New discovery could provide sustainable freshwater to volcanic islands. Researchers have discovered that twice as much freshwater is stored offshore of Hawaii Island than was previously realized. The experts mapped an extensive reservoir of freshwater within the Hualālai aquifer.
The research has uncovered a new way that substantial volumes of freshwater are transported from onshore to offshore submarine aquifers along the coast of the island. This system may provide alternative renewable resources of freshwater to volcanic islands worldwide.
Study co-author Dean Brian Taylor is an expert in marine geology and geophysics at the UH Mānoa School of Ocean and Earth Science and Technology (SOEST).
“Their evidence for separate freshwater lenses, stacked one above the other, near the Kona coast of Hawai’i, profoundly improves the prospects for sustainable development on volcanic islands,” said Taylor.
The study revealed that freshwater moves from onshore to offshore through a multilayer formation of basalts embedded between layers of ash and soil. The marine geophysics campaign was led by Eric Attias as part of a larger National Science Foundation-funded project.
“Our findings provide a paradigm shift from the conventional hydrologic conceptual models that have been vastly used by multiple studies and water organizations in Hawai’i and other volcanic islands to calculate sustainable yields and aquifer storage for the past 30 years,” said Attias. “We hope that our discovery will enhance future hydrologic models, and consequently, the availability of clean freshwater in volcanic islands.”
“I have spent my entire career developing marine electromagnetic methods such as the one used here, is really gratifying to see the equipment being used for such an impactful and important application. Electrical methods have long been used to study groundwater on land, and so it makes sense to extend the application offshore,” explained study co-author Professor Steven Constable.
Kerry Key is an associate professor at Columbia University who uses electromagnetic methods to image various oceanic Earth structures.
“This new electromagnetic technique is a game changing tool for cost-effective reconnaissance surveys to identify regions containing freshwater aquifers, prior to more expensive drilling efforts to directly sample the pore waters. It can also be used to map the lateral extent of any aquifers already identified in isolated boreholes.”
Study co-author Donald Thomas said the findings confirm two-times the presence of much larger quantities of stored groundwater than previously thought. “Understanding this new mechanism for groundwater is important to better manage groundwater resources in Hawaii.”
The study is published in the journal Science Advances.