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Projects Worked On

Project Name Description
California Water Myths

In collaboration with the Public Policy Institute of California and other researchers, the Center prepared California Water Myths—a report highlighting eight common water myths, focusing on water supply, ecosystems and legal and governance issues. In providing information to combat these myths, the study establishes a more informed approach to water policy and management in California.

Myths of California Water: Virtual Tour was created as a interactive companion to the California Water Myths report. Experience aerial views of California in locations that relate to the myths and get in-depth information about the realities that combat these myths. The tour also provides links to visual images and further reading.

Addressing Nitrate in California's Drinking Water

One in 10 people living in California’s most productive agricultural areas is at risk of exposure to harmful levels of nitrate contamination in their drinking water, according to a report released today by the University of California, Davis. The report was commissioned by the State Water Resources Control Board.

The report, “Addressing Nitrate in California’s Drinking Water,” is the first comprehensive scientific investigation of nitrate contamination in the Tulare Lake Basin, which includes Fresno and Bakersfield, and the Salinas Valley, which includes Salinas and areas near Monterey. It defines the extent of the problem, suggests promising solutions and outlines possible funding mechanisms.


California’s complex water management system often defies comprehensive analysis. We summarize the results of a decade of quantification and analysis of this system from a hydro-economic perspective using the CALVIN Model.

The general approach taken dates back to Roman times, when Frontinus (97 AD) began his oversight of Rome’s water system with a systematic inventory and quantification of its water infrastructure. 

This approach has been formalized and expanded in the modern era as economists, planners, and engineers have sought to grapple with complex water management systems and problems.

In California water supply and demand is inconvenient in both space and time. Most water availability is in northern California from winter precipitation and spring snow-melt; whereas water demands are more in the south during the dry summer. Major floods and seasonal and multiyear droughts further complicate water resource management in California. The Sacramento-San Joaquin Delta is the major north-south hub for this water network.

Population growth, climate change, a vulnerable Delta, and decentralized water governance pose opportunities and challenges to water management in California. Portfolios of water management activities, including diverse general policy tools, demand management, and operations and supply expansion options, are available to manage competing demands in complex situations.

Exploring promising portfolios of actions is the main intent of the CALVIN model. The CALVIN model is an economic-engineering optimization model of California developed at the University of California – Davis. CALVIN’s major innovations are its statewide (rather than project) scale, representation of a broad range of water management options, explicit integration of broad economic objectives, and its consequent applicability to a wide variety of policy, operations, and planning problems.



Water resource management in California is often extensive and complex and deserves a comprehensive data and modeling approach. The Hobbes Project is a new effort to provide a venue for modelers in California and elsewhere to create an open, organized and documented quantitative representation of the state's intertied water resources system. Geocoded elements in this database can be interactively converted into tiered networks able to be solved by multiple modeling platforms depending on user preferences, with the appropriate translators. Many Hobbes tools will be web-based with exporting capabilities to the most common analytical and modeling software.

The Hobbes Project will include:

  • Database standardization and data documentation

  • Geocoded data element representations

  • Open platform with web access

  • Ability to transform database elements into documented model inputs via co-development

  • Focus on data and database structure, organization, documentation, not specific models

As shown in Figure 1, users of the Hobbes Project will be able to visualize different documented elements in a common web-based mapping application, run specific modeling networks using either the Hobbes basic database, network managers scenario manager software pieces and visualize model outputs in tabular form, chart templates, maps or simply exporting the modeling network, its input data and/or its modeling output to be used in other platforms.

For more information, please see the project website at


Yolo Bypass: Managing a floodplain for multiple uses

This study will present a decision-making framework for balancing ecosystem and economic goals on the Yolo Bypass, a promising site for habitat restoration in the San Francisco Bay-Delta system. The bypass's primary purpose is to provide flood control for Sacramento, but it's also used for farming, duck hunting and bird-watching. We're developing an optimilization model to explore when, where and how floodwaters might most economically be applied to manage all the diverse activities.


The video (above) demonstrates our application of a newly developed flood simulation software (HEC-RAS-2D) to the Yolo Bypass. The model will help us determine whether solutions from the optimization analysis are realistic. If an optimal solution calls for engineered modifications to the floodplain, we can use the model to test the effects of those potential changes. The decision-making framework and tools we develop will be applicable to other floodplain restoration efforts in California and elsewhere.


Related news and commentary:

Sacramento River Flood Control Project

California is looking to expand the Sacramento River Flood Control Project, partly as a defense against severe storms in a changing climate. This study creates a model of the Project for exploring various scenarios. Researchers are analyzing how the system's bypass channels and weirs interact during big storms and how expansions of these structures might reduce flood damage at various locations in the Sacramento Valley and the Delta. 



Water Modeling in Agricultural Production



This  technical workshop in collaboration with the California Water and Enviornmental Modeling Forum (CWEMF). This workshop presents various alternatives for modeling the economics of water use and water scarcity within an agricultural production setting, with a particular focus on California. This 6-hour workshop at UC Davis is intended to bring experts and interested water resources professionals from academia, industry and government agencies to talk and learn about various models and optimization tools that have been used to evaluate the economics surrounding agricultural water use  in California, Australia, Chile, and México. Applications using both mathematical programming and hedonic models will be presented.  A discussion about modeling needs and future applications for the California water modeling community will be encouraged.  

See the links below for workshop compressed file. or workshop folder link

If you attended the workshop, please respond to our survey.

Please get the following workshop materials (updated February 4, 2014):

 1) Hands on examples

2) blank Excel template, and 

3) the Excel worked examples for your reference 


Drought's Economic Impact on Agriculture

UC Davis researchers forecast the socio-economic effects of the drought on California agriculture for 2014 and beyond. Economists use computer models and the latest estimates of water deliveries, well-pumping capacities and acres fallowed. The researchers exploit new satellite remote-sensing technologies to estimate fallowed acreage as the drought unfolds.

2016 Study Downloads


Economic Analysis of the 2016 California Drought for Agriculture (California Water Blog, August 15, 2016)

Estimates of Irrigated Cropland Idled due to the 2016 California Drought: Clarifications and Supplemental Information (NEW! Memorandum, September 1, 2016)


Collaborators: Duncan MacEwan

Daniel Sumner 

Integrated Environmental Modeling

Integrated Modeling for Adaptive Management of Estuarine Systems


May 21-22, 2015, UC Davis Campus

Like many estuarine systems, California’s Sacramento-San Joaquin Delta needs to revolutionize how models and data are developed and integrated to support adaptive management. Durable and adaptive solutions must account for a cascade of interacting social, economic, and ecological effects.

The National Science Foundation is sponsoring an Integrated Modeling Workshop to explore ways to improve the development and application of modeling for multipurpose management of changing estuarine systems. The two-day workshop will bring together experts from Europe, Asia and across the U.S. Potential solutions will be identified and discussed from multiple perspectives: government, academia, NGOs, consultants and stakeholders.

Approaches to be discussed include:

Community modeling leverages the expertise of many public, private, NGO, and academic researchers for understanding complex environmental problems and supporting adaptive management. Community modeling is a way to connect experts on each of the system components through a common framework. Community modeling requires a sustainable business model that works across agencies, universities, NGOs and the private sector.

Public domain models and data can include open source and more proprietary and controlled approaches to develop software and data. Such approaches are especially important where a broad common understanding must be developed among many interests and where alternatives must be compared with transparency and minimal cost.

Integrated Environmental Modeling (IEM) uses information technologies to couple independently developed models. Modular modeling components are assembled flexibly to explore, explain, and forecast the behavior of various system purposes. IEM systems around the world include diverse stand-alone applications and high performance computer clusters.

Workshop Program (Updated May 19, 2015)

  • Integrated Environmental Modeling
  • Decision support systems: science/modeling organizations that bridge the science-policy gap
  • Directions for improved integrated modeling of estuarine systems

The workshop is organized by the Delta Stewardship Council/Delta Science Program and UC Davis Center for Watershed Sciences. The National Science Foundation is sponsoring the event in partnership with the California Water and Environmental Modeling Forum and the International Association for Hydro-Environment Engineering and Research.


Student stipends are available on a first come first serve basis. Please fill out the student stipend request form. We can provide an stipend of $100 if located around 50 mi from Davis, $150 if located between 51 and 150 miles from Davis and $300 beyond 150 miles including out of state. 


This workshop was supported by the National Science Foundation under Award: A Workshop on Community Integrated Environmental Models (Grant Number 1464440).  The Organizing Committee acknowledges supplemental support by the Delta Stewardship Council through the Delta Science Program and the Center for Watershed Sciences. 


"Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation."

Collaborators: Christopher Enright

Peter Goodwin

Delta Consumptive Water Use Comparative Study

Delta Consumptive Water Use Comparative Study

Josué Medellín-Azuara, Principal Investigator, Center for Watershed Sciences

Kyaw Tha Paw U, Yufang Jin, Jay R. Lund, Co-Principal Investigators

Quinn Hart, Eric Kent, Jenae Clay, Andy Wong

University of California, Davis

Michelle M Leinfelder-Miles, UC Cooperative Extension

Other collaborators and research support from:

Andrew Bell, Martha Anderson, Daniel Howes, Forrest Melton, Tariq Kadir, Morteza Orang, Michelle M. Leinfelder-Miles, Jay R. Lund, J. Andrés Morandé, William Li, Christine Rico, John Collins, Michael George (Waterboards) 

Funded convened by the Office of the Delta Watermaster

State Water Resources Control Board, California Department of Water Resources, Delta Protection Commission, Delta Stewardship Council, North Delta Water Agency, Central Delta Water Agency,  South Delta Water Agency, Center for Watershed Sciences and UC Water


A better overall understanding of consumptive use (CU) in the Delta is critical not only to water rights administration, but also to water project management, agricultural irrigation management, and to environmental and water quality protection. The purpose of this project is to develop a better understanding of CU in the Delta, to coordinate efforts and information derived from independent research efforts, and to consolidate information about methods for measuring CU within the Delta. The Center for Watershed Sciences will gather, analyze, and disseminate data about actual direct evaporation and plant transpiration in the Delta (sometimes referred to as evapotranspiration, or ET) and organize and use the ET data to facilitate comparative tests of up to seven selected methods for measuring CU:

The methods employed by the seven independent research teams to estimate crop ET are:

  • California Simulation of Evapotranspiration of Applied Water, “CalSIMETAW” (California Department of Water Resources - DWR),
  • Delta Evapotranspiration of Applied Water, “DETAW” (DWR),
  • Disaggregate Atmosphere-Land Exchange Inverse, “DisAlexi” (United States Department of Agriculture - Agricultural Research Service - ARS),
  • Mapping EvapoTranspiration at high Resolution with Internalized Calibration, “METRIC” (California Polytechnic Institute, San Luis Obispo - Irrigation Training and Research Center - ITRC),
  • METRIC (University of California, Davis - UC Davis),
  • Satellite Irrigation Management Support system, “SIMS” (National Aeronautics and Space Administration - Ames Research Center- NASA), and
  • Priestley-Taylor (UC Davis). 

In addition, CWS will access existing and emerging data developed under other ongoing research efforts to augment and inform the CU investigation. The CWS will coordinate with independent researchers so as to benefit from their parallel efforts to provide more comprehensive understanding of CU in the Delta.

Additionally, a study to compare Actual Evapotranspiration (ET) estimates between Landsat 8 coarse resolution (30 meters-pixel) and unmanned aerial vehicle (UAV) fine resolution (1.0 meter-pixel) was carried out in crops of alfalfa, pasture and maize. Findings showed that ET mapping at high resolution delivers relevant data that is not possible to detect at Landsat 8 scale. UAV showed higher level of ET spatial variability (up to 75.3 and 45.4% for Max-Min values respectively), which in practical terms represents valuable information to detect areas of crop stress, salinity, differential infiltration, responses to water management at field scale, problems with lack of uniformity in water and fertilizer applications, among others.

The research team is working on a report for 2015 season to be released during the summer of 2016. A final report including 2016 season will be released during Spring of 2017.

Project Documents

California Fourth Climate Change Assessment

Economic and Environmental Implications of California Crop and Livestock Adaptations to Climate Change and Climate Policy

To more accurately estimate the threat posed by sea level rise and intense storms to coastal infrastructure, this research will provide assess coastal flood risk accounting for changing climate patterns, erosion rates, shifting beach forms, and vertical land movement. Methods will be developed to support site-specific, project level assessments of coastal vulnerabilities to sea level rise through integration of models of projected sea level rise and climate scenarios, coupled with local and regional-scale erosion rates and vertical land motion estimates.

Collaborators: Daniel A. Sumner