Shasta Valley Groundwater Sustainability Plan

Siskiyou County Flood Control and Water Conservation District | January 28th, 2022

SGMA was established to provide local and regional agencies the authority to sustainably manage groundwater resources through the development and implementation of GSPs

SGMA was established to provide local and regional agencies the authority to sustainably manage groundwater resources through the development and implementation of GSPs for high and medium priority subbasins (e.g., Shasta Valley). In accordance with SGMA, this GSP was developed and will be implemented by the GSA representing the Basin: the Siskiyou County Flood Control and Water Conservation District. To deal with file size, the Shasta Valley GSP has been divided into three files: Part 1, Part 2,  Part 3 Plan approved by DWR

Shifting Baselines in a California Oak Savanna: Nineteenth Century Data to Inform Restoration Scenarios

Restoration Ecology, Society for Ecological Restoration (SER) | January 6th, 2011

For centuries humans have reduced and transformed Mediterranean‐climate oak woodland and savanna ecosystems, making it difficult to establish credible baselines for eco

For centuries humans have reduced and transformed Mediterranean‐climate oak woodland and savanna ecosystems, making it difficult to establish credible baselines for ecosystem structure and composition that can guide ecological restoration efforts. We combined historical data sources, with particular attention to mid‐1800s General Land Office witness tree records and maps and twentieth century air photos, to reconstruct 150 years of decline in extent and stand density of Valley oak (Quercus lobata Neé) woodlands and savannas in the Santa Clara Valley of central coastal California. Nineteenth century Valley oak woodlands here were far more extensive and densely stocked than early twentieth century air photos would suggest, although reconstructed basal areas (7.5 m2/ha) and densities (48.9 trees/ha) were not outside the modern range reported for this ecosystem type. Tree densities and size distribution varied across the landscape in relation to soil and topography, and trees in open savannas were systematically larger than those in denser woodlands. For the largest woodland stand, we estimated a 99% decline in population from the mid‐1800s to the 1930s. Although most of the study area is now intensely developed, Valley oaks could be reintroduced in urban and residential areas as well as in surrounding rangelands at densities comparable to the native oak woodlands and savannas, thereby restoring aspects of ecologically and culturally significant ecosystems, including wildlife habitat and genetic connectivity within the landscape.

Shifting landscapes: decoupled urban irrigation and greenness patterns during severe drought

Environmental Research Letters (IOP) | June 7th, 2019

Urban outdoor water conservation and efficiency offer high potential for demand-side management, but irrigation, greenness, and climate interlinks must be better underst

Urban outdoor water conservation and efficiency offer high potential for demand-side management, but irrigation, greenness, and climate interlinks must be better understood to design optimal policies. To identify paired transitions during drought, we matched parcel-level water use data from smart, dedicated irrigation meters with high-spatial resolution, multispectral aerial imagery. We examined changes across 72 non-residential parcels using potable or recycled water for large landscape irrigation over four biennial summers (2010, 2012, 2014, and 2016) that encompassed a historic drought in California. We found that despite little change in irrigation levels during the first few years of the drought, parcel greenness deteriorated. Between summers 2010 and 2014, average parcel greenness decreased−61% for potable water irrigators and−56% for recycled water irrigators, providing evidence that vegetation could not reach its vigor from wetter, cooler years as the drought intensified with abnormally high temperatures. Between summers 2014–2016 as drought severity lessened, irrigation rates decreased significantly in line with high drought saliency, but greenness rebounded ubiquitously, on average+110% for potable water irrigators and+62% for recycled water irrigators, demonstrating climate-driven vegetation recovery as evaporation and plant evapotranspiration rates decreased. Transitions were similar for customers with both potable and recycled water; vegetation changes were dominated by the overarching climatic regime. As irrigation cannot always overcome drought conditions, which will become more severe under climate change, to maintain vegetation health, utilities and urban planners should consider the tradeoffs between providing green spaces and water scarcity. This includes evaluating the roles of climate-appropriate landscaping and adaptive reallocation of potable and recycled water resources to enhance water security. By addressing emerging themes in urban water management through analysis of data from forthcoming water metering and aerial imagery technologies, this research provides a unique perspective on water use, greenness, and drought linkages.

Shifting shores: Marsh expansion and retreat in San Pablo Bay

San Francisco Estuary Institute (SFEI) | June 30th, 2015

As sea level rise accelerates, our shores will be increasingly vulnerable to erosion. Particular concern centers around the potential loss of San Francisco Bay’s much-v

As sea level rise accelerates, our shores will be increasingly vulnerable to erosion. Particular concern centers around the potential loss of San Francisco Bay’s much-valued tidal marshes, which provide natural flood protection to our shorelines, habitat for native wildlife, and many other ecosystem services. Addressing this concern, this study is the first systematic analysis of the rates of marsh retreat and expansion over time for San Pablo Bay, located in the northern part of San Francisco Bay. Key findings: • Over the past two decades, more of the marshes in San Pablo Bay have expanded (35% by length) than retreated (6%). • Some areas have been expanding for over 150 years. • Some marsh edges that appear to be retreating are in fact expanding rapidly at rates of up to 8 m/yr. • Marsh edge change may be a useful indicator of resilience, identifying favorable sites for marsh persistence. • These data can provide a foundation for understanding drivers of marsh edge expansion and retreat such as wind direction, wave energy, watershed sediment supply, and mudflat shape. • This understanding of system dynamics will help inform management decisions about marsh restoration and protection. • This study provides a baseline and method for tracking marsh edge response to current and future conditions, particularly anticipated changes in sea level, wave energy, and sediment supply. Recommended next steps: • This pilot study for San Pablo Bay marshes should be extended to other marshes in San Francisco Bay. • These initial marsh expansion and retreat findings should be further analyzed and interpreted to improve our understanding of system drivers and identify management responses. • A program for repeated assessment should be developed to identify and track changes in shoreline position, a leading indicator of the likelihood marsh survival.

Shifts in MJO behavior enhance predictability of subseasonal precipitation whiplashes

Nature Portfolio (Springer Nature) | April 28th, 2025

Shifts in the thermal niche of almond under climate change

Climatic Change (Springer) | December 5th, 2017

Delineating geographic shifts in crop cultivation under future climate conditions provides information for land use and water management planning, and insights to meeting

Delineating geographic shifts in crop cultivation under future climate conditions provides information for land use and water management planning, and insights to meeting future demand. A suitability modeling approach was used to map the thermal niche of almond cultivation and phenological development across the Western United States (US) through the mid-21st century. The Central Valley of California remains thermally suitable for almond cultivation through the mid-21st century, and opportunities for expansion appear in the Willamette Valley of western Oregon, which is currently limited by insufficient heat accumulation. Modeled almond phenology shows a compression in reproductive development under future climate. By the mid-21st century, almond phenology in the Central Valley showed ~ 2-week delay in chill accumulation and ~ 1- and ~ 2.5-week advance in the timing of bloom and harvest, respectively. Although other climatic and non-climatic restrictions to almond cultivation may exist, these results highlight opportunities for shifts in the geography of high-value cropping systems, which may influence growers’ long-term land use decisions, and shape regional water and agricultural industry discussions regarding climate change adaptation options.

Shoreline retreat and beach nourishment are projected to increase in Southern California

Nature Portfolio (Springer Nature) | May 22nd, 2024

Sandy beaches in Southern California are experiencing rising coastal erosion due to changes in precipitation patterns and urban growth. As a result, beach nourishment is

Sandy beaches in Southern California are experiencing rising coastal erosion due to changes in precipitation patterns and urban growth. As a result, beach nourishment is necessary for mitigation. In our study, we forecast the rates of shoreline retreat and the required volumes of sand nourishment to mitigate it for the coming decades. We employ photogrammetric multi-decadal shoreline positioning and Digital Shoreline Analysis System methods to measure and predict the coastal evolution of the Gulf of Santa Catalina in Southern California. This region is hypothesized to be globally representative of other semi-arid sandy coasts facing similar hydroclimatic and anthropogenic challenges. Our findings indicate that Southern California’s shoreline retreat rates for sandy beaches will increase from the present average value of ~−1.45 to −2.12 meters per year in 2050 and to −3.18 meters per year in 2100. Consequently, the annual volume of sand required for beach nourishment could triple by 2050, increasing from the present-day amount of ~1223 to ~3669 cubic meters per year per kilometer. However, the associated cost for this nourishment will grow five times, exacerbating several coastal communities’ economic and logistical pressures. Similar trends are emerging globally, with semi-arid developing nations already grappling with coastal hazards and may struggle to manage the escalating costs of curbing beach nourishment.

Shoreline Seasonality of California's Beaches

American Geophysical Union (AGU) | January 30th, 2025

We report on remote sensing techniques developed to characterize seasonal shoreline cycles from satellite-derived shoreline measurements. These techniques are applied to

We report on remote sensing techniques developed to characterize seasonal shoreline cycles from satellite-derived shoreline measurements. These techniques are applied to 22-yr of shoreline measurements for over 777 km of beach along California's 1,700-km coast, for which the general understanding is that shorelines exhibit winter-narrow and summer-recovery seasonality. We find that approximately 90% of beach transects exhibit significant and recurring seasonal cycles in the shoreline position. Seasonal shoreline excursions are twice as large in northern and central California (17.5–32.2 m) than southern California (7.3–15.9 m; interquartile ranges). Clustering analyses were effective at characterizing the temporal patterns of the seasonality, revealing that ∼459 km of beach (59%) exhibit winter-narrow conditions, whereas ∼189 km (24%) and ∼50 km (6.4%) exhibit spring-narrow and summer-narrow conditions, respectively. These spring- and summer-narrow conditions are most common in southern California, where they represent over half of the total length of beach shoreline. Multivariate analyses reveal that wave climate and geomorphic setting are significantly related to the magnitude and timing of shoreline seasonal cycles. Combinations of these variables explain 44% of the seasonality variance of the complete data set and 85% of the variance for a subset of 93 long (>1 km) continuous beaches. We conclude that diversity in waves and geomorphic setting along California cause a broad range of seasonal patterns in the shoreline. Combined, this indicates that the overly generalized “winter-narrow/summer-recovery” conventions for California beaches are not expressed universally and that shoreline seasonality is far more diverse than these simple canonical rules.

Short-lived pause in Central California subsidence after heavy winter precipitation of 2017

American Association for the Advancement of Science (AAAS) | August 29th, 2018

The Tulare Basin in Central California is a site of intensive agricultural activity and extraction of groundwater, with pronounced ground subsidence and degradation of wa

The Tulare Basin in Central California is a site of intensive agricultural activity and extraction of groundwater, with pronounced ground subsidence and degradation of water resources over the past century. Spatially extensive observations of ground displacements from satellite-based remote sensing allow us to infer the response of the aquifer system to changes in usage and to marked recharge events such as the heavy winter rainfall in 2017. Radar imagery from the Sentinel-1a/b satellites (November 2014 to October 2017) illuminates secular and seasonal trends modulated by changes in withdrawal rates and the magnitude of winter precipitation. Despite the increased precipitation in early 2017 that led to a marked decrease, or in some areas, reversal, of subsidence rates, subsidence returned to rates observed during the drought within a matter of months.

Short‐lived pause in Central California subsidence after heavy winter precipitation of 2017

American Association for the Advancement of Science (AAAS) | August 29th, 2018

The Tulare Basin in Central California is a site of intensive agricultural activity and extraction of groundwater, with pronounced ground subsidence and degrada

The Tulare Basin in Central California is a site of intensive agricultural activity and extraction of groundwater, with pronounced ground subsidence and degradation of water resources over the past century. Spatially extensive observations of ground displacements from satellite-based remote sensing allow us to infer the response of the aquifer system to changes in usage and to marked recharge events such as the heavy winter rainfall in 2017. Radar imagery from the Sentinel-1a/b satellites (November 2014 to October 2017) illuminates secular and seasonal trends modulated by changes in withdrawal rates and the magnitude of winter precipitation. Despite the increased precipitation in early 2017 that led to a marked decrease, or in some areas, reversal, of subsidence rates, subsidence returned to rates observed during the drought within a matter of months.