Hurricanes, heavy rains are critical for Hawai'i's groundwater supply


Date:
October 13, 2020
Source:
University of Hawaii at Manoa
Summary:
New research indicates that rain brought to the islands by
hurricanes and Kona storms can often be the most important
precipitation for re- supplying groundwater in many regions of
the island of O'ahu.



FULL STORY ========================================================================== Located within the most isolated archipelago in the world, Hawai'i
is critically dependent on a clean, ample supply of fresh water. New
research led by University of Hawai'i at M?noa scientists indicates that
rain brought to the islands by hurricanes and Kona storms can often be
the most important precipitation for re-supplying groundwater in many
regions of the island of O'ahu.


==========================================================================
"The majority of Hawai'i's freshwater comes from groundwater," said
Daniel Dores, lead author and groundwater and geothermal researcher in
the UH M?noa School of Ocean and Earth Science and Technology. "In this
study, we investigated the relationship between trade wind showers,
major rainfall events like Kona storms, and groundwater." Dores and
a team of scientists from SOEST and the Hawai'i Department of Health
collected rainfall around the island of Oahu and analyzed the stable
isotopes of rainwater, chemical signatures in the water molecules. They compared the chemical signatures in rainwater to those of groundwater
to determine the source of water in the aquifers -- event-based rainfall
or trade wind-related rain.

"Because windward and mauka showers are so common, it is easy to assume
that is the main source of our drinking water," said Dores. "Also,
large rainfall events such as Kona storms result in significant runoff
into the oceans.

However, our research found that a lot of the rain from Kona storms
makes it into our groundwater aquifers and is an important source of
our drinking water." Hawai'i is experiencing substantial changes in
trade wind weather patterns, and precipitation events could become more extreme. Some of the study co-authors will continue research to understand
more about local and regional groundwater recharge and water quality.

"By better understanding how our groundwater is impacted by these
extreme precipitation events, we can better protect the resource itself,"
said Dores.


========================================================================== Story Source: Materials provided
by University_of_Hawaii_at_Manoa. Original written by Marcie
Grabowski. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Daniel Dores, Craig R. Glenn, Giuseppe Torri, Robert B. Whittier,
Brian
N. Popp. Implications for groundwater recharge from stable isotopic
composition of precipitation in Hawai'i during the 2017-2018
La Nin~a.

Hydrological Processes, 2020; DOI: 10.1002/hyp.13907 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/10/201013111322.htm

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