Delineating Hydraulic Heterogeneity Using Fiber Bragg Grating Multi-Level Well and Hydraulic Tomography – A Case Study in Taiwan

Hydraulic tomography (HT) is an innovative method for characterizing the heterogeneous properties of aquifers. This technique involves sequential pumping/injection tests using a network of wells, with simultaneous measurement of groundwater pressure variations. The resulting pressure data is then transformed into hydraulic heterogeneity using a geostatistical approach. Traditional HT tests utilize wells with screens at a single target depth, limiting pressure data collection to specific depth ranges. In contrast, a multilevel well-monitoring system (MLMS) employs multiple open screens at different depths, separated by packers, to prevent vertical flow connections. This configuration significantly increases the amount of pressure data compared to traditional wells. In this study, we implemented a novel multilevel well system based on fiber Bragg grating (FBG) technology for conducting HT at a contaminated site in Taiwan. A comparative analysis of hydraulic conductivity profiles obtained from HT with FBG MLMS and electrical resistivity was undertaken to validate the effectiveness of the FBG MLMS in HT applications. The results demonstrate the reliability and practicality of using an FBG multilevel well system for hydraulic tomography, highlighting its potential for enhanced data collection in heterogeneous aquifer characterization.