Beyond the Wedge: Impact of Tidal Streams on Salinization of Groundwater in a Coastal Aquifer Stressed by Pumping and Sea-Level Rise
Date
2024-09-27
Journal Title
Journal ISSN
Volume Title
Publisher
Water Resources Research
Abstract
Saltwater intrusion (SWI) is a well-studied phenomenon that threatens the freshwater supplies of coastal communities around the world. The development and advancement of numerical models has led to improved assessment of the risk of salinization. However, these studies often fail to include the impact of surface waters as potential sources of aquifer salinity and how they may impact SWI. Based on field-collected data, we developed a regional, variable-density groundwater model using SEAWAT for east Dover, Delaware. In this location, major users of groundwater from the surficial aquifer are the City of Dover and irrigation for agriculture. Our model includes salinized marshland and tidal streams, along with irrigation and municipal pumping wells. Model scenarios were run for 100 years and included changes in pumping rates and sea-level rise (SLR). We examined how these drivers of SWI affect the extent and location of salinization in the surficial aquifer by evaluating differences in chloride concentration near surface waters and the subsurface freshwater-saltwater interface. We found the presence of the marsh inverts the typical freshwater-saltwater wedge interface and that the edge of the interface did not migrate farther inland. Additionally, we found that tidal streams are the dominant pathways of SWI at our site with salinization from streams being exacerbated by SLR. Our results also show that spatial distribution of pumping affects both the magnitude and extent of salinization, with an increase in concentrated pumping leading to more intensive salinization than a more widely distributed increase of the same total pumping volume.
Key Points
- Presence of a saltmarsh inverts the freshwater-saltwater interface in our study location
- Tidal streams contribute substantially to salinization of inland groundwater
- Concentrated pumping led to more intensive salinization than widespread pumping
Description
This article was originally published in Water Resources Research. The version of record is available at: https://doi.org/10.1029/2023WR035840.
© 2024 The Author(s). This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.
This is an open access article under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Keywords
Citation
Hingst, M. C., Housego, R. M., He, C., Minsley, B. J., Ball, L. B., & Michael, H. A. (2024). Beyond the wedge: Impact of tidal streams on salinization of groundwater in a coastal aquifer stressed by pumping and sea-level rise. Water Resources Research, 60, e2023WR035840. https://doi.org/10.1029/2023WR035840