Finite Land Reclamation at Coastal Region: Impact of Heterogeneity on Groundwater and Seawater Extent

Land reclamation provides available land for various purposes of development at coastal region. The filled sediments having different permeability with original land leads to the heterogeneity effects on groundwater regimes including groundwater head, seawater extent and so on, which were evaluated by several studies that unanimously adopt cross-section to represent entire aquifer (i.e., 2-D reclamation model). This study develops analytical solution for the response of groundwater system to size-limited land reclamation, investigating the permeability effects of reclaimed land. Laboratory experiment and numerical modelling were performed for the verification of derived solution and underlying assumptions, involving situations that hydraulic conductivity of created area is lower, same or higher than/with that of original land. Application of analytical solution in an illustrative aquifer found that the heterogeneous finite land reclamation induces less groundwater level rise than 2-D model, especially for inland constant-flux boundary condition, which would be attributed to the along-shore movement of flow. Moreover, less permeable filling material significantly reduces the flux and extends the travel time of groundwater within reclaimed land, invalidating its benefits of alleviating seawater intrusion from decreasing permeability. The analytical solution presented provides a suitable tool for preliminary prediction of changes to seawater extent and flow distribution caused by finite land reclamation.