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

Project Contact: