HGS RESEARCH HIGHLIGHT – The coastal aquifer recovery subject to storm surge: Effects of connected heterogeneity, physical barrier and surge frequency
Song, J., Yang, Y., Wu, J., & Wu, J. (2022). The coastal aquifer recovery subject to storm surge: Effects of connected heterogeneity, physical barrier and surge frequency. In Journal of Hydrology (Vol. 610, p. 127835). Elsevier BV. https://doi.org/10.1016/j.jhydrol.2022.127835
“HydroGeoSphere (HGS) is applied to simulate the variably saturated and variable-density flow and solute transport processes for storm surge event in the unconfined coastal aquifer.”
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Looking at this study conducted by Jian Song, Yun Yang, Jianfeng Wu and Jichun Wu, scientists have delved into the intricate impacts of storm surges on coastal aquifers, shedding light on the challenges posed by saltwater intrusion exacerbated by climate change.
This research analyzes the combined effects of connected heterogeneity, physical barriers, and surge frequency on coastal aquifer recovery. Using HydroGeoSphere (HGS), Aquanty’s sophisticated modeling platform known for its ability to simulate coupled surface water-groundwater interactions, the team investigated a series of modeling cases in heterogeneous and equivalent homogeneous aquifers.
The findings reveal that connected heterogeneity intensifies saltwater intrusion, extending its reach and shortening recovery times by creating preferential flow paths. In comparison to equivalent homogeneous aquifers, heterogeneity alleviates the maximum salinized extent and vertical intrusion distance due to accelerated mixing of saltwater with fresh groundwater. Physical barriers, such as subsurface dams and cutoff walls, modulate recovery patterns based on connectivity levels. The study also simulated repetitive storm surge events to examine the effects of surge frequency, revealing that low-connectivity aquifers struggle to flush out residual salt masses, especially under high-frequency surge conditions.
At the core of this investigation lies the integration of HydroGeoSphere (HGS), a sophisticated modeling platform known for its ability to simulate coupled surface water-groundwater interactions with unparalleled accuracy. By understanding the interplay between connected heterogeneity, physical barriers, and surge frequency using HydroGeoSphere, stakeholders can better anticipate and mitigate the impacts of saltwater intrusion on coastal aquifers, safeguarding vital freshwater resources for coastal communities.
Plain Language Summary:
In this study, researchers examined how storm surges affect coastal groundwater, which is crucial for drinking and agriculture. They used a computer model called HydroGeoSphere to understand how factors like soil differences, barriers, and storm frequency influence saltwater intrusion into freshwater. The findings show that areas with more soil connections have more saltwater and recover slower. Also, barriers can delay recovery, especially with frequent storms. Understanding these interactions helps communities protect their freshwater from saltwater intrusion caused by storms.
Abstract:
Storm surge, a worldwide phenomenon triggering the vertical saltwater infiltration, is likely to exacerbate coastal groundwater salinization due to geologic heterogeneity, anthropogenic engineering and climate change. This study analyzed the combined effects of connected heterogeneity, physical barrier and surge frequency on the coastal aquifer recovery. A series of modeling cases were investigated using HydroGeoSphere in the heterogeneous and equivalent homogeneous aquifer. The heterogeneity setting is composed of different connectivity level of hydraulic conductivity field. The simulation results of single storm surge event demonstrate that the connected heterogeneity elevates the salinized extent and reduces the aquifer recovery time due to a number of preferential flow paths. In comparison to the equivalent homogeneous aquifer, heterogeneity alleviates the maximum salinized extent and vertical intrusion distance due to the accelerated mixing of salinized groundwater with fresh groundwater. Physical barrier, classified as subsurface dam and cutoff wall, leading to different groundwater discharge pattern is tailored to investigate the influences of the permanent subsurface engineering on the aquifer recovery. Our results show that the connectivity level controls the salinization pattern subject to physical barrier. Then, the repetitive storm surge events were simulated to investigate the effects of surge frequency. For the low-frequency surge event, the variation of salinized metric is the repetition of the unimodal curve in the single surge event. Nevertheless, for the high-frequency surge event, the residual salt mass cannot be flushed out over the simulation period, especially for the low-connectivity aquifer. Meanwhile, the high-frequency surge event broadens the differences of aquifer recovery process due to physical barrier. These findings have critical implications for coastal groundwater management which is facing the substantial environmental risks of surge-induced vertical saltwater intrusion derived from geologic heterogeneity and climate changes.