Adam G Johnson
Adam Johnson is a hydrologist with the Pacific Islands Water Science Center in Honolulu, Hawaiʻi.
Science and Products
Model subareas and moisture zones used in a sensitivity analysis of a water-budget model completed in 2022 for the islands of Oahu and Maui, Hawaii
A sensitivity analysis of groundwater-recharge estimates from a water-budget model was completed for the islands of Oahu and Maui, Hawaii (Johnson and others, 2023). Results of the sensitivity analysis were used to quantify the relative importance of selected model parameters to recharge estimates for three moisture zones (dry, mesic, and wet) on Oahu and Maui. These shapefiles contain the boundar
Mean annual water-budget components for Oahu, Hawaii, for future-climate conditions, CMIP5 RCP8.5 2041-70 scenario rainfall and 2010 land cover
This shapefile represents the spatial distribution of mean annual water-budget components, in inches, for the island of Oahu, Hawaii for a projected future-climate condition representative of phase 5 of the Coupled Model Intercomparison Project (CMIP5) Representative Concentration Pathway 8.5 (RCP8.5) 2041-70 scenario climate and 2010 land cover, as described in USGS Professional Paper (PP) 1876 b
Mean annual water-budget components for Guam for historic (1990-2009) and future (2080-2099) climate conditions
This data release contains the shapefiles of mean annual water-budget components for Guam for historic (1990 - 2009) and future (2080 - 2099) climate conditions. Components estimated for the 1990 - 2009 scenario represent an update to the historic (1961 - 2005) components estimated by Johnson (2012), and serve as a historic baseline for the components estimated for the future (2080 - 2099) climate
Summary of dissolved pesticide concentrations in discrete surface-water samples collected on the islands of Kauai and Oahu between November 21, 2016 and April 29, 2017
The purpose of this release is to make available the quality-assured pesticide-concentration results for 32 discrete water samples that were collected on the islands of Kauaʻi and Oʻahu between November 21, 2016 and April 29, 2017. This webpage includes brief descriptions of the sampling sites, the samples collected, streamflow conditions during sampling, sample-collection and filtration methods,
Mean annual water-budget components for the Island of Kauai, Hawaii, for current conditions, 2001-10 rainfall and 2001-10 land cover (version 2.0)
The shapefile associated with this metadata file represents the spatial distribution of mean annual water-budget components, in inches, for the Island of Kauai, Hawaii. The water-budget components in the shapefile were computed by a water-budget model for a scenario representative of current conditions (2001-10 rainfall and 2001-10 land cover), as described in U.S. Geological Survey Scientific Inv
Mean annual water-budget components for the Island of Kauai, Hawaii, for predevelopment conditions, 1978-2007 rainfall and 1870 land cover (version 2.0)
The shapefile associated with this metadata file represents the spatial distribution of mean annual water-budget components, in inches, for the Island of Kauai, Hawaii. The water-budget components in the shapefile were computed by a water-budget model for a scenario representative of predevelopment conditions (1978-2007 rainfall and 1870 land cover), as described in USGS Scientific Investigations
Mean annual water-budget components for the Island of Kauai, Hawaii, for recent conditions, 1978-2007 rainfall and 2010 land cover (version 2.0)
The shapefile associated with this metadata file represents the spatial distribution of mean annual water-budget components, in inches, for the Island of Kauai, Hawaii. The water-budget components in the shapefile were computed by a water-budget model for a scenario representative of recent conditions (1978-2007 rainfall and 2010 land cover), as described in USGS Scientific Investigations Report (
Mean annual water-budget components for the Island of Maui, Hawaii, for current conditions, 2001-10 rainfall and 2001-10 land cover (version 2.0)
The shapefile associated with this metadata file represents the spatial distribution of mean annual water-budget components, in inches, for the Island of Maui, Hawaii. The water-budget components in the shapefile were computed by a water-budget model for a scenario representative of current conditions (2001-10 rainfall and 2001-10 land cover), as described in USGS Scientific Investigations Report
Mean annual water-budget components for the Island of Maui, Hawaii, average climate conditions, 1978-2007 rainfall and 2010 land cover (version 2.0)
This shapefile represents the spatial distribution of mean annual water-budget components, in inches, for the Island of Maui, Hawaii. The water-budget components in the shapefile were computed by a water-budget model for a scenario representative of average climate conditions (1978-2007 rainfall) and 2010 land cover, as described in USGS SIR 2014-5168. The model was developed for estimating ground
Mean annual water-budget components for the Island of Maui, Hawaii, for predevelopment conditions, 1978-2007 rainfall and 1870 land cover (version 2.0)
The shapefile associated with this metadata file represents the spatial distribution of mean annual water-budget components, in inches, for the Island of Maui, Hawaii. The water-budget components in the shapefile were computed by a water-budget model for a scenario representative of predevelopment conditions (1978-2007 rainfall and 1870 land cover), as described in USGS Scientific Investigations R
Filter Total Items: 13
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
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
Source-tracking approach for detecting and identifying sources of wastewater in waters of Hawaiʻi
Elevated concentrations of nutrients and the fecal-indicator bacteria enterococci are occasionally detected in Hawai‘i’s surface waters by the State of Hawai‘i Department of Health Clean Water Branch. Management efforts to improve the water quality of surface waters are complicated by the fact that nutrients and enterococci can originate from several sources, including wastewater, animal waste, an
Authors
Adam G. Johnson
Water resources on Guam—Potential impacts of and adaptive response to climate change
The goals of this joint U.S. Geological Survey, University of Hawaiʻi, University of Guam, University of Texas, and East-West Center study were to (1) provide basic understanding about water resources for U.S. Department of Defense installations on Guam and (2) assess the resulting effect of sea-level rise and a changing climate on freshwater availability, on the basis of historic information, sea
Authors
Stephen B. Gingerich, Adam G. Johnson, Sarah N. Rosa, Mathieu D. Marineau, Scott A. Wright, Lauren E. Hay, Matthew J. Widlansky, John W. Jenson, Corinne I. Wong, Jay L. Banner, Melissa L. Finucane, Victoria W. Keener
Estimated groundwater recharge from a water-budget model incorporating selected climate projections, Island of Maui, Hawai‘i
Demand for freshwater on the Island of Maui is expected to increase by 45 percent between 2015 and 2035. Groundwater availability on Maui is affected by changes in climate and agricultural irrigation. To evaluate the availability of fresh groundwater under projected future climate conditions and changing agricultural irrigation practices, estimates of groundwater recharge are needed. A water-budge
Authors
Alan Mair, Adam G. Johnson, Kolja Rotzoll, Delwyn S. Oki
Volcanic aquifers of Hawai‘i—Hydrogeology, water budgets, and conceptual models
Hawai‘i’s aquifers have limited capacity to store fresh groundwater because each island is small and surrounded by saltwater. Saltwater also underlies much of the fresh groundwater. Fresh groundwater resources are, therefore, particularly vulnerable to human activity, short-term climate cycles, and long-term climate change. Availability of fresh groundwater for human use is constrained by the degr
Authors
Scot K. Izuka, John A. Engott, Kolja Rotzoll, Maoya Bassiouni, Adam G. Johnson, Lisa D. Miller, Alan Mair
Spatially distributed groundwater recharge estimated using a water-budget model for the Island of Maui, Hawai`i, 1978–2007
Demand for freshwater on the Island of Maui is expected to grow. To evaluate the availability of fresh groundwater, estimates of groundwater recharge are needed. A water-budget model with a daily computation interval was developed and used to estimate the spatial distribution of recharge on Maui for average climate conditions (1978–2007 rainfall and 2010 land cover) and for drought conditions (199
Authors
Adam G. Johnson, John A. Engott, Maoya Bassiouni, Kolja Rotzoll
Seawater-flooding events and impact on freshwater lenses of low-lying islands: Controlling factors, basic management and mitigation
An unprecedented set of hydrologic observations was collected after the Dec 2008 seawater-flooding event on Roi-Namur, Kwajalein Atoll, Republic of the Marshall Islands. By two days after the seawater flooding that occurred at the beginning of dry season, the observed salinity of water withdrawn by the island’s main skimming well increased to 100% seawater concentration, but by ten days later alre
Authors
Stephen B. Gingerich, Clifford I. Voss, Adam G. Johnson
Spatially distributed groundwater recharge for 2010 land cover estimated using a water-budget model for the Island of O‘ahu, Hawai‘i
Owing mainly to projected population growth, demand for freshwater on the Island of Oʻahu is expected to increase by about 26 percent between 2010 and 2030, according to the City and County of Honolulu. Estimates of groundwater recharge are needed to evaluate the availability of fresh groundwater. For this study, a water-budget model with a daily computation interval was developed and used to esti
Authors
John A. Engott, Adam G. Johnson, Maoya Bassiouni, Scot K. Izuka, Kolja Rotzoll
Water-chemistry data collected in and near Kaloko-Honokohau National Historical Park, Hawaii, 2012–2014
Kaloko-Honokōhau National Historical Park (KAHO) on western Hawaiʻi was established in 1978 to preserve, interpret, and perpetuate traditional Native Hawaiian culture and activities, including the preservation of a variety of culturally and ecologically significant water resources that are vital to this mission. KAHO water bodies provide habitat for 1 threatened, 11 endangered, and 3 candidate thr
Authors
Fred D. Tillman, Delwyn S. Oki, Adam G. Johnson
Investigation of geochemical indicators to evaluate the connection between inland and coastal groundwater systems near Kaloko-Honokōhau National Historical Park, Hawai‘i
Kaloko-Honokōhau National Historical Park (KAHO) is a coastal sanctuary on the western side of the Island of Hawai‘i that was established in 1978 to preserve, interpret, and perpetuate traditional Native Hawaiian culture and activities. KAHO contains a variety of culturally and ecologically significant water resources and water-related habitat for species that have been declared as threatened or e
Authors
Fred D. Tillman, Delwyn S. Oki, Adam G. Johnson, Larry B. Barber, Kimberly R. Beisner
A water-budget model and estimates of groundwater recharge for Guam
On Guam, demand for groundwater tripled from the early 1970s to 2010. The demand for groundwater is anticipated to further increase in the near future because of population growth and a proposed military relocation to Guam. Uncertainty regarding the availability of groundwater resources to support the increased demand has prompted an investigation of groundwater recharge on Guam using the most cur
Authors
Adam G. Johnson
Science and Products
Model subareas and moisture zones used in a sensitivity analysis of a water-budget model completed in 2022 for the islands of Oahu and Maui, Hawaii
A sensitivity analysis of groundwater-recharge estimates from a water-budget model was completed for the islands of Oahu and Maui, Hawaii (Johnson and others, 2023). Results of the sensitivity analysis were used to quantify the relative importance of selected model parameters to recharge estimates for three moisture zones (dry, mesic, and wet) on Oahu and Maui. These shapefiles contain the boundar
Mean annual water-budget components for Oahu, Hawaii, for future-climate conditions, CMIP5 RCP8.5 2041-70 scenario rainfall and 2010 land cover
This shapefile represents the spatial distribution of mean annual water-budget components, in inches, for the island of Oahu, Hawaii for a projected future-climate condition representative of phase 5 of the Coupled Model Intercomparison Project (CMIP5) Representative Concentration Pathway 8.5 (RCP8.5) 2041-70 scenario climate and 2010 land cover, as described in USGS Professional Paper (PP) 1876 b
Mean annual water-budget components for Guam for historic (1990-2009) and future (2080-2099) climate conditions
This data release contains the shapefiles of mean annual water-budget components for Guam for historic (1990 - 2009) and future (2080 - 2099) climate conditions. Components estimated for the 1990 - 2009 scenario represent an update to the historic (1961 - 2005) components estimated by Johnson (2012), and serve as a historic baseline for the components estimated for the future (2080 - 2099) climate
Summary of dissolved pesticide concentrations in discrete surface-water samples collected on the islands of Kauai and Oahu between November 21, 2016 and April 29, 2017
The purpose of this release is to make available the quality-assured pesticide-concentration results for 32 discrete water samples that were collected on the islands of Kauaʻi and Oʻahu between November 21, 2016 and April 29, 2017. This webpage includes brief descriptions of the sampling sites, the samples collected, streamflow conditions during sampling, sample-collection and filtration methods,
Mean annual water-budget components for the Island of Kauai, Hawaii, for current conditions, 2001-10 rainfall and 2001-10 land cover (version 2.0)
The shapefile associated with this metadata file represents the spatial distribution of mean annual water-budget components, in inches, for the Island of Kauai, Hawaii. The water-budget components in the shapefile were computed by a water-budget model for a scenario representative of current conditions (2001-10 rainfall and 2001-10 land cover), as described in U.S. Geological Survey Scientific Inv
Mean annual water-budget components for the Island of Kauai, Hawaii, for predevelopment conditions, 1978-2007 rainfall and 1870 land cover (version 2.0)
The shapefile associated with this metadata file represents the spatial distribution of mean annual water-budget components, in inches, for the Island of Kauai, Hawaii. The water-budget components in the shapefile were computed by a water-budget model for a scenario representative of predevelopment conditions (1978-2007 rainfall and 1870 land cover), as described in USGS Scientific Investigations
Mean annual water-budget components for the Island of Kauai, Hawaii, for recent conditions, 1978-2007 rainfall and 2010 land cover (version 2.0)
The shapefile associated with this metadata file represents the spatial distribution of mean annual water-budget components, in inches, for the Island of Kauai, Hawaii. The water-budget components in the shapefile were computed by a water-budget model for a scenario representative of recent conditions (1978-2007 rainfall and 2010 land cover), as described in USGS Scientific Investigations Report (
Mean annual water-budget components for the Island of Maui, Hawaii, for current conditions, 2001-10 rainfall and 2001-10 land cover (version 2.0)
The shapefile associated with this metadata file represents the spatial distribution of mean annual water-budget components, in inches, for the Island of Maui, Hawaii. The water-budget components in the shapefile were computed by a water-budget model for a scenario representative of current conditions (2001-10 rainfall and 2001-10 land cover), as described in USGS Scientific Investigations Report
Mean annual water-budget components for the Island of Maui, Hawaii, average climate conditions, 1978-2007 rainfall and 2010 land cover (version 2.0)
This shapefile represents the spatial distribution of mean annual water-budget components, in inches, for the Island of Maui, Hawaii. The water-budget components in the shapefile were computed by a water-budget model for a scenario representative of average climate conditions (1978-2007 rainfall) and 2010 land cover, as described in USGS SIR 2014-5168. The model was developed for estimating ground
Mean annual water-budget components for the Island of Maui, Hawaii, for predevelopment conditions, 1978-2007 rainfall and 1870 land cover (version 2.0)
The shapefile associated with this metadata file represents the spatial distribution of mean annual water-budget components, in inches, for the Island of Maui, Hawaii. The water-budget components in the shapefile were computed by a water-budget model for a scenario representative of predevelopment conditions (1978-2007 rainfall and 1870 land cover), as described in USGS Scientific Investigations R
Filter Total Items: 13
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
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
Source-tracking approach for detecting and identifying sources of wastewater in waters of Hawaiʻi
Elevated concentrations of nutrients and the fecal-indicator bacteria enterococci are occasionally detected in Hawai‘i’s surface waters by the State of Hawai‘i Department of Health Clean Water Branch. Management efforts to improve the water quality of surface waters are complicated by the fact that nutrients and enterococci can originate from several sources, including wastewater, animal waste, an
Authors
Adam G. Johnson
Water resources on Guam—Potential impacts of and adaptive response to climate change
The goals of this joint U.S. Geological Survey, University of Hawaiʻi, University of Guam, University of Texas, and East-West Center study were to (1) provide basic understanding about water resources for U.S. Department of Defense installations on Guam and (2) assess the resulting effect of sea-level rise and a changing climate on freshwater availability, on the basis of historic information, sea
Authors
Stephen B. Gingerich, Adam G. Johnson, Sarah N. Rosa, Mathieu D. Marineau, Scott A. Wright, Lauren E. Hay, Matthew J. Widlansky, John W. Jenson, Corinne I. Wong, Jay L. Banner, Melissa L. Finucane, Victoria W. Keener
Estimated groundwater recharge from a water-budget model incorporating selected climate projections, Island of Maui, Hawai‘i
Demand for freshwater on the Island of Maui is expected to increase by 45 percent between 2015 and 2035. Groundwater availability on Maui is affected by changes in climate and agricultural irrigation. To evaluate the availability of fresh groundwater under projected future climate conditions and changing agricultural irrigation practices, estimates of groundwater recharge are needed. A water-budge
Authors
Alan Mair, Adam G. Johnson, Kolja Rotzoll, Delwyn S. Oki
Volcanic aquifers of Hawai‘i—Hydrogeology, water budgets, and conceptual models
Hawai‘i’s aquifers have limited capacity to store fresh groundwater because each island is small and surrounded by saltwater. Saltwater also underlies much of the fresh groundwater. Fresh groundwater resources are, therefore, particularly vulnerable to human activity, short-term climate cycles, and long-term climate change. Availability of fresh groundwater for human use is constrained by the degr
Authors
Scot K. Izuka, John A. Engott, Kolja Rotzoll, Maoya Bassiouni, Adam G. Johnson, Lisa D. Miller, Alan Mair
Spatially distributed groundwater recharge estimated using a water-budget model for the Island of Maui, Hawai`i, 1978–2007
Demand for freshwater on the Island of Maui is expected to grow. To evaluate the availability of fresh groundwater, estimates of groundwater recharge are needed. A water-budget model with a daily computation interval was developed and used to estimate the spatial distribution of recharge on Maui for average climate conditions (1978–2007 rainfall and 2010 land cover) and for drought conditions (199
Authors
Adam G. Johnson, John A. Engott, Maoya Bassiouni, Kolja Rotzoll
Seawater-flooding events and impact on freshwater lenses of low-lying islands: Controlling factors, basic management and mitigation
An unprecedented set of hydrologic observations was collected after the Dec 2008 seawater-flooding event on Roi-Namur, Kwajalein Atoll, Republic of the Marshall Islands. By two days after the seawater flooding that occurred at the beginning of dry season, the observed salinity of water withdrawn by the island’s main skimming well increased to 100% seawater concentration, but by ten days later alre
Authors
Stephen B. Gingerich, Clifford I. Voss, Adam G. Johnson
Spatially distributed groundwater recharge for 2010 land cover estimated using a water-budget model for the Island of O‘ahu, Hawai‘i
Owing mainly to projected population growth, demand for freshwater on the Island of Oʻahu is expected to increase by about 26 percent between 2010 and 2030, according to the City and County of Honolulu. Estimates of groundwater recharge are needed to evaluate the availability of fresh groundwater. For this study, a water-budget model with a daily computation interval was developed and used to esti
Authors
John A. Engott, Adam G. Johnson, Maoya Bassiouni, Scot K. Izuka, Kolja Rotzoll
Water-chemistry data collected in and near Kaloko-Honokohau National Historical Park, Hawaii, 2012–2014
Kaloko-Honokōhau National Historical Park (KAHO) on western Hawaiʻi was established in 1978 to preserve, interpret, and perpetuate traditional Native Hawaiian culture and activities, including the preservation of a variety of culturally and ecologically significant water resources that are vital to this mission. KAHO water bodies provide habitat for 1 threatened, 11 endangered, and 3 candidate thr
Authors
Fred D. Tillman, Delwyn S. Oki, Adam G. Johnson
Investigation of geochemical indicators to evaluate the connection between inland and coastal groundwater systems near Kaloko-Honokōhau National Historical Park, Hawai‘i
Kaloko-Honokōhau National Historical Park (KAHO) is a coastal sanctuary on the western side of the Island of Hawai‘i that was established in 1978 to preserve, interpret, and perpetuate traditional Native Hawaiian culture and activities. KAHO contains a variety of culturally and ecologically significant water resources and water-related habitat for species that have been declared as threatened or e
Authors
Fred D. Tillman, Delwyn S. Oki, Adam G. Johnson, Larry B. Barber, Kimberly R. Beisner
A water-budget model and estimates of groundwater recharge for Guam
On Guam, demand for groundwater tripled from the early 1970s to 2010. The demand for groundwater is anticipated to further increase in the near future because of population growth and a proposed military relocation to Guam. Uncertainty regarding the availability of groundwater resources to support the increased demand has prompted an investigation of groundwater recharge on Guam using the most cur
Authors
Adam G. Johnson