Impacts of Coastal Shrimp Ponds on Saltwater Intrusion and Submarine Groundwater Discharge

Shrimp aquaculture has expanded rapidly in coastal zones worldwide over the past few decades. Saline water stored in shrimp farm ponds can infiltrate into the underlying aquifer causing groundwater salinization and increased submarine groundwater discharge (SGD) to coastal water. However, little research has assessed salinization resulting from these shrimp ponds. To understand the impacts of shrimp farm irrigation on groundwater salinization and SGD, we numerically simulated a series of aquaculture management scenarios in a two-dimensional conceptual coastal aquifer using a coupled surface-subsurface approach. We characterized sensitivities to pond water salinity, pond water depth, and farm width. Salinization was assessed by three indicators (salinized area, infiltrated salt mass, and recovery rate), and three SGD indicators were evaluated (fresh SGD, saline SGD, and saltwater circulation rate). Our results show that pond water depth is the primary control on the mass of saltwater infiltration while farm width is the primary control for recovery rate. Pond water salinity and depth affect both fresh and saline SGD. We show that aquaculture is a previously unrecognized mechanism of salinization affecting coastal aquifer vulnerability and SGD. A regional graphical information system analysis shows transformation into aquacultural ponds could introduce considerable SGD variability spatially and temporally. These findings will enable coastal managers to better evaluate groundwater vulnerability in regions with expanding onshore aquaculture and demonstrates the impact of aquaculture on coastal groundwater resources and the need for further study to understand the impact of aquaculture across Asia and the globe.

Automated summary

Shrimp aquaculture can lead to groundwater salinization and increased submarine groundwater discharge (SGD), but research on this topic is limited. In this study, a numerical simulation approach was used to assess the impacts of shrimp farm irrigation on groundwater salinization and SGD. The results showed that pond water depth had a primary control on the mass of saltwater infiltration, while farm width had a primary control on recovery rate. Both pond water salinity and depth affected fresh and saline SGD. This study highlights the previously unrecognized mechanism of aquaculture on coastal aquifer vulnerability and SGD, emphasizing the need for further research on the impact of aquaculture on coastal groundwater resources.