Filter Total Items: 194
Identifying the relative importance of water-budget information needed to quantify how land-cover change affects recharge, Hawaiian Islands
This report describes a sensitivity analysis of a water-budget model that was completed to identify the most important types of hydrologic information needed to reduce the uncertainty of model recharge estimates. The sensitivity of model recharge estimates for the Hawaiian Islands of Oʻahu and Maui was analyzed for seven model parameters potentially affected by land-cover changes within a watershe
Authors
Adam G. Johnson, Alan Mair, Delwyn S. Oki
Availability of groundwater from the volcanic aquifers of the Hawaiian Islands
The islands of Hawaiʻi were built by basaltic shield volcanoes in the Pacific Ocean. These volcanoes formed aquifers that supply hundreds of millions of gallons of fresh water per day to the islands’ residents and diverse industries. Groundwater discharge from the volcanic aquifers to streams and the coast also supports traditional practices and ecosystems. The aquifers' capacity to yield fresh gr
Authors
Scot K. Izuka, Kolja Rotzoll
Magnitude and frequency of floods on Kauaʻi, Oʻahu, Molokaʻi, Maui, and Hawaiʻi, State of Hawaiʻi, based on data through water year 2020
Accurate estimates of flood magnitude and frequency are needed to (1) optimize the design and location of infrastructure, including dams, culverts, bridges, industrial buildings, and highways, and (2) inform flood-zoning and flood-insurance studies. The U.S. Geological Survey (USGS), in cooperation with the State of Hawaiʻi Department of Transportation, estimated flood magnitudes for the 50-, 20-,
Authors
Jackson N. Mitchell, Daniel M. Wagner, Andrea G. Veilleux
Volcanic aquifers of Hawaiʻi—Contributions to assessing groundwater availability on Kauaʻi, Oʻahu, and Maui
The volcanic aquifers of the Hawaiian Islands supply water to 1.46 million residents, diverse industries, and a large component of the U.S. military in the Pacific. Groundwater also supplies fresh water that supports ecosystems in streams and near the coast. Hawaii’s aquifers are remarkably productive given their small size, but the capacity of the islands to store fresh groundwater is limited bec
Authors
Scot K. Izuka, Kolja Rotzoll
Assessment and guidance for using Laser In-situ Scattering and Transmissometry– Stream-Lined 2 (LISST-SL2)
The Laser In-situ Scattering and Transmissometry–Stream-Lined 2 (LISST-SL2) is a second-generation isokinetic river sediment monitoring device that uses laser diffraction to measure suspended-sediment concentration and particle size between 1 and 500 microns in 36 log-spaced bins at a point in a river every second. We compare this latest laser diffraction instrument for suspended-sediment sampling
Authors
Muneer Ahammad, Jonathan A. Czuba, Christopher A. Curran
Groundwater-level monitoring from January 17 to March 3, 2022, Hālawa area, O‘ahu, Hawai‘i
A reported fuel release in November 2021 at the Red Hill Bulk Fuel Storage Facility within the naval reservation at Red Hill led to the shutdown of several production wells in the Hālawa area, O‘ahu, Hawai‘i. Red Hill Shaft—one of the high-capacity production wells that shut down—was reactivated on January 29, 2022. Submersible pressure transducers were deployed at 20 wells in the Hālawa area to m
Authors
Rylen K. Nakama, Jackson N. Mitchell, Delwyn S. Oki
Long-term groundwater availability in the Waihe‘e, ‘Īao, and Waikapū aquifer systems, Maui, Hawai‘i
Groundwater levels have declined since the 1940s in the Wailuku area of central Maui, Hawai‘i, on the eastern flank of West Maui volcano, mainly in response to increased groundwater withdrawals. Available data since the 1980s also indicate a thinning of the freshwater lens and an increase in chloride concentrations of pumped water from production wells. These trends, combined with projected increa
Authors
Kolja Rotzoll, Delwyn S. Oki, Adam G. Johnson, William R. Souza
Water-budget accounting for tropical regions model (WATRMod) documentation
Regional groundwater recharge commonly is estimated using a threshold-type water-budget approach in which groundwater recharge is assumed to occur when water in the plant-root zone exceeds the soil’s moisture storage capacity. A water budget of the plant-soil system accounts for water inputs (rainfall, fog interception, irrigation, septic-system leachate, and other inputs), water outputs (runoff,
Authors
Delwyn S. Oki
January 18, 2022, Red Hill synoptic groundwater-level survey, Hālawa area, O‘ahu, Hawai‘i
On January 18, 2022, groundwater levels were measured in selected wells in the Hālawa area, O‘ahu, Hawai‘i, constituting a synoptic groundwater-level survey (shortened herein to “synoptic survey”) of the area. Groundwater levels were measured mainly from 9:00 a.m. to 12:00 p.m. (times listed in Hawai‘i standard time) and provide a snapshot of groundwater levels during the survey period. Following
Authors
Rylen K. Nakama, Jackson N. Mitchell, Delwyn S. Oki
December 23, 2021, Red Hill synoptic groundwater-level survey, Hālawa area, O‘ahu, Hawai‘i
On December 23, 2021, groundwater levels were measured in selected wells in the Hālawa area, O‘ahu, Hawai‘i, constituting a synoptic groundwater-level survey (shortened herein to “synoptic survey”) of the area. Groundwater levels were measured mainly from 9:00 a.m. to 12:00 p.m. (times listed in Hawai‘i standard time) and provide a snapshot of groundwater levels during the survey period. Following
Authors
Rylen K. Nakama, Jackson N. Mitchell, Delwyn S. Oki
The Hawai'i groundwater recharge tool
This article discusses the design and implementation of the Hawai’i Groundwater
Recharge Tool, an application for providing data and analyses of the impacts
of land-cover modifications and changes in precipitation on groundwater-recharge
rates for the island of O’ahu. This application uses simulation data based on a set of
29 land-cover types and 2 precipitation conditions to provide users with re
Authors
Jared H. McLean, Sean B. Cleveland, Kolja Rotzoll, Scot K. Izuka, Jason Leigh, Gwen A. Jacobs, Ryan Theriot
Groundwater conditions and trends, 2009–19, Saipan, Commonwealth of the Northern Mariana Islands
Groundwater is the primary source of municipal water for Saipan. Nearly all groundwater for the municipal water supply is withdrawn from a freshwater-lens system with a limited amount of freshwater that is susceptible to saltwater intrusion. The status of Saipan’s groundwater resources has not been thoroughly assessed since 2003. The U.S. Geological Survey—in cooperation with the Office of Grants
Authors
Jackson N. Mitchell, Todd K. Presley, Robert L. Carruth