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<\/a>Scientists searching for fresh water hidden beneath the seafloor. (Drone footage credit: Kahiau Cates)<\/p>\nThe goal was to confirm the existence of a potentially massive underground reservoir of fresh or brackish water hidden beneath the seafloor, challenging conventional understanding of island hydrology.<\/p>\n
Peter Kannberg, an associate researcher at the Hawai\u02bbi Institute of Geophysics and Planetology in the University of Hawai\u02bbi at M\u0101noa School of Ocean and Earth Science and Technology, led the survey.<\/p>\n
\u201cIf proven, this deep water could explain longstanding mysteries about Hawai\u02bbi Island\u2019s water cycle\u2014namely, why observed coastal discharge doesn\u2019t match estimated groundwater recharge,\u201d Kannberg said. \u201cIn simple terms, a lot of water is missing from current models.\u201d<\/p>\n
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The roots of this investigation were established when scientists first detected anomalies suggesting a deep, confined aquifer where none should exist in 2018. The theory was that rainwater may be funneled underground and trapped beneath layers of volcanic basalt and ash, extending far beneath the basal freshwater lens and even miles offshore.<\/p>\n
The basal freshwater lens is the layer of fresh groundwater that floats above the denser saltwater.<\/p>\n
\u201cThe traditional model of freshwater on volcanic islands is you got this bathtub of freshwater underneath the island and that bathtub stops right at the shoreline,\u201d Kannberg said. \u201cWhat we\u2019re finding though is that this freshwater extends offshore beyond where the model would predict.\u201d<\/p>\n
If a hidden aquifer is confirmed, the discovery could reshape the understanding of island hydrology and inform future water resource planning, which could help a region increasingly affected by drought and climate change, according to Alex Leonard, senior project manager for Natural Energy Laboratory of Hawai\u2018i Authority<\/p>\n
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\u201cIf a significant fraction of freshwater is escaping through these deep aquifers, then we need to re-calculate how much water can can be withdrawn from the nearshore basal lens for human consumption and how much needs to remain in these shoreline aquifers to provide nutrients to the reefs and nearshore marine environment,\u201d added Don Thomas, Hawai\u02bbi Institute of Geophysics and Planetology faculty who has spent decades studying water and subsurface features across the Hawaiian Islands.<\/p>\n