Analytical and Laboratory Investigation of Groundwater Pumping in Strip Island Aquifers With Single‐Sided Land Reclamation

Abstract

Abstract Land reclamation has been widely implemented on oceanic islands to alleviate land scarcity. Previous studies of groundwater pumping in reclaimed island aquifers have primarily considered symmetric reclamation and fixed well placement. Here, we extend this framework to an asymmetric strip island aquifer with single‐sided low‐permeability reclamation and variable well placement. We derive analytical solutions for the critical pumping rate, at which the seawater upconing interface just reaches the well bottom, and for the remaining freshwater storage under critical pumping (“residual freshwater storage”). The analytical solutions are validated against laboratory sand‐tank experiments and variable‐density numerical simulations, showing consistent agreement. Sensitivity analyses reveal that low‐permeability reclamation does not universally enhance the critical pumping rate. Instead, the effects of reclamation width and hydraulic conductivity depend strongly on well location, such that a wider and less permeable land reclamation zone may either increase or decrease the critical pumping rate. This non‐monotonic behavior can be mechanistically interpreted by the reclamation‐induced migration of groundwater divides and associated changes in capture zones. In this single‐sided reclamation setting, the optimal pumping location generally does not coincide with the pre‐pumping groundwater divide, contrasting the behavior of homogeneous, symmetric island aquifers. Low‐permeability reclamation increases pre‐pumping freshwater storage, but residual storage under critical pumping may be either greater or smaller than that of a homogeneous island aquifer, highlighting that enhancing freshwater storage and maximizing critical pumping capacity are not equivalent objectives. These results provide a mechanistic framework for evaluating reclamation design, pumping limits and well placement in reclaimed island aquifers.