2024-12-31 パシフィック・ノースウェスト国立研究所(PNNL)
＜関連情報＞
- https://www.pnnl.gov/publications/earth-system-model-simulates-raised-coastal-groundwater-table-caused-sea-level-rise
- https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2024EF004479
海面上昇が沿岸の地下水位に及ぼす影響-陸-海洋結合スキームを用いた地球システムモデルによるシミュレーション Impacts of Sea-Level Rise on Coastal Groundwater Table Simulated by an Earth System Model With a Land-Ocean Coupling Scheme
Donghui Xu, Gautam Bisht, Dongyu Feng, Zeli Tan, Lingcheng Li, Han Qiu, L. Ruby Leung
Earth’s Future Published: 20 August 2024
DOI:https://doi.org/10.1029/2024EF004479
Abstract
Sea-level rise (SLR) poses a severe threat to the coastal environment through seawater intrusion into freshwater aquifers. The rising groundwater table also exacerbates the risk of pluvial, fluvial, and groundwater flooding in coastal regions. However, current Earth system models (ESMs) commonly ignore the exchanges of water at the land-ocean interface. To address this gap, we developed a novel land-ocean hydrologic coupling scheme in a state-of-the-science ESM, the Energy Exascale Earth System Model version 2 (E3SMv2). The new scheme includes the lateral exchange between seawater and groundwater and the vertical infiltration of seawater driven by the SLR-induced inundation. Simulations were performed with the updated E3SMv2 for the global land-ocean interface to assess the impacts of SLR on coastal groundwater under a high CO2 emission scenario. By the middle of this century, seawater infiltration on the inundated areas will be the dominant component in the land-ocean coupling process, while the lateral subsurface flow exchange will be much smaller. The SLR-induced seawater infiltration will raise the groundwater levels, enhance evapotranspiration, and increase runoff with distinct spatial patterns globally in the future. Although the coupling process is induced by SLR, we found topography and warming temperature have more control on the coupling impacts, probably due to the relatively modest magnitude of SLR during the selected future period. Overall, our study suggests significant groundwater and seawater exchange at the land-ocean interface, which needs to be considered in ESMs.
Key Points
- A novel land-ocean coupling scheme is developed and implemented in Energy Exascale Earth System Model version 2 to evaluate the hydrologic exchange at the land-ocean interface
- The impact of land-ocean coupling on the groundwater table is dominated by seawater infiltration, while lateral exchange is negligible
- Future sea-level rise will induce significant seawater intrusion into the coastal groundwater system
Plain Language Summary
As ocean levels rise, seawater threatens to intrude into coastal freshwater aquifers that millions of people depend on for drinking water and irrigation. While regional studies have examined the impacts of sea-level rise (SLR) on coastal groundwater systems, current Earth system models (ESMs) overlook the exchange of water between ocean and groundwater. Our work addresses this gap by developing a water exchange process between ocean and land components in a state-of-the-science ESM. This coupling scheme includes lateral exchanges between seawater and groundwater, as well as vertical seawater infiltration resulting from oceanic inundation. We used this new coupled model to assess SLR impacts on the global coastal groundwater table under a higher CO2 emission scenario. We found that SLR will raise groundwater levels and intensify the hydrological cycle by midcentury mainly due to increased seawater infiltration. Further, while SLR triggers this increased seawater infiltration, topography and warming temperature play more significant roles in determining its magnitude.
