Assessing the Effects of Climate Change on Middle Rio Grande Surface Water Supplies Using a Simple Water Balance Reservoir Model

American Meteorological Society (AMS) | August 12th, 2022

The middle Rio Grande is a vital source of water for irrigation in the region. Climate change is impacting regional hydrology and is likely to put additional stress on a

The middle Rio Grande is a vital source of water for irrigation in the region. Climate change is impacting regional hydrology and is likely to put additional stress on a water supply that is already stretched thin. To gain insight on the hydrologic effects of climate change on reservoir storage, a simple water balance model was used to simulate the Elephant Butte–Caballo Reservoir system (southern New Mexico). The water balance model was forced by hydrologic inputs generated by 97 climate simulations derived from CMIP5 global climate models, coupled to a surface hydrologic model. Results suggest that the percentage of years that reservoir releases satisfy agricultural water rights allocations over the next 50 years (2021–70) will decrease relative to the past 50 years (1971–2020). The modeling also projects an increase in multiyear drought events that hinder reservoir management strategies to maintain high storage levels. In most cases, changes in reservoir inflows from distant upstream snowmelt is projected to have a greater influence on reservoir storage and water availability downstream of the reservoirs than will changes in local evaporation and precipitation from the reservoir surfaces.

Balancing Flood Risk and Water Supply in California: Policy Search Integrating Short-Term Forecast Ensembles With Conjunctive Use

American Geophysical Union (AGU) | September 24th, 2018

Short-term weather forecasts have the potential to improve reservoir operations for both flood control and water supply objectives, especially in regions currently relyin

Short-term weather forecasts have the potential to improve reservoir operations for both flood control and water supply objectives, especially in regions currently relying on fixed seasonal flood pools to mitigate risk. The successful development of forecast-based policies should integrate uncertainty from modern forecast products to create unambiguous rules that can be tested on out-of-sample periods. This study investigates the potential for such operating policies to improve water supply efficiency while maintaining flood protection, combining state-of-the-art weather hindcasts with downstream conjunctive use to transfer surplus flood releases to groundwater storage. Because available weather hindcasts are relatively short (10–20 years), we propose a novel statistical framework to develop synthetic forecasts over longer periods of the historical record. Operating rules are trained with a recently developed policy search framework in which decision rules are structured as binary trees. Policies are developed for a range of scenarios with varying forecast skill and conjunctive use capacity, using Folsom Reservoir, California, as a case study. Results suggest that the combination of conjunctive use and short-term weather forecasts can substantially improve both water supply and flood control objectives by allowing storage to remain high until forecasts trigger a release. Further, increased conjunctive use capacity reduces the importance of forecast skill, since surface storage can be moved to groundwater during the flood season without losing water supply. This analysis serves the development of forecast-based operating policies for large, multipurpose reservoirs in California and other regions with similar flood hydroclimatology.

Bay Area Water Supply Resilience and the Bay-Delta Plan

Publisher not available | March 15th, 2024

Beneath the Surface: Why Reservoirs Won't Solve California's Water Woes

Center for Biological Diversity (CBD) | November 19th, 2024

Water storage and conveyance have fundamentally shaped modern California. The vast agricultural industry, as well as globally important cities like Los Angeles, were made

Water storage and conveyance have fundamentally shaped modern California. The vast agricultural industry, as well as globally important cities like Los Angeles, were made possible by storing and moving water around the state. Reservoirs are one of the primary components of California’s water storage system. There are nearly 1,500 surface storage reservoirs throughout the state, which together can store a year’s supply of water for farms and cities. But reservoirs come with high costs. They destroy and degrade habitats and alter flows in rivers and streams, harming native fish and wildlife. They emit significant amounts of greenhouse gases, worsening climate change. They cost taxpayers billions of dollars to build and maintain. And as the climate continues to warm, reservoirs will become less efficient, losing more and more of the water they hold to evaporation.  This report examines reservoirs’ environmental harms and explains why new reservoirs are not the solution to our 21st century water problems. 

Benefits and Economic Costs of Managed Aquifer Recharge in California

University of California, Davis (UC Davis) | July 14th, 2016

Groundwater management is important and challenging, and nowhere is this more evident than in California. Managed aquifer recharge (MAR) projects can play an important ro

Groundwater management is important and challenging, and nowhere is this more evident than in California. Managed aquifer recharge (MAR) projects can play an important role in ensuring California manages its groundwater sustainably. Although the benefits and economic costs of surface water storage have been researched extensively, the benefits and economic costs of MAR have been little researched. Historical groundwater data are sparse or proprietary within the state, often impairing groundwater analyses. General obligation bonds from ballot propositions offer a strategic means of mining information about MAR projects, because the information is available publicly. We used bond-funding applications to identify anticipated MAR project benefits and proposed economic costs. We then compared these costs with actual project costs collected from a survey, and identified factors that promote or limit MAR. Our analysis indicates that the median proposed economic cost for MAR projects in California is $410 per acre-foot per year ($0.33 per m3 per year). Increasing Water Supply, Conjunctive Use, and Flood Protection are the most common benefits reported. Additionally, the survey indicates that (1) there are many reported reasons for differences between proposed and actual costs ($US 2015) and (2) there is one primary reason for differences between proposed recharge volumes and actual recharge volumes (AFY): availability of source water for recharge. Although there are differences between proposed and actual costs per recharge volume ($US 2015/AFY), the ranges for proposed costs per recharge volume and actual costs per recharge volume for the projects surveyed generally agree. The two most important contributions to the success of a MAR project are Financial Support and Good Communication with Stakeholders.

Bulletin 17-65, Dams within Jurisdiction of the State of California

California Department of Water Resources (DWR) | August 31st, 1965

Bulletin 17-71, Dams within Jurisdiction of the State of California

California Department of Water Resources (DWR) | October 29th, 1971

Bulletin 17-74, Dams within Jurisdiction of the State of California

California Department of Water Resources (DWR) | May 31st, 1974

Bulletin 17-76, Dams within Jurisdiction of the State of California

California Department of Water Resources (DWR) | July 30th, 1976

Bulletin 17-79, Dams within Jurisdiction of the State of California

California Department of Water Resources (DWR) | December 29th, 1979