Ocean-aquifer exchange in a warmer Arctic
Abstract
Cryohydrogeological processes in the Arctic and subarctic are rapidly changing due to accelerated atmospheric warming. Along coastlines, changes in cryohydrogeology (distribution of permafrost and yearly frozen ground distributions) and groundwater-surface water exchange can impact conditions on land and in the ocean. Submarine groundwater discharge to the ocean alters the coastal biogeochemistry, while saltwater intrusion both on the surface and in the subsurface results in salinization of coastal freshwater resources. These coastal high-latitude cryohydrogeological processes and the mechanisms mediating aquifer-ocean exchange are understudied compared to high-latitude terrestrial cryohydrogeological systems. This knowledge gap limits our capacity to predict the fate of coastal and near-coastal marine systems under changing climatic conditions. In this study, we use a state-of-the-art cold-regions simulator that simulates freeze-thaw cycles and surface and subsurface flow to study the atmospheric-marine-groundwater interactions in a changing climate. We evaluate the influence of sea-level rise, changing permafrost temperatures, and geologic setting on coastal aquifer-ocean exchange. In some settings, simulations suggest that increased connectivity and deeper groundwater flow paths due to permafrost thaw will increase delivery of terrestrially based water and solutes to the coastal ocean through groundwater pathways. Simulations of other settings suggest that flow through less permeable sediment and alterations in the hydraulic gradient due to permafrost thaw will decrease aquifer-ocean exchange. Additionally, simulations suggest that sea-level rise and decreased terrestrial heads due to permafrost thaw may increase subsurface saltwater intrusion. Enhanced understanding of changes in groundwater flow and aquifer-ocean connectivity due to permafrost thaw is critical as changes will have profound effects on high-latitude coastal zones, impacting marine and freshwater resources.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMB120...03G
- Keywords:
-
- 0428 Carbon cycling;
- BIOGEOSCIENCES;
- 0470 Nutrients and nutrient cycling;
- BIOGEOSCIENCES;
- 0475 Permafrost;
- cryosphere;
- and high-latitude processes;
- BIOGEOSCIENCES;
- 1823 Frozen ground;
- HYDROLOGY