Investigation and Estimation of Groundwater Level Fluctuation Potential: A Case Study in the Pei-Kang River Basin and Chou-Shui River Basin of the Taiwan Mountainous Region

Featured Application Investigating the spatial and temporal dynamic behavior of groundwater level fluctuation in mountainous areas using the proposed approach can assist in obtaining effective strategies for developing and managing groundwater resources. The analysis of the spatiotemporal characteristics of groundwater level variation is a prerequisite for evaluating groundwater potential or underpinning aquifer sustainability development in hydrogeological engineering practices. This study explores the dominant influencing factors that control groundwater dynamics and develops an estimation of groundwater level fluctuation (GWLF) potential in the complex aquifer systems of mountainous areas. Eight natural environmental factors, including slope, drainage density, land use, lithology, hydraulic conductivity, porosity, groundwater depth, and regolith thickness, have been selected as influencing factors, and the feature scores for different factors associated with GWLF potential were given with the expert scoring method. The weighting coefficients of individual influencing factors for wet/dry seasons were determined using the pseudo-inverse method based on the groundwater level data of 18 well stations observed from 1 November 2011 to 31 October 2019 in Taiwan mountainous areas. The results show that the weighting coefficients of these factors in controlling GWLF potential are variable and affected by seasonal and annual rainfall conditions. Based on the determined weighting coefficients, the spatial distribution of GWLF potential can be effectively produced. Finally, the simulated GWLF potential results were verified by comparing the observed data. The verification result demonstrates that the developed model can predict the spatial GWLF distribution based on the groundwater level data from a few wells.