San Joaquin River

Meteorological driving forces of reference evapotranspiration and their trends in California

Science of the Total Environment (Elsevier) | August 13th, 2022

Reference evapotranspiration (ETo) is a variable that helps determine atmospheric pressure on living (reference) grass to release water into the atmosphere. For this purp

Reference evapotranspiration (ETo) is a variable that helps determine atmospheric pressure on living (reference) grass to release water into the atmosphere. For this purpose, four main driving forces: air temperature, air humidity, solar radiation, and wind speed need to be measured over the well-watered reference grass. The relative influence of these driving forces is region and climate-specific, with daily and seasonal variations. A clear understanding of the dynamic interactions of ETo's driving factors can illuminate the water and energy cycles of the earth and assist modelers with more accurate predictions of ETo. In this study, Pearson correlation, mutual information, and random forest feature importance analyses have been used to evaluate the relative importance of meteorological driving forces of ETo in California. To better understand the interrelations of these variables, 1,365,823 daily data samples from 237 standardized weather stations for 36 years have been clustered into homogeneous climatic zones and analyzed. To compensate for the effects of seasonality, feature importance analysis is also conducted on seasonal and monthly clustered data. Moreover, seasonal and annual trends of ETo and its driving factors are investigated for California and homogeneous zones using the Mann-Kendall test. Our findings reveal that for annually clustered data, solar radiation is the most influential driving factor of ETo in California. However, analysis of seasonal and monthly clustered data shows that vapor pressure deficit is the most informative factor during the summer and spring, while solar radiation is more important during the colder seasons. Results of trend analysis don't suggest a consistent monotonic trend for ETo and other variables for different seasons and zones. However, it is shown that agricultural regions with heavy irrigation dependence like the Central Valley are getting warmer and drier, especially during the irrigation season. This can adversely affect the water resources, agriculture industry, and food production of California, and modeling efforts like this can be very informative for future water resources management.

Methodology for Flow and Salinity Estimates in the Sacramento-San Joaquin Delta and Suisun Marsh

California Department of Water Resources (DWR) | June 15th, 2022

This is the 43rd annual progress report of the California Department of Water Resources’ San Francisco Bay-Delta Evaluation Program, which is carried out by the Delta M

This is the 43rd annual progress report of the California Department of Water Resources’ San Francisco Bay-Delta Evaluation Program, which is carried out by the Delta Modeling Section. This report is submitted annually to the State Water Resources Control Board pursuant to its Water Right Decision D-1485, Term 9, which is still active pursuant to its Water Right Decision D-1641, Term 8. This report documents progress in the development and enhancement of computer models for the Delta Modeling Section of the Bay-Delta Office. It also reports the latest findings of studies conducted as part of the program. This report was compiled under the direction of Nicky Sandhu, Program Manager for the Bay-Delta Evaluation Program.

Methodology for Flow and Salinity Estimates in the Sacramento-San Joaquin Delta and Suisun Marsh

California Department of Water Resources (DWR) | June 1st, 2017

This is the 38th annual progress report of the California Department of Water Resources’ San Francisco Bay-Delta Evaluation Program, which is carried out by t

This is the 38th annual progress report of the California Department of Water Resources’ San Francisco Bay-Delta Evaluation Program, which is carried out by the Delta Modeling Section. This report is submitted annually by the section to the State Water Resources Control Board pursuant to its Water Right Decision D-1485, Term 9, which is still active pursuant to its Water Right Decision D-1641, Term 8. This report documents progress in the development and enhancement of computer models for the Delta Modeling Section of the Bay-Delta Office. It also reports the latest findings of studies conducted as part of the program. This report was compiled under the direction of Tara Smith, Program Manager for the Bay-Delta Evaluation Program.

Methodology for Flow and Salinity Estimates in the Sacramento-San Joaquin Delta and Suisun Marsh

California Department of Water Resources (DWR) | December 1st, 2019

Various water resource management actions have been planned to protect and restore salmon populations for a healthy Sacramento-San Joaquin Delta (Delta) ecosystem. Curren

Various water resource management actions have been planned to protect and restore salmon populations for a healthy Sacramento-San Joaquin Delta (Delta) ecosystem. Currently, evaluating the effectiveness of these actions relies on field studies and/or expert opinion. Field studies can be costly and may not provide a comprehensive assessment for a range of applications because of limited study areas, durations, and river conditions. Expert opinion, although valuable, may under- or over-emphasize the importance of certain project components.  To supplement field studies and provide a quantitative assessment tool, the California Department of Water Resources (DWR), in collaboration with the United States Geological Survey (USGS), developed an ecological modeling tool, ECO-PTM. ECO-PTM is an individual-based juvenile salmon migration model that is based on a random-walk particle-tracking method with fish-like behaviors attached to the particles. The behavioral parameters are estimated from acoustic telemetry tag data of juvenile late-fall Chinook salmon (Tag Data) from various field studies (Perry et al. 2018). A stochastic optimization tool, Particle Swarm Optimization, is used to calibrate the swimming behavior parameters. ECO-PTM can simulate juvenile salmonid migration timing, routing, and survival.  This chapter describes ECO-PTM and its behavioral modules, and the model performance and applications to assist water resource management planning, assessment, and decision-making related to juvenile salmonid survival outcomes. 

Methods Used to Update Ecosystem Restoration Maps Using New Digital Elevation Model and Tidal Data

Delta Stewardship Council (Delta Council) | June 29th, 2022

Minerals of California Bulletin No. 113

State of California | February 15th, 1938

Missing the Boat on Freshwater Fish Conservation in California

Conservation Letters (Society for Conservation Biology) | March 30th, 2016

Population growth and increasing water‐use pressures threaten California's freshwater ecosystems and have led many native fishes to the brink of extinction. To guide fi

Population growth and increasing water‐use pressures threaten California's freshwater ecosystems and have led many native fishes to the brink of extinction. To guide fish conservation efforts, we provide the first systematic prioritization of river catchments and identify those that disproportionately contribute to fish taxonomic diversity. Using high‐resolution range maps of exceptional quality, we also assess the representation of fish taxa within the state's protected areas and examine the concordance of high‐priority catchments with existing reserves and among distinct taxonomic groups. Although most of the state's native fishes are found within protected areas, only a small proportion of their ranges are represented. Few high‐priority catchments occur within protected areas, suggesting that fish conservation will require active management and targeted river restoration outside of reserves. These results provide the foundation for systematic freshwater conservation planning in California and for prioritizing where limited resources are allocated for fish recovery and protection.

Modeling Barriers and Levee-Break Effects on Delta-Wide Salinity

Delta Stewardship Council (Delta Council) | February 18th, 2016

Modeling Functional Flows in California’s Rivers

Frontiers in Environmental Science (Frontiers) | March 11th, 2022

Modeling the dynamic penetration depth of post-1950s water in unconfined aquifers using environmental tracers: Central Valley, California

Journal of Hydrology (Elsevier) | December 5th, 2022

The penetration depth of post-1950s recharge (D-1950) in aquifers is a marker that is frequently used to identify groundwater that is susceptible to anthropogenic contami

The penetration depth of post-1950s recharge (D-1950) in aquifers is a marker that is frequently used to identify groundwater that is susceptible to anthropogenic contamination. Here, we compute D-1950 values at wells, interpolate them in space, and project them across time to map the moving front of modern recharge in four dimensions in the Central Valley aquifer system, California, USA. Tracers of groundwater age (tritium, carbon-14, noble gases, sulfur hexafluoride, and chlorofluorocarbons) were collected at 650 wells spatially distributed throughout the Central Valley and were fit to a lumped-parameter model that assumes a logarithmic age-depth profile in the aquifer. For samples where tritium was present (>0.3 tritium units), the model was used to predict D-1950 at wells screened above or across the modern-premodern interface (n = 484). Wells with samples where tritium was absent (≤0.3 tritium units) were used to define the depth beyond which groundwater is completely premodern (n = 166). Predicted D-1950 values were below the depth of screen bottoms for wells where groundwater is completely modern, and above the depth of screen tops for wells where groundwater is completely premodern. The interpolated surface of D-1950 is dynamic, less prone to extreme values, and produces maps with lower interpolation errors due to a higher spatial density of wells than maps based on the depth of premodern groundwater. Between 2005 and 2025, D-1950 is expected to deepen by 11 and 12 m in the northern and southern parts of the Central Valley, respectively. Areas where D-1950 increases rapidly are likely to see increases in nitrate and other anthropogenic contaminants associated with the downward moving front of modern water.