A Study Of High Precision Inversion Methods Of Hydrogeological Parameters Based On Pumping Test

Model of groundwater flow and solute transport simulation is increasingly significant in the groundwater resources management(protection),water pollution repair,safety assessment for nuclear waste geological storage and geological disaster prevention and control,and so on.How to efficiently extract information from the limited observation data,accurate identification of the actual distribution of aquifer space is worthy of study and discussion.The field pumping test is an effective technology to obtain hydrogeological parameters,by which obtain hydrogeological parameters is equivalent parameters,which Strictly speaking only represents the pumping hole between aperture and observ-ation hole near a small area.Affected by test conditions,funds and other factors,setting multiple sets of pumping test is impractical,and it is difficult to accurately depict the space structure of hydraulic parameters based on the limited test data.In order to solve this problem,geophysical tomography theory applied in hydrogeology by hydrological scholars,which hydraulic chromatography is presented.According to different locations and depth to carry out a series of continuous cross pumping(or injection)test,based on head data for identifying the aquifer heterogeneity.Based on pumping test,this paper discusses the hydraulic chromatography pumping test scheme design in different observation Wells,pumping well spacing,and the size of the pumping rate and the influence of sampling time on the inversion accuracy.When the level of the pumping well spacing is not greater than 2,the inversion precision of aquifer parameters increase with the increase of the horizontal spacing,and when the horizontal spacing greater than 2,the inversion precision of parameter K will no longer be obviously improved with the increase of distance.In this article,the wizard point-regularization method is applied to parameter inversion,that is,By increasing the structure limit or a priori information of estimated parameters inversion parameters,its inversion results are discussed.Studies have shown that the following:(1)Relative to the sparse parameterized method,the wizard points-regularization method using a large number of wizard basic can achieve full fitting head,as well as fitting of permeability coefficient.When the wizard layout 18,access to the head of RMSE value is one of the biggest,the inversion effect is the worst.When the wizard point number is greater than the number of observation data,the RMSE values have declined dramatically.(2)Whether application of Tikhonov regularization,T-SVD regularization and SVD-Assist regularization method to inversion parameters,the inversion results is still affected by the observed data.The initial parameter vector and regularization prior information,the more close to reality,the higher the inversion precision.RMSE value along with the increase of the guide point number decreases first,and then showed a trend of increase.These facts show that the guide point is greater than the number of measured data,the number of parameter inversion accuracy is higher,but not the more the better.In the case of data is the same,compared with the simple partition method of inversion results highly parametric method precision is higher.Fusion of multiple pumping test hydraulic chromatography can more accurate identification of aquifer distribution in space,further proved highly parametric method combined with hydraulic chromatography technology can improve the accuracy of model prediction.