Volcanic aquifers of Hawaiʻi—Contributions to assessing groundwater availability on Kauaʻi, Oʻahu, and Maui

Abstract

Geographic names in this report are largely consistent with the U.S. Geological Survey (USGS) Board on Geographic Names (http://geonames.usgs.gov/), including the use of the 'okina (') and kahakō (ˉ) diacritical marks in Hawaiian names. The diacritical marks are not used, however, in anglicized derivations from Hawaiian names (for example, the 'okina appears in the name "Hawai'i" but not in the derivation "Hawaiian"), or where a place name appears without the diacritical marks in an established proper noun or title in a cited reference. Names of geologic formations and features are consistent with the State geologic map by Sherrod and others (2021).Both the entire group of Hawaiian Islands and the largest island in the group are named "Hawai'i." To avoid confusion in this report, the island group is referred to as "Hawai'i" and the largest island is referred to as "Island of Hawai'i." The other islands, including those that are the focus of this report (O'ahu, Maui, and Kaua'i), are simply referred to by their names because there is no potential for confusion with other geographic entities.

Groundwater and surface-water interactions in the He‘eia watershed, O‘ahu, Hawai‘i—Insights from analysis of historical data and numerical groundwater-model simulations

“…The He'eia watershed lies in a part of the Ko'olau Range where dikes have intruded the lava flows of the shield volcano (Stearns and Vaksvik, 1935;Takasaki and Mink, 1985;Walker, 1987). The hydrology of dike-intruded areas can be conceptualized as a system of compartments in which groundwater is impounded in compartments of high-permeability lava flows between the low-permeability dikes; this setting is known as dike-impounded groundwater (Takasaki and Mink, 1985;others 2018, Izuka andRotzoll, 2023) (fig. 3).…”

“…Stated alternatively, any amount of groundwater withdrawal from wells and tunnels will be compensated, in the long term, by an equivalent reduction of natural groundwater discharge to springs, streams, wetlands, or the ocean (assuming recharge remains constant). How far the impact of groundwater withdrawals will spread depends on the withdrawal rates and their locations relative to geologic structures, distribution of hydraulic properties, and sites of natural discharge such as springs, streams, wetlands, and the ocean (Izuka and Rotzoll, 2023).…”