variance is larger than the threshold value, until that meets the required date.