Geology topics

Research about Central Valley of California

Source-linked reports with geographic coverage including Central Valley of California.

3 recordsLinked to original sources

USGS2021

Using the California Waterfowl Tracker to assess proximity of waterfowl to commercial poultry in the Central Valley of California

Migratory waterfowl are the primary reservoir of avian influenza viruses (AIV) which can be spread to commercial poultry. Surveillance efforts that track the location and abundance of wild waterfowl and link those data to inform assessments of risk and sampling for AIV currently do not exist. To assist surveillance and minimize poultry exposure to AIV, here we explored the utility of remotely sensed MODerate Resolution Imaging Spectroradiometer (MODIS) satellite imagery in combination with land-based climate measurements (e.g., temperature and precipitation) to predict waterfowl location and abundance in near real-time in the California Central Valley (CCV), where both wild waterfowl and domestic poultry are densely located. Specifically, remotely collected MODIS and climate data were integrated into a previously developed Boosted Regression Tree (BRT) model to predict and visualize waterfowl distributions across the CCV. Daily model-based predictions are publicly available during the winter as part of the dynamic California Waterfowl Tracker (CWT) web-app hosted on the University of California’s Cooperative Extension webpage. In this study, we analyzed 52 days of model predictions and produced daily spatio-temporal maps of waterfowl concentrations near the 605 commercial poultry farms in the CCV during January and February of 2019. Exposure of each poultry farm to waterfowl during each day was classified as “high”, “medium”, “low”, or “none” depending on the density of waterfowl within 4 km of a farm. Results indicated that farms were at substantially greater risk of “exposure” in January, when CCV waterfowl populations peak, than in February. For example, during January, 33% (199/605) of the farms were exposed ≥ 1 day to “high” waterfowl density versus 19% (115/605) of the farms in February. In addition to demonstrating the overall variability of waterfowl location and density, these data demonstrate how remote sensing can be used to better triage AIV surveillance and biosecurity efforts via the utilization of a functional web-app based tool. The ability to leverage remote sensing is an integral advancement toward improving AIV surveillance in waterfowl in close proximity to commercial poultry. Expansion of these types of remote sensing methods linked to a user-friendly web-tool could be further developed across the continental U.S. The BRT model incorporated into the CWT reflects a first attempt to give an accurate representation of waterfowl distribution and density relative to commercial poultry.

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USGS2017

Changes in the abundance and distribution of waterfowl wintering in the Central Valley of California, 1973–2000

The Central Valley of California is one of the most important areas for wintering waterfowl in the world and the focus of extensive conservation efforts to mitigate for historical losses and counter continuing stressors to habitats. To guide conservation, we analyzed trends in the abundance and distribution (spatiotemporal abundance patterns) of waterfowl and their habitats in the Central Valley and its major subregions (Sacramento Valley, Suisun Marsh, Delta, San Joaquin Valley), from 1973 through 2000. We used existing databases, satellite imagery, and aerial photography to measure habitat area, and aerial surveys and radio telemetry to track the abundance and distribution of wintering waterfowl. Wetlands increased throughout the Central Valley, but agricultural fields flooded after harvest increased greatly to the north in the Sacramento Valley and decreased to the south in the San Joaquin Valley, resulting in an overall increase in the relative availability of winter habitat in the former region. Reflecting the continental decline of the most abundant wintering species (Northern Pintail, Anas acuta ), the overall abundance of wintering waterfowl in the Central Valley declined during our study. By contrast, numbers of the American Wigeon ( A. americana ), Mallard ( A. platyrhynchos ), and Northern Shoveler ( A. clypeata ) were stable, and numbers of the Green-winged Teal ( A. crecca ), Gadwall ( A. strepera ), diving ducks, and geese increased from 1973–1982 to 1998–2000. The areas of greatest abundance of wintering waterfowl within the Central Valley shifted northward as many species responded to changes in the distribution of habitats. Wintering waterfowl migrated earlier in fall and winter from the San Joaquin Valley, Suisun Marsh, and Delta to the Sacramento Valley, and fewer waterfowl emigrated from the Sacramento Valley to other parts of the Central Valley. Because changes in waterfowl distribution were primarily a response to the increase of a beneficial agricultural practice (i.e., the flooding of rice after harvest) in the Sacramento Valley, changing agro-economics, reduction of water supplies, or other factors that reduce this practice could change the abundance and distribution of wintering waterfowl in the Central Valley rapidly. Thus to maintain abundant suitable habitat and restore the historical distribution of wintering waterfowl, our results suggest a continuing need for the conservation of wetlands and other waterfowl habitats with secure water supplies throughout the Central Valley. Despite our findings, achieving goals for winter waterfowl populations in the Central Valley likely will depend on a combination of factors including some acting in breeding ranges farther north or elsewhere outside of the valley.

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USGS1984

Evaluation of a technique for simulating a compacting aquifer system in the Central Valley of California, USA

Large volumes of water have been pumped from the Central Valley aquifer system since the early 1900's. Water levels in the most heavily pumped areas had declined as much as 120 m by 1970. These large water-level declines resulted in approximately 21,000 hm3 of water released by inelastic compaction of numerous compressible fine-grained deposits. The principal technique used to evaluate the aquifer system was a three-dimensional computer program that solves the basic ground-water flow equation. The program was modified to incorporate water released by inelastic compaction of the fine-grained deposits by making storage a function of hydraulic head. The computer-simulated volume of water released from inelastic compaction for the period from 1961 through 1977 was 6 percent of the estimated volume. The technique could be used in other areas where water is released as a result of inelastic compaction of fine-grained deposits.

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