Using Electrical Resistivity Imaging Method to Estimate the Water Table and the Specific Yield of the Unconfined Aquifer: A Case Study along the Wuxi River in the Taichung-Nantou Basin, Central Taiwan.

• Main Authors: Jordi Mahardika Puntu, 嚴精明
• Other Authors: Prof. Ping-Yu Chang
• Format: Others
• Language: en_US
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/6e3992

碩士 === 國立中央大學 === 地球科學學系 === 107 === The Taichung-Nantou Region is the area with savings of the groundwater, and also with good recharge sources among the groundwater provinces in Taiwan. However, there are only limited observation wells for monitoring the groundwater quantity and quality in the region. In order to provide supplementary measurements for the area, we conducted Electrical Resistivity Imaging (ERI) surveys for time-lapse monitoring of the groundwater level, and also attempt to estimate the hydrogeological parameter. We deployed eleven ERI survey lines with both Wenner and Schlumberger array configurations and conducted the time-lapse measurements 5 times during the year of 2018. Based on the Archie’s Law, we first estimate the relative saturation with the ERI results, then calculate the VG parameters for identifying the water table using the Soil Water Characteristic Curve (SWCC). Lastly, we estimate the theoretical specific yield (Sy) based on the VG model. Our results show that the groundwater level varies between 22.85-m to 51.44-m in the area. In addition, the difference of groundwater level against that measured ones in February is ranging from 1.64-m to 6.52-m. The highest groundwater level took place in July (the wet season) and the lowest groundwater level appears to be in February (the dry season). Moreover, we found that the Sy values are about 0.20-0.26 in the study area, and the lowest Sy value is in the WS02 line.