Abstract
High latitude mountain environments are experiencing disproportionately
adverse effects from climate change. The Gulf of Alaska (GoA) region is
an embodiment of this change, particularly concerning a shifting
hydrologic balance. Even so, the magnitude and contribution of fresh
submarine groundwater discharge (fresh SGD) remains virtually unexplored
within the region, though it has gained increasing attention globally
due to its chemical significance and influence on coastal ecosystems.
Here we provide the first regional estimates of fresh SGD to the GoA
using two established water balance approaches. This is an effective way
to distinguish the contribution of terrestrially derived fresh SGD,
rather than the more commonly quantified total SGD which includes
discharge that is driven by marine forces such as sea-level oscillations
and density gradients. We compare the approaches and assess their
capabilities in computing the magnitude of fresh SGD over a large
regional scale. Mean annual fresh SGD flux ranges between 26.5 to 86.8
km3 yr-1 to the GoA, equivalent to 3.5-11.4% of the total freshwater
discharge. Contributions are highest in the Southeastern panhandle and
lowest in the Cook Inlet basin, with the highest area normalized
contribution occurring in the Prince William Sound. Fresh SGD exhibits
high spatial and temporal variability throughout the region. Although
freshwater discharge to the GoA is investigated considerably, the
importance of fresh SGD has, thus far, been overlooked.