Study On The Hydrogeophysical Data Fusion Of Electrical Resistivity Tomography And Hydraulic Tomography

Hydrogeophysics is an interdisciplinary and interdisciplinary fusion of geophysics and hydrogeology.The goal of this discipline is to use geophysical detection methods to effectively respond to the need for detailed characterization of underground heterogeneity structures and hydraulics in the field of hydrogeology as well as the large-scale quantitative calculation of parameters,monitoring of physical and chemical processes of soil and underground aquifers,etc.The critical zone of the earth's surface is a complex,heterogeneous near-surface environment.In this thin layer of rock,soil,water,atmosphere,and organisms have complex interactions that regulate the natural ecological environment and determine the availability of sustaining life resources.The underground spatio-temporal information provided by hydrogeophysics will help to study the coupling model of multi-scale-multi-component-multi-process with key,quantitative transformation from physical information to other related discipline information,this new multi-disciplinary cross system breaks down the traditional geophysical single geological structure interpretation mode,more emphasis on information fusion imaging of multi-source multi-field data.Internationally,hydrogeophysics has been regarded as an indispensable method and technology for the study of the ecological environment of key zones on the earth's surface.Refined characterization of stratigraphic structure is a priori condition and key factor for hydrogeological simulation calculations.Compared with traditional stratigraphic models based on geostatistics,geophysical non-intrusive detection methods can characterize more detailed stratigraphic spatial distribution and Heterogeneous characteristics.This paper aims to further study the effectiveness and uncertainty analysis of the method of resistivity tomography for the detection and identification of heterogeneous underground aquifers.Taking the laboratory sandbox experiment as the research object,the laboratory-scale complex heterogeneous aquifer structure is constructed,and the electrode layout method of the resistivity method is optimized according to the statistical characteristics of the correlation scale of the stratum structure,thereby reducing redundant detection arrangements and data acquisition time.At the same time,in order to overcome the insulating boundary conditions around the sandbox scale,a laboratory-scale improved pole-pole observation array was innovatively proposed,and an equipotential reference boundary at a two-dimensional scale was established with copper wire.The complex stratum structure under different unsaturated states is electrically detected and the interpretation of the observed potential is interpreted.The detection results show that the resistivity tomography can better identify the heterogeneity of the aquifer in this form of observation device,and the corresponding estimation uncertainty is greatly reduced;and the resistivity obtained under different saturation states The model and the theory of formation anisotropy characteristics determined by water content have high similarity and correlation.Unlike traditional geophysical borehole verification,this paper proposes to use the estimated resistivity model results as the verification model.The uncorrelated independent resistivity scan measurement data shows a very good linear correlation,which verifies the successive linear estimation inversion,the validity of the algorithm and the accuracy of the model parameter estimation.Therefore,improved resistivity tomography at the laboratory scale and continuous linear estimation are one of the important and effective and economical detection methods for describing complex heterogeneous aquifers.In traditional hydrogeology,the study of groundwater flow and solute transport in heterogeneous aquifer,the main difficulty is to describe the heterogeneity of permeability coefficient in detail.The results of sand box pumping test and solute transport test show that the heterogeneity of aquifer controls the flow and pollutant transport.The hydraulic tomographic scanning technology is similar to the electrical resistivity tomographic imaging.The spatial distribution law of the permeability coefficient of the heterogeneous aquifer is reconstructed by the data of the water level fluctuation at different depths in the wells at different observation positions during multiple pumping tests.The results of the sandbox test show that with the increase of the water level observation data and the number of pumping tests,the inversion accuracy of the hydraulic tomographic is gradually improved,and the parameters are gradually improved.At the same time,the uncertainty of estimation is also reduced.However,in the actual field hydrogeological survey,multiple pumping,large-scale multi well pumping and multi-depth pressure sensor measurement are very difficult to achieve,and the cost is very high.Therefore,it is necessary to reasonably incorporate geophysical field information into hydrogeological model as prior information or constraint information.In this paper,the method of data fusion of resistivity tomography and hydro geophysical tomography is feasible.By fitting the sample data and conductivity observation in a few hydrogeological wells,a general petrophysical relationship model is obtained.The spatial variability of in-situ constitutive equation is ignored,and the electrical information is transformed into permeability coefficient field.Then,the covariance function of spatial correlation was obtained from the electrical model.Using the transformed permeability coefficient field and covariance function as the prior information of hydraulic tomography,the permeability coefficient estimation field can be obtained through a small amount of water head data correction parameter model,even in the area without observed water level data.The experimental results show that the prior information includes many kinds of information,such as stratum,boundary,variability between layers,and relative size of permeability coefficient and so on.The validity of the fusion method is also verified by theoretical numerical simulation.