Effects of Aquifer Bed Slope and Sea Level on Saltwater Intrusion in Coastal Aquifers

Abstract

The quality of groundwater resources in coastal aquifers is affected by saltwater intrusion. Over-abstraction of groundwater and seawater level rise due to climate change accelerate the intrusion process. This paper investigates the effects of aquifer bed slope and seaside slope on saltwater intrusion. The possible impacts of increasing seawater head due to sea level rise and decreasing groundwater level due to over-pumping and reduction in recharge are also investigated. A numerical model (SEAWAT) is applied to well-known Henry problem to assess the movement of the dispersion zone under different settings of bed and seaside slopes. The results showed that increasing seaside slope increased the intrusion of saltwater by 53.2% and 117% for slopes of 1:1 and 2:1, respectively. Increasing the bed slope toward the land decreased the intrusion length by 2% and 4.8%, respectively. On the other hand, increasing the bed slope toward the seaside increased the intrusion length by 3.6% and 6.4% for bed slopes of 20:1 and 10:1, respectively. The impacts of reducing the groundwater level at the land side and increasing the seawater level at the shoreline by 5% and 10% considering different slopes are studied. The intrusion length increased under both conditions. Unlike Henry problem, the current investigation considers inclined beds and sea boundaries and, hence, provides a better representation of the field conditions.

Prediction of groundwater drawdown using artificial neural networks

“…In this study, the factors affecting groundwater drawdown including extraction values, the transmissivity of aquifer formation, depth to the water table, topography (slope and elevation), location in the watershed, distance from water resources (groundwater recharge), annual precipitation, annual evaporation, and distance from industries and residential centers were used as the inputs of the modeling process (Awasthi et al 2005;Shiri et al 2013;Gong et al 2018;Guevara-Ochoa et al 2018, Pradhan et al 2018Abd-Elhamid et al 2020;Shi et al 2021). Examples of inputs are shown in Table (1).…”

“…Slope affects the hydrogeological conditions in a coatal aquifer (Abd-Elhamid et al 2020). A 10 m digital elevation model (DEM) was generated using 10 meter counter lines within the GIS.…”

“…The aquifer type and conditions, including the hydrodynamic characteristics of an aquifer, determine the natural recharge potential and uctuations of the groundwater level (Rukundo and Dogan 2019;Abd-Elhamid et al 2020;Hereher and Al-Awadhi 2020).…”

Numerical Modeling of Saltwater Intrusion in the Rmel-Oulad Ogbane Coastal Aquifer (Larache, Morocco) in the Climate Change and Sea-Level Rise Context (2040)

“…To better understand the saltwater intrusion process, numerous studies have been undertaken, including laboratory-scale investigations and numerical and analytical modeling studies [17][18][19]. A probabilistic numerical model was built to predict the extent of saltwater intrusion into a coastal phreatic aquifer by Felisa et al [17].…”

“…Fahs et al [18] used the semianalytical solution of the dispersive Henry problem based on the Fourier technique to simulate heterogeneous and anisotropic coastal aquifers, taking into account the effects of the aquifer hydraulic parameters, boundary conditions, pumping and recharge rates, and aquifer depth. The effects of aquifer bed slope and seaside slope on saltwater intrusion were investigated by Abdelhamid et al [19] to examine the movement of the dispersion zone under different settings of bed and seaside slopes, and a numerical model (SEAWAT) was applied to the well-known Henry problem.…”