## 3 Analysis of Water-Bearing Characteristics in Water-Rich Region  
### High-Density Resistivity Tomography Method  
Electrical Resistance Tomography (ERT) reflects the resistivity distribution of underground media by the conductivity difference of underground rocks and then studies the relationship between media and resistivity to identify different geological bodies. In the field measurement, all the electrodes are set at a certain interval of the measuring point, and the multi-core cable is connected to the programmable multi-channel electrode converter so that the electrode layout is completed once. During the measurement, the operator controls the action to realize the rapid conversion of the electrode arrangement, polar distance and measuring point and accurately and quickly collect a large amount of data. A large number of measured data can be obtained by completing the apparent resistivity observation of the high-density resistivity method on multiple lines in one or even the same measurement area. The collected data are processed by the corresponding electrical processing software, and the corresponding graphic results are given. When the water content of the measurement position is higher, the water body usually has good conductivity, so the resistivity of the rock layer is significantly smaller than that of the surrounding rock. Due to the existence of fault structure, it affects the change of stratum structure in a small range, and then controls the hydrogeological conditions of a certain range of fault zones. Therefore, the focus of this high-density electrical method detection is to investigate the distribution and range of water-rich areas. Two survey lines were arranged along the east-west and north-south directions of the study area. The length of the survey line 1 was 400 m, and the length of the survey line 2 was 500 m. The data were collected by an arrangement (Wenner device), and the electrode point distance was 5 m. The site layout is shown in Figure 5.  
The high-density electrical data acquisition instrument adopted the DZD-8 multi-functional full-waveform DC electrical instrument. The measured data were calculated by the Swedish software RES2 DINV inversion program. After the corresponding processing module performed distortion point removal and terrain correction, the two-dimensional inversion and mapping were performed. The inversion fitting error RMS was \(\leq\)5%.The process is shown in Figure 6.  
Through testing and inversion, the apparent resistivity profile results of line 1 and line 2 are shown in Figure 7. The terrain of line 1 is undulati  
Figure 5: The survey line layout map of the study area. Figure 6: High-density electrical data inversion flow chart. geomorphic unit, and there is no unified marker stratum. In the area of mileage 20-100 m and elevation 372-355 m, the apparent resistivity of the surface layer is obviously higher. Combined with the geological profile and the geological conditions of the site, the lithology of this section is Quaternary loess and conglomerate, and the thickness is about 10-20 m. There are three closed, isolated low resistivity groups at the mileage of about 110-150 m, 290-320 m, and 330 m. The apparent resistivity values in these areas are low, and the resistivity is between 7.2-10.4 \(\Omega\)-m, which is significantly lower than that on both sides. It is inferred that groundwater is enriched. From the resistivity profile of line 2, it can be seen that the apparent resistivity is generally high above and low below. In the area of 90-440 m mileage and 269-299 m elevation, the apparent resistivity contour is relatively continuous in the transverse direction, and the apparent resistivity value is relatively uniform.