[A-HW25] Near Surface Investigation and Modeling for Groundwater Resources Assessment and Conservation

[AHW25-02] Evaluating the Potential of Groundwater Reservoirs with the Time-lapse Resistivity Imaging Method

*Ping-Yu Chang¹ (1.National Central University)

Keywords:Groundwater Reservoir, Unconfined aquifer, electrical resistivity method

In the study, we utilized the time-lapse resistivity method for estimating the groundwater levels and the specific yields of for the evaluation of potential groundwater reservoirs. We first converted the inverted resistivity into the normalized water content, and we then estimate the parameters of the Brooks-Corey(BC) model from the vertical profiles of the water content. Lastly, we estimated the groundwater level, the theoretical specific yield, and the specific yield capacity from the BC parameters of different survey site in the study area. By interpolating the parameters, the contour maps of the groundwater levels show that the groundwater flows downstream with a higher hydraulic gradient near the river channel. We conclude that the estimated maximum specific yield capacities are consistent to that derived from the pumping tests in the nearby observation well. And the specific yield capacities are only 3/4 to 2/3 to the theoretical specific yields derived from the difference between the residual and saturated water contents in the BC model. We concluded that the distribution pattern of the specific yields had been subjected to the distribution of natural river sediments in the Minzu basin, since the modern channel was artificially modified. Although we had to make some simple assumptions for the estimations, the results show that the surface resistivity surveys provide reasonable estimations of the hydraulic parameters for a preliminary assessment in an area with few available wells.