Geoff Cromwell is a geologist at the California Water Science Center in Santa Maria, California
Dr. Cromwell's research explores hydrologic systems processes through the development of three-dimensional geologic and hydrogeologic framework models and integrating those models with groundwater, surface-water, and geophysical data. The scope of his work ranges from basin-scale to national-scale, from areas that are data-poor to areas that are data-rich, with a focus on understanding the geologic and hydrogeologic controls on hydrologic systems.
Professional Experience
Geologist at USGS California Water Science Center, Santa Maria, CA (2016 – Present)
Adjunct Assistant Professor in Geology at Occidental College, Los Angeles, CA (2014 – 2015)
Hydrologist at USGS California Water Science Center, San Diego, CA (2014 – 2015)
Hydrologic Technician–Student Trainee at USGS California Water Science Center, San Diego, CA (2011 – 2014)
Education and Certifications
Ph.D., Earth Sciences, Scripps Institution of Oceanography, University of California San Diego, 2014
M.S., Earth Sciences, Scripps Institution of Oceanography, University of California San Diego, 2010
B.A., Geology, Occidental College, 2008
Science and Products
Yucaipa valley integrated hydrological model
Hydrogeologic characterization of the Yucaipa groundwater subbasin
Simulation of groundwater and surface-water resources of the San Antonio Creek Valley watershed, Santa Barbara County, California
Hydrogeologic characterization of the San Antonio Creek Valley watershed, Santa Barbara County, California
Hydrology of the Yucaipa groundwater subbasin: Characterization and integrated numerical model, San Bernardino and Riverside Counties, California
Geology and hydrogeology of the Yucaipa groundwater subbasin, San Bernardino and Riverside Counties, California
Depth to bedrock based on modeling of gravity data of the eastern part of Edwards Air Force Base, California
Using a GIS to populate 3D geocellular geologic models
Holocene paleointensity of the Island of Hawai'i from glassy volcanics
Santa Barbara and Foothill groundwater basins Geohydrology and optimal water resources management—Developed using density dependent solute transport and optimization models
Against the current— The Mojave River from sink to source: The 2018 Desert Symposium field trip road log
Water-resources and land-surface deformation evaluation studies at Fort Irwin National Training Center, Mojave Desert, California
Non-USGS Publications**
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
Evaluation of Groundwater Resources in the Adelaida Area of San Luis Obispo County, California
San Antonio Creek Water Availability
Yucaipa Subbasin Integrated Hydrologic Model
Hydrogeologic data of the Russian River Watershed, Sonoma and Mendocino Counties, California (ver. 1.1, July 2023)
Data Release of hydrogeologic data from the San Antonio Creek Valley watershed, Santa Barbara County, California, 2015-2019
Select borehole data for Edwards Airforce Base and vicinity, Antelope Valley, CA
Science and Products
- Publications
Yucaipa valley integrated hydrological model
IntroductionThe hydrologic system in the Yucaipa Valley watershed (YVW) was simulated using the coupled Groundwater and Surface-water FLOW model (GSFLOW; Markstrom and others, 2008). This study uses version 2.0 of GSFLOW, which is a combination of the Precipitation-Runoff Modeling System (PRMS; Markstrom and others, 2015), and the Newton-Raphson formulation of the Modular Groundwater-Flow Model (MAuthorsAyman H. Alzraiee, John A. Engott, Geoffrey Cromwell, Linda R. WoolfendenHydrogeologic characterization of the Yucaipa groundwater subbasin
IntroductionWater management in the Santa Ana River watershed in San Bernardino and Riverside Counties in southern California (fig. A1) is complex with various water purveyors navigating geographic, geologic, hydrologic, and political challenges to provide a reliable water supply to stakeholders. As the population has increased throughout southern California, so has the demand for water. The YucaiAuthorsGeoffrey Cromwell, John A. Engott, Ayman H. Alzraiee, Christina Stamos-Pfeiffer, Gregory Mendez, Meghan C. Dick, Sandra BondSimulation of groundwater and surface-water resources of the San Antonio Creek Valley watershed, Santa Barbara County, California
In the San Antonio Creek Valley watershed (SACVW), western Santa Barbara County, California, groundwater is the primary source of water for agricultural irrigation, the town of Los Alamos, and supplemental water to Vandenberg Space Force Base (VSFB). Groundwater pumpage has increased since the 1970s as non-irrigated agricultural land has been converted to irrigated land and as local pumping for muAuthorsLinda R. Woolfenden, John A. Engott, Joshua Larsen, Geoffrey CromwellHydrogeologic characterization of the San Antonio Creek Valley watershed, Santa Barbara County, California
The San Antonio Creek Valley watershed (SACVW) is located in western Santa Barbara County, about 15 miles south of Santa Maria and 55 miles north of Santa Barbara, California. The SACVW is about 135 square miles and encompasses the San Antonio Creek Valley groundwater basin; the SACVW is separated from adjacent groundwater basins by the Casmalia and Solomon Hills to the north, and the Purisima HilAuthorsGeoffrey Cromwell, Donald S. Sweetkind, Jill N. Densmore, John A. Engott, Whitney A. Seymour, Joshua Larsen, Christopher P. Ely, Christina L. Stamos, Claudia C. FauntHydrology of the Yucaipa groundwater subbasin: Characterization and integrated numerical model, San Bernardino and Riverside Counties, California
Executive SummaryWater management in the Santa Ana River watershed in San Bernardino and Riverside Counties in southern California is a complex task with various water purveyors navigating geographic, geologic, hydrologic, and political challenges to provide a reliable water supply to stakeholders. As the population has increased throughout southern California, so has the demand for water. The YucGeology and hydrogeology of the Yucaipa groundwater subbasin, San Bernardino and Riverside Counties, California
The Yucaipa groundwater subbasin (referred to in this report as the Yucaipa subbasin) is located about 75 miles (mi) east of of Los Angeles and about 12 mi southeast of the City of San Bernardino. In the Yucaipa subbasin, as in much of southern California, limited annual rainfall and large water demands can strain existing water supplies; therefore, understanding local surface water and groundwateAuthorsGeoffrey Cromwell, Jonathan C. MattiDepth to bedrock based on modeling of gravity data of the eastern part of Edwards Air Force Base, California
We describe a gravity survey acquired to determine the thickness of basin-fill deposits (depth to bedrock) and to delineate geologic structures that might influence groundwater flow beneath the eastern part of Edwards Air Force Base, California. Inversion of these gravity data combined with geologic map and well information provides an estimate of the thickness of basin-fill deposits (defined hereAuthorsVictoria Langenheim, Andrew Morita, Allen H. Christensen, Geoffrey Cromwell, Christopher P. ElyUsing a GIS to populate 3D geocellular geologic models
No abstract availableAuthorsDonald S. Sweetkind, Geoffrey CromwellHolocene paleointensity of the Island of Hawai'i from glassy volcanics
This study presents new high‐quality paleointensity records and 14C radiocarbon age determinations from the Island of Hawai `i during the Holocene. Previous studies on Hawai `i use experimental methods and statistical selection criteria that may produce inaccurate geomagnetic field strength estimates. Additional high‐quality paleointensity results can be used to evaluate the existing Hawaiian dataAuthorsGeoffrey Cromwell, Frank A. Trusdell, Lisa Tauxe, Hubert Staudigel, Hagai RonSanta Barbara and Foothill groundwater basins Geohydrology and optimal water resources management—Developed using density dependent solute transport and optimization models
Groundwater has been a part of the city of Santa Barbara’s water-supply portfolio since the 1800s; however, since the 1960s, the majority of the city’s water has come from local surface water, and the remainder has come from groundwater, State Water Project, recycled water, increased water conservation, and as needed, seawater desalination. Although groundwater from the Santa Barbara and FoothillAuthorsScott R. Paulinski, Tracy Nishikawa, Geoffrey Cromwell, Scott E. Boyce, Zachary P. StankoAgainst the current— The Mojave River from sink to source: The 2018 Desert Symposium field trip road log
The Mojave River evolved over the past few million years by “fill and spill” from upper basins near its source in the Transverse Ranges to lower basins. Each newly “spilled into” basin in the series? sustained a long-lived lake but gradually filled with Mojave River sediment, leading to spill to a yet lower elevation? basin. The Mojave River currently terminates at Silver Lake, near Baker, CA, butAuthorsDavid M. Miller, R.E. Reynolds, Krishangi D. Groover, David C. Buesch, H. J. Brown, Geoffrey Cromwell, Jill N. Densmore, A.L. Garcia, D. Hughson, J.R. Knott, Jeffrey E. LovichWater-resources and land-surface deformation evaluation studies at Fort Irwin National Training Center, Mojave Desert, California
The U.S. Army Fort Irwin National Training Center (NTC), in the Mojave Desert, obtains all of its potable water supply from three groundwater basins (Irwin, Langford, and Bicycle) within the NTC boundaries (fig. 1; California Department of Water Resources, 2003). Because of increasing water demands at the NTC, the U.S. Geological Survey (USGS), in cooperation with the U.S. Army, completed severalAuthorsJill N. Densmore, Justine E. Dishart, David M. Miller, David C. Buesch, Lyndsay B. Ball, Paul A. Bedrosian, Linda R. Woolfenden, Geoffrey Cromwell, Matthew K. Burgess, Joseph Nawikas, David O'Leary, Adam Kjos, Michelle Sneed, Justin T. BrandtNon-USGS Publications**
Cromwell, G., Tauxe, L., Staudigel, H., Constable, C.G., Koppers, A.A.P., Pedersen, R.-B., 2013, In search of long-term hemispheric asymmetry in the geomagnetic field: Results from high northern latitudes, Geochemistry Geophysics Geosystems, 14, 8, (3234-3249), https://doi.org/10.1002/ggge.20174. Non-USGS Affiliation.Cromwell, G., Constable, C.G., Staudigel, H., Tauxe, L., Gans, P., 2013, Revised and updated paleomagnetic results from Costa Rica, Geochemistry Geophysics Geosystems, 14, 9, (3379-3388), https://doi.org/10.1002/ggge.20199. Non-USGS Affiliation.Cromwell, G., Tauxe, L., Staudigel, H., Ron, H., 2015, Paleointensity estimates from historic and modern Hawaiian lava flows using glassy basalt as a primary source material, Physics of the Earth and Planetary Interiors, 241, (44-56), https://doi.org/10.1016/j.pepi.2014.12.007. Non-USGS Affiliation.Cromwell, G., Tauxe, L., Halldórsson, S.A., 2015, New paleointensity results from rapidly cooled Icelandic lavas: Implications for Arctic geomagnetic field strength, Journal of Geophysical Research, Solid Earth, 120, 5, (2913-2934), https://doi.org/10.1002/2014JB011828. Non-USGS Affiliation.Cai, S., Tauxe, L., and Cromwell, G., 2017, Paleointensity from subaerial basaltic glasses from the Second Hawaii Scientific Drilling Project (HSDP2) core and implications for possible bias in data from lava flow interiors: Journal of Geophysical Research: Solid Earth, 122, https://doi.org/10.1002/2017JB014683. Non-USGS Affiliation.Cromwell, G., Johnson, C.L., Tauxe, L., Constable, C.G., and Jarboe, N.A, 2018, PSV10: A Global Data Set for 0–10 Ma time‐averaged field and paleosecular variation studies, Geochemistry Geophysics Geosystems, 19, 5, (1533-1558), https://doi.org/10.1002/2017GC007318. Non-USGS Affiliation, [C:60, D:90, I:70, W:80].Miles, N.D., Deustua, S.E., Tancredi, G., Schnyder, G., Nesmachnow, S., and Cromwell, G., 2021, Using cosmic rays detected by HST as geophysical markers. I. Detection and characterization of cosmic rays: The Astrophysical Journal, 916 (86), 28 p., https://doi.org/10.3847/1538-4357/abfa9b. Non-USGS Affiliation, [C:10, D:10, I:10, W:10].Cromwell, G., and Zhang, Y., 2021, New paleointensity data from Aniakchak volcano, Alaska, USA; Geochemistry Geophysics Geosystems, 22, e2021GC010032. https://doi.org/10.1029/2021GC010032. Non-USGS Affiliation, [C:100, D:60, I:70, W:70].Cych, B., Tauxe, L., Cromwell, G., Sinton, J., and Koppers, A.A.P., 2023, Changes in non-dipolar field structure over the Plio-Pleistocene: New paleointensity results from Hawai`i compared to global data sets: Journal of Geophysical Research—Solid Earth, 128, 6, https://doi.org/10.1029/2023JB026492. Non-USGS Affiliation.**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
- Science
Evaluation of Groundwater Resources in the Adelaida Area of San Luis Obispo County, California
Stakeholders in San Luis Obispo County are concerned that the increased demand for water use has, and will continue to, affect groundwater levels and availability in the Adelaida area. To address stakeholder concerns, the County of San Luis Obispo Board of Supervisors has asked the USGS to conduct a comprehensive evaluation of groundwater resources of the Adelaida area.San Antonio Creek Water Availability
Located in Santa Barbara County, California, the San Antonio Creek Groundwater Basin is a rural agricultural area that is reliant on local water supplies, predominantly groundwater. Because of the growth of irrigated agriculture in the area, water demands have increased significantly, taxing local groundwater supplies. Groundwater resources are also used to supply local inhabitants, as well as...Yucaipa Subbasin Integrated Hydrologic Model
The USGS is developing a hydrologic model of the Yucaipa Subbasin to aid in evaluating and managing the groundwater resources in the area. The study results will provide a greater understanding of the geohydrology of the subbasin, and aid in the development of a groundwater-monitoring plan, as well as in the evaluation of potential hydrologic effects of future groundwater development and... - Data
Hydrogeologic data of the Russian River Watershed, Sonoma and Mendocino Counties, California (ver. 1.1, July 2023)
This data release contains digital data generated by the U.S. Geological Survey under cooperative agreements with Sonoma County Water Agency and the California State Water Resources Control Board to characterize the three-dimensional hydrogeology and water quality of the Russian River Watershed, located in the northern part of the California Coast Ranges section of the Pacific Border province. ThiData Release of hydrogeologic data from the San Antonio Creek Valley watershed, Santa Barbara County, California, 2015-2019
The San Antonio Creek Valley watershed (SACVW) is located in western Santa Barbara County about 15 miles (mi) south of Santa Maria, California and 55 mi north of Santa Barbara, California. The SACVW, is about 140 square miles and encompasses the San Antonio Creek Valley groundwater basin. Since the late 1800s, groundwater has been the primary source of water for agricultural, military, municipal,Select borehole data for Edwards Airforce Base and vicinity, Antelope Valley, CA
Edwards Air Force Base (EAFB) is located in Kern County, CA, approximately 35 kilometers (km) northeast of Lancaster and 9 km south of California City. The Air Force Research Laboratory (AFRL) is situated on EAFB, approximately 7 km southwest of Boron, CA. Release of contaminants from the AFRL facilities have contaminated local groundwater, which is mostly restricted to fractured granitic bedrock, - News