Investigating Long-Term Interrelation between Groundwater and Surface Water Using Transfer Entropy

Abstract

The accelerated global development process has further intensified climate change, leading to a continuous rise in global temperatures and an exacerbation of climate change severity. This has resulted in an increased frequency of extreme hydrological events. Taiwan, influenced by complex terrain and uneven rainfall distribution, faces challenges in effectively storing rainfall, with individual rainfall allocations falling below the global average. In situations of insufficient surface water supply, groundwater becomes a crucial water source due to its low cost, resistance to pollution, and convenient accessibility. However, prolonged excessive extraction of groundwater not only causes land subsidence but also poses risks of severe disasters such as seawater intrusion. Taiwan’s groundwater is widely distributed and abundant, especially in some regions with advanced agriculture, where it becomes an indispensable key water resource. However, in the context of climate change, rainfall characteristics are subtly and gradually changing, which in turn has an indirect impact on groundwater resources. This study area is the Choshui River Basin located in central Taiwan. We utilize transfer entropy to analyze time series data from groundwater and surface water resources. Transfer entropy is a statistical masure used to quantify the directional flow of information between systems. This method excels in analyzing complex systems where traditional linear methods might fall short, offering insights into how one system influences or is influenced by another over time. It can be adeptly employed to analyze the long-term interaction mechanisms between groundwater and surface water. It specifically investigates the interrelationships and variations in regional groundwater levels during wet and dry seasons, both temporally and spatially. Through an integrated analysis of methods and relevant results, the study aims to explore the primary factors influencing groundwater variations, comprehend trends in groundwater level changes, and provide crucial information on groundwater characteristics. This study contributes to the optimization of the joint allocation and utilization of surface water and groundwater, and can serve as a reference strategy for the allocation and management of regional groundwater.