Assessing Environmental Drivers and Protist Community Dynamics that Shaped the Historic August 2022 Heterosigma akashiwo Bloom in San Francisco Bay, California

Springer Nature | December 22nd, 2025

The Mohave Desert region, California--a geographic, geologic, and hydrologic reconnaissance

U.S. Geological Survey (USGS) | July 15th, 1929

Hydrologic and geologic controls on groundwater recharge along the Mojave River floodplain aquifer

San Diego State University (SDSU) | July 12th, 2016

Groundwater is an extremely important water source for the state of California, particularly in arid regions such as the Mojave Desert. Over-pumping in the Mojave River G

Groundwater is an extremely important water source for the state of California, particularly in arid regions such as the Mojave Desert. Over-pumping in the Mojave River Groundwater Basin has resulted in basin overdraft, and water is imported and artificially recharged to mitigate these effects. Though artificial recharge has helped maintain groundwater-levels, storm flow runoff in the Mojave River is still important and is responsible for more than 80% of natural recharge to the Mojave River floodplain aquifer, the most productive aquifer in the basin. For this reason, it is important to understand processes governing recharge quantity and spatial distribution. The objectives of this study were to determine 1) how total stormflow volume, duration, and peak stormflow control the amount of groundwater recharge at a given distance downstream of where the Mojave River enters the floodplain aquifer, and 2) how geologically-mediated features, including depth to the water table and aquifer and channel morphology, control the amount and spatial distribution of recharge. Univariate and multivariate regressions were run using hydrologic and geologic variables to predict observed water-level rise for ten aquifer segments along the Mojave River, during 6 stormflow events. Results were compared to determine dominant controls on transmission loss and corresponding water-level rise for each segment. Of the two methods used to estimate water-level rise, inverse distance weighting (IDW) results were determined to give a more accurate representation of the system. IDW results indicate that magnitude is the dominant predictor of water-level rise for the entire floodplain aquifer. On a segment basis, recharge to the floodplain aquifer was controlled by different variables going downstream: pre-event water-level (segment 1) near the headwaters, duration (segment 4) and magnitude (segments 5-7) in the middle portion of the river, and peak flow (segments 8-10) towards the outflow of the river. Aquifer and channel variables were statistically significant for 5 out of 6 events. Additionally, a water balance was constructed for the three gaged reaches of the river. By combining reaches 1 & 2, the water budget was balanced with an error within 13% for all but one event. Transmission loss was the largest contributor to groundwater recharge along all three reaches, with artificial recharge and lateral inflow contributing only a very small portion to total observed recharge. Contrary to expectation, the largest water-level rise did not occur in the upstream reaches, where recharge was limited by a combination of channel width, aquifer width, and high pre-event water-levels.

Movement and Age of Ground Water in the Western Part of the Mojave Desert, Southern California, USA

U.S. Geological Survey (USGS) | July 15th, 2004

Tritium and carbon-14 data in water from wells in the Mojave River and the Morongo groundwater basins in the western part of the Mojave Desert show recent recharge focuse

Tritium and carbon-14 data in water from wells in the Mojave River and the Morongo groundwater basins in the western part of the Mojave Desert show recent recharge focused in the floodplain aquifer along the Mojave River. Older ground water was present in parts of the regional aquifer that surround and underlie the floodplain aquifer. Movement of water between the floodplain and the regional aquifers occurs near on the upgradient side of faults as water from the regional aquifer discharges to the floodplain aquifer and on the downgradient side of the faults where water from the floodplain aquifer recharges the regional aquifer. On the basis of carbon-14 ages, corrected for mineralogic reactions with aquifer materials, water from some wells was recharged more than 20,000 years ago. Geochemical data show ground-water recharge has gradually decreased as the climate changed since that time.

Source, distribution, and management of arsenic in water from wells, Eastern San Joaquin Ground-Water Subbasin, California

U.S. Geological Survey (USGS) | October 15th, 2008

Ground-Water Recharge from Small Intermittent Streams in the Western Mojave Desert, California

U.S. Geological Survey (USGS) | July 15th, 2007

Population growth has impacted ground-water resources in the western Mojave Desert, where declining water levels suggest that recharge rates have not kept pace with withd

Population growth has impacted ground-water resources in the western Mojave Desert, where declining water levels suggest that recharge rates have not kept pace with withdrawals. Recharge from the Mojave River, the largest hydrographic feature in the study area, is relatively well characterized. In contrast, recharge from numerous smaller streams that convey runoff from the bounding mountains is poorly characterized. The current study examined four representative streams to assess recharge from these intermittent sources. Hydraulic, thermal, geomorphic, chemical, and isotopic data were used to study recharge processes, from streamflow generation and infiltration to percolation through the unsaturated zone. Ground-water movement away from recharge areas was also assessed.

Chromium, chromium isotopes and selected trace elements, western Mojave Desert, USA

Elsevier | February 6th, 2008

The purpose of this study was to evaluate the geologic, hydrologic and geochemical processes that control natural Cr concentrations and Cr isotopic compositions in ground

The purpose of this study was to evaluate the geologic, hydrologic and geochemical processes that control natural Cr concentrations and Cr isotopic compositions in ground-water.

Geologic Map of the Area Around the Nebo Annex, Marine Corps Logistics Base, Barstow, California

U.S. Geological Survey (USGS) | July 30th, 1993

This map and report present the results of a new geologic field survey of the area surrounding the Nebo Annex of the Marine Corps Logistics Base, near Barstow, California

This map and report present the results of a new geologic field survey of the area surrounding the Nebo Annex of the Marine Corps Logistics Base, near Barstow, California. The map provides a detailed geologic framework that will assist geotechnical and hydrologic operations at the base. The report describes the geologic materials and structures that are shown on the map and explains their significance in terms of regional geologic history. Certain results of the geologic survey have special practical significance for the Nebo Annex. In particular, we found that the Marine base is traversed by several northwest-trending faults of the Camp Rock-Harper Lake system (faults A-E on the map). Fault C is especially noteworthy because it obstructs the flow of shallow ground water; moreover, it probably has moved during Holocene time and should be considered a potential source of earthquake hazards. The major characteristics of this important group of faults are described more fully near the end of this summary.

What is Ground Water?

U.S. Geological Survey (USGS) | April 30th, 1993

Disparities in urban vegetation degradation and heat exposure during drought periods in U.S. cities

nature Portfolio (Springer Nature) | December 15th, 2025

Policymakers are increasingly recognizing the necessity for the equitable distribution of urban green spaces across sociodemographic groups. Nevertheless, the extant rese

Policymakers are increasingly recognizing the necessity for the equitable distribution of urban green spaces across sociodemographic groups. Nevertheless, the extant research consistently highlights disparities in this allocation, frequently neglecting the critical implications of extreme droughts on vegetation-related inequalities. Leveraging satellite observations in conjunction with census data, we examine the drought-related disparities in urban vegetation degradation (UVD) and the corresponding heat exposure across sociodemographic groups within major U.S. cities. Our findings reveal that marginalized communities experience more severe UVD during droughts, a trend particularly pronounced in Sunbelt U.S. cities, such as those in Southern California and Texas. Additionally, the unequal UVD during drought exacerbates existing inequalities in heat exposure. These results highlight the urgent need for the implementation of targeted policies, including effective water supply management strategies. Such measures could mitigate thermal environmental injustices and promote equitable vegetation distribution under a warming climate.