Assessment of Land Subsidence based on Geological Conditions, Groundwater Levels in the Choshui River Alluvial Fan, Taiwan

Abstract

        Due to climate change, Taiwan's rainfall has become unstable in recent years, leading to short rainy seasons and low rainfall. In 2021, a severe drought occurred due to the lowest rainfall on record. Groundwater is essential for agricultural development, but less than 10% of wells are legal. Improper or excessive use of groundwater resources can cause serious disasters, such as sea intrusion and land subsidence. However, if the government and farmers extract groundwater effectively and sustainably, it will bring more flexibility to water management.        In this study, a land subsidence model was conducted based on geological conditions and groundwater level. This study analyzes multi layer compaction monitoring well profiles, and further finds the correlation among the two main factors and subsidence. The goal of this study is to visualize which areas are more suitable for using groundwater and assist the government in water resource management. This study focuses on the Choshui river alluvial fan in Taiwan. A risk map of land subsidence for this area is made by evaluating two main factors, geological conditions and groundwater level.