| dc.description.abstract | Coastal groundwater flow are often affected by natural factors, including seasonal groundwater variations, tide and wave fluctuations, or human activities such as agricultural, aquacultural, and industrial water use. This study aims to assess the effects of beach slopes, tidal variations, and hydrogeological conditions on the seawater intrusion and discharge in unconfined aquifers. The hydrogeological data were collected along the westen coastal line of Taiwan. Collected data from DEM, 133 wells, and 10 tide stations show that the average beach slope is less than 20% in western Taiwan. The largest beach slope can reach to 33%. Based on the locations 1 km away from the shoreline, near shore groundwater tables vary in the interval of 0 to 30 m. The average high tide levels are in the range of 0.6 to 2 m and the average low tide level are in the range of 0.2 to 0.08 m. In this study, HYDROGEOCHEM numerical model was used to simulate the interaction of seawater and groundwater in unconfined two-dimensional profile aquifers in western Taiwan. , Simulation results show that the hydraulic conductivity significantly influences the groundwater discharge rate. The increase of inland hydraulic gradient can effectively increase groundwater discharge rate and reduce the density effect. With fixed slope and hydrogeological conditions, 0.5 meter sea level rise can lead to reduction of flow rate about 0.008 m3 / day. When the slope is large (5% to 16%), the chloride ion concentration line (or the saltwater front) in aquifer moves in a short distance. An increase of 0.5 m sea level rise, the saltwater front move landward about 15-20 m. In the low slope(0.5% to 2%) situation, a 0.5 m sea level rise can induce a landward saltwater front movement of 50 to 100 m. Under the condition of extremely steep slope (about 33%), the increase of 0.5 m sea level causes a 5 m seawater front movement. | en_US |