Decision Scaling Evaluation of Climate Risks to the State Water Project

California Department of Water Resources (DWR) | May 29th, 2019

This Final Decision Scaling Vulnerability Assessment Report updates and describes a joint endeavor of the California Department of Water Resources (DWR) and the Universit

This Final Decision Scaling Vulnerability Assessment Report updates and describes a joint endeavor of the California Department of Water Resources (DWR) and the University of Massachusetts, Amherst (UMass) to improve planning for the uncertain effects of climate change on the California Central Valley Water System (CVS)1 by integrating vulnerability-based analysis with traditional risk-based assessment methods. This report summarizes the research goals, analytical approach, workflow of modeling tools, evaluation of alternative experimental designs, refined strategy for data visualization, and assessment of the vulnerability of the CVS to climate change.  This report begins with a review of historical and projected climate change in California, which includes descriptions of several DWR-UMass team investigations of historical records, observed climate trends, and many climate projections for the CVS, specifically. The next section of this report summarizes the work previously accomplished by the academic community, the government, and the community of water resources practitioners evaluating climate change-related risks to the CVS.  With that background in place, this report explains the methodology developed for this study (illustrated in Figure ES1) and provides details on each sub-step of the process. Whereas previous studies have tested the response of some aspect of the California water system to ahistorical climate traces, the decision scaling approach adopted for this study allows systematic assessment of the vulnerability of the entire (interconnected and complex) CVS to a wide range of potential future climate conditions, and quantification of the significance of climate shift relative to natural (and climate-change-amplified) variability. The climate response function that results from the decision scaling approach depicts expected water system performance relative to historical performance across a range of climate changes. An important benefit of this approach is the ability to use a variety of climate information sources to assess the level of concern to assign to the vulnerabilities that are identified. Consequently, climate information, including climate change projections and formal probability estimates, can be used as a sensitivity factor when assessing risk, rather than the driver of the analysis. This allows discussion of risk and opportunity (each a function of impact and likelihood) in water system investment.  This assessment of long-term and persistent hydrologic impacts of climate change focuses on the effects to the operation of the State Water Project (SWP), including ecological conditions that dictate operating rules. DWR owns and operates the SWP for flood control, maintenance of environmental and water quality conditions, water supply, hydropower, and recreation. Consequently, analysis of SWP performance under climate-changed conditions yields an array of impact metrics across these areas of concern. The analysis focuses on persistent medium- and long-term conditions evaluated at a monthly time-step. Short-duration extreme precipitation events that cause flooding may also stress water resource management but are beyond the scope of this study.  This study has adopted CalLite 3.0 to simulate the coordinated operations of the Central Valley Project (CVP) and SWP under a wide range of climate possibilities. Climate traces are developed through coupling historical daily temperature and precipitation (1950–2013) (Livneh et al. 2013) to the paleo-dendrochronological reconstructed streamflow record of the Sacramento-4-river annual streamflow (900–2013) (Meko et al. 2014). An advanced hydrologic model, the Sacramento Soil Moisture Accounting distributed hydrologic model (SAC-SMA-DS), translates the hydroclimatic traces into streamflow, which are the key inputs to the water system model.

Declining Freshwater Availability in the Colorado River Basin Threatens Sustainability of Its Critical Groundwater Supplies

American Geophysical Union (AGU) | May 27th, 2025

Climate change is causing more frequent and intense droughts around the world, including in the Colorado River Basin, which supplies water to seven U.S. states and Mexico

Climate change is causing more frequent and intense droughts around the world, including in the Colorado River Basin, which supplies water to seven U.S. states and Mexico, and is facing severe water shortages. This study investigates how changes in water storage components (e.g., snow, surface water, soil moisture and groundwater) and water use are contributing to these shortages, and impacting agriculture and municipal water supplies, using data from the NASA GRACE and GRACE Follow-On (GRACE-FO) satellite missions, land surface models, and in situ data over the past two decades. Results show significant losses of groundwater: 7.8.0 ± 5.3 km3 in the Upper CRB (UCRB) and 25.5 ± 7.4 km3 in the Lower CRB (LCRB). Progress toward sustainable groundwater could be achieved by reducing groundwater extraction, in line with current rates of depletion (0.35 km3 in the UCRB and 1.15 km3 in the LCRB). This research highlights the importance of understanding the factors affecting groundwater levels to create sustainable water management strategies that can help secure water resources for the region's future.

Defining urban resilience: A review

Landscape and Urban Planing (Elsevier) | March 1st, 2016

Fostering resilience in the face of environmental, socioeconomic, and political uncertainty and risk has captured the attention of academics and decision makers across di

Fostering resilience in the face of environmental, socioeconomic, and political uncertainty and risk has captured the attention of academics and decision makers across disciplines, sectors, and scales. Resilience has become an important goal for cities, particularly in the face of climate change. Urban areas house the majority of the world's population, and, in addition to functioning as nodes of resource consumption and as sites for innovation, have become laboratories for resilience, both in theory and in practice. This paper reviews the scholarly literature on urban resilience and concludes that the term has not been well defined. Existing definitions are inconsistent and underdeveloped with respect to incorporation of crucial concepts found in both resilience theory and urban theory. Based on this literature review, and aided by bibliometric analysis, the paper identifies six conceptual tensions fundamental to urban resilience: (1) definition of ‘urban’; (2) understanding of system equilibrium; (3) positive vs. neutral (or negative) conceptualizations of resilience; (4) mechanisms for system change; (5) adaptation versus general adaptability; and (6) timescale of action. To advance this burgeoning field, more conceptual clarity is needed. This paper, therefore, proposes a new definition of urban resilience. This definition takes explicit positions on these tensions, but remains inclusive and flexible enough to enable uptake by, and collaboration among, varying disciplines. The paper concludes with a discussion of how the definition might serve as a boundary object, with the acknowledgement that applying resilience in different contexts requires answering: Resilience for whom and to what? When? Where? And why?

Degradation of floodplain integrity within the contiguous United States

Nature Portfolio (Springer Nature) | June 15th, 2023

Delano Earlimart Irrigation District Groundwater Sustainability Plan

Delano Earlimart Irrigation District | January 27th, 2020

Delta Adapts: Creating a Climate Resilient Future

Delta Stewardship Council (DSC) | June 25th, 2025

The Delta Stewardship Council (Council) was established, in part, to provide sustainable management for the Delta ecosystem, and climate adaptation is a critical consider

The Delta Stewardship Council (Council) was established, in part, to provide sustainable management for the Delta ecosystem, and climate adaptation is a critical consideration to achieve that mission in future decades. To respond to the challenge of climate adaptation,the Council developed this initiative, Delta Adapts: Creating a Climate Resilient Future (Delta Adapts). Climate change must be considered to attain the state’s coequal goals, as established by the 2009 Delta Reform Act: securing a reliable water supply for California, protecting and restoring the ecosystem and wildlife it supports, and enhancing the Delta as a unique place, with its community, tribal, and agricultural heritage. The Council adopted the Delta Plan, which has regulatory policies that protect land for restoration and agriculture, help manage flood risk, and improve water supply reliability. The Delta Plan directs the Council to guide and regulate actions of the 200+ state and local agencies in the Delta to ensure they support statewide water supply reliability and Delta ecosystem restoration.

Delta Aquatic Resources Inventory Factsheet

San Francisco Estuary Institute (SFEI) | July 1st, 2019

 DARI is the Delta Aquatic Resources Inventory of surface waters, wetlands and other aquatic resources in the Sacramento-San Joaquin Delta (Delta). The goal of the DARI

 DARI is the Delta Aquatic Resources Inventory of surface waters, wetlands and other aquatic resources in the Sacramento-San Joaquin Delta (Delta). The goal of the DARI project is to develop a geospatial inventory of aquatic resources that will be used as a common base map for the Delta. A similar mapping approach used to create the California Aquatic Resource Inventory (CARI; www. sfei.org/cari) will be applied to provide a map of the aquatic resources and their associated attributes. The final map will be incorporated into CARI and made publicly available through EcoAtlas (ecoatlas.org) and similar platforms. 

Delta Conveyance Project Final Environmental Impact Report

California Department of Water Resources (DWR) | December 8th, 2023

Delta Conveyance Project Operations Plan

California Department of Water Resources (DWR) | August 23rd, 2024

This document presents a summary of the Delta Conveyance Project (DCP) operations commitments that the Department of Water Resources (DWR) has made for when the DCP becom

This document presents a summary of the Delta Conveyance Project (DCP) operations commitments that the Department of Water Resources (DWR) has made for when the DCP becomes operational.

Delta Conveyance Project: Modernizing California’s Water Infrastructure, Fast Facts 2024

California Department of Water Resources (DWR) | September 13th, 2023