The application of EH-4 dual-power electromagnetic system to evaluating the shallow groundwater

Talatan area in Gonghe basin of Qinghai Province is rich in Quaternary unconsolidated rock pore water, characterized by similar aquifer and aquiclude resistivity. Therefore,the common ground electric prospecting results look fuzzy,and it is difficult to pre-cisely determine the groundwater level and the thickness of the aquifer. Using dense frequency and high vertical resolution characteris-tics of the EH-4 dual-power electromagnetic system,the authors made an effective trial above the known well. Based on a comparison with the borehole data,the authors calculated the empirical correction coefficient, then carried out MT "十" shape profile measuring and Bostick 1D inversion and EMAP 2D inversion to profile data in the work area,and checked empirical coefficient of the inversion re-sults. Through synthesizing 1D and 2D inversion results, the authors formed inference geological section to quantitatively identify the buried depth and aquifer thickness of the groundwater, and successfully determined well spacing. The expected water inflow was ob-tained at the designed depth,and the interpretation accuracy of MT method was greatly improved.