Numerical modeling of the effects of beach slope on water-table fluctuation in the unconfined aquifer of Donghai Island, ChinaModélisation numérique des effets de pente du rivage sur les fluctuations de la surface d’un aquifère libre, Ile Donghai, ChineModelado numérico de los efectos de la pendiente de la playa sobre la fluctuación del nivel freático en el acuífero no confinado de la Isla Donghai, China潜水水位波动斜坡效应的数值模拟研究—以中国东海岛为例Modelação numérica dos efeitos do declive de praia na flutuação do nível freático do aquífero livre da Ilha de Donghai, China

Beach slope is an important factor influencing the tide-induced water-table fluctuation in coastal unconfined aquifers. However, research about the effect of beach slope on water-table fluctuation is limited, especially for gentle slopes. To understand the effect of beach slope on beach groundwater dynamics, a numerical model, calibrated with field monitoring data from Donghai Island (China), was built to simulate the observed water-table fluctuation. Sensitivity analysis was performed to assess the sensitivity of water-table fluctuation to the parameters and conceptualization of the model. The analysis indicated that the water-table fluctuation was especially sensitive to the hydraulic conductivity and specific yield, and the horizontal length of the model domain could affect the amplitude of the water-table fluctuation. Moreover, it is found that the variation of the amplitude is more evident when the beach-slope angle changes in the range from 1.5 to 45°, especially in the range from 1.5 to 5°. Understanding the effect of beach slope on tide-induced water-table dynamics could help modelers deal with the slope better in their beach groundwater flow models.