California Simulation of Evapotranspiration of Applied Water and Agricultural Energy Use in California

Journal of Integrative Agriculture (Elsevier) | August 5th, 2013

The California Simulation of Evapotranspiration of Applied Water (Cal-SIMETAW) model is a new tool developed by the California Department of Water Resources and t

The California Simulation of Evapotranspiration of Applied Water (Cal-SIMETAW) model is a new tool developed by the California Department of Water Resources and the University of California, Davis to perform daily soil water balance and determine crop evapotranspiration (ETc), evapotranspiration of applied water (ETaw), and applied water (AW) for use in California water resources planning. ETaw is a seasonal estimate of the water needed to irrigate a crop assuming 100% irrigation efficiency. The model accounts for soils, crop coefficients, rooting depths, seepage, etc. that influence crop water balance. It provides spatial soil and climate information and it uses historical crop and land-use category information to provide seasonal water balance estimates by combinations of detailed analysis unit and county (DAU/County) over California. The result is a large data base of ETc and ETaw that will be used to update information in the new California Water Plan (CWP). The application uses the daily climate data, i.e., maximum (Tx) and minimum (Tn) temperature and precipitation (Pcp), which were derived from monthly USDA-NRCS PRISM data (PRISM Group 2011) and daily US National Climate Data Center (NCDC) climate station data to cover California on a 4 km×4 km change grid spacing. The application uses daily weather data to determine reference evapotranspiration (ETo), using the Hargreaves-Samani (HS) equation (Hargreaves and Samani 1982, 1985). Because the HS equation is based on temperature only, ETo from the HS equation were compared with CIMIS ETo at the same locations using available CIMIS data to determine correction factors to estimate CIMIS ETo from the HS ETo to account for spatial climate differences. Cal-SIMETAW also employs near real-time reference evapotranspiration (ETo) information from Spatial CIMIS, which is a model that combines weather station data and remote sensing to provide a grid of ETo information. A second database containing the available soil water holding capacity and soil depth information for all of California was also developed from the USDA-NRCS SSURGO database. The Cal-SIMETAW program also has the ability to generate daily weather data from monthly mean values for use in studying climate change scenarios and their possible impacts on water demand in the state. The key objective of this project is to improve the accuracy of water use estimates for the California Water Plan (CWP), which provides a comprehensive report on water supply, demand, and management in California. In this paper, we will discuss the model and how it determines ETaw for use in water resources planning.

California's Water – Energy Relationship

California Energy Commission (CEC) | November 1st, 2005

This is an urgent time of both challenge and opportunity. The primary finding of this paper is that a major portion of the solution is closer coordination between the wat

This is an urgent time of both challenge and opportunity. The primary finding of this paper is that a major portion of the solution is closer coordination between the water and energy sectors. A meaningful solution cannot be reached in the current regulatory environment where water utilities value only the cost of acquisition, conveyance, treatment, and delivery; wastewater utilities value only the cost of collection, treatment, and disposal; electric utilities value only saved electricity; and natural gas utilities value only saved natural gas. The state must both develop and expand best practices and existing programs to realize the substantial incremental benefits of joint water and energy resources and infrastructure management. While many nuances of this complex statewide problem are still unclear, staff’s analysis shows that significant energy benefits can be reaped through the twin goals of the efficient use of water by end users and the efficient use of energy by water systems. It is also clear that not nearly enough has been done to ensure that California’s water supply strategies are synchronized, hand-in-hand, with its energy strategies. Nor has enough been done to forge partnerships between the water and energy sectors so that their natural synergies, joint resources, and assets can be effectively leveraged for the benefit of all Californians. The state has the opportunity now to reap near-term energy benefits by helping California’s water and wastewater utilities become more energy self-sufficient, which will ease pressures on California’s already stressed electric system. By adjusting existing policies, programs, and resources, water and wastewater utilities could be converted from high energy users to net renewable energy producers. California’s water and energy policymakers need to commit today to the joint planning and management of these critical resources. The state’s water plan and resource strategies are being reviewed with all key stakeholders, and implementation plans are already on the drawing table. At the same time, the California Public Utilities Commission has approved substantial utility ratepayer expenditures in energy efficiency programs for the 2006-2008 program cycle. The state must waste no time in taking advantage of these rapidly evolving events. The state can meet energy and demand-reduction goals comparable to those already planned by the state’s investor-owned energy utilities for the 2006-2008 program period by simply recognizing the value of the energy saved for each unit of water saved. If allowed to invest in these cold water energy savings, energy utilities could co-invest in water use efficiency programs, which would in turn supplement water utilities’ efforts to meet as much load growth as possible through water efficiency. Remarkably, staff’s initial assessment indicates that this benefit could be realized at less than half the cost to electric ratepayers of traditional energy efficiency measures. This staff report examines how energy is used – and how it can be saved – in the water use cycle. The strategies and goals for a comprehensive statewide water-energy program would achieve incremental energy benefits for water and energy utilities. The overarching goal of establishing a comprehensive statewide water-energy program would create a dynamic, living process where key stakeholders have incentives to continuously identify and implement strategies optimizing the state’s water and energy resources and assets on an integrated, coordinated, and collaborative basis. This opportunity must not be lost since the need is so great. Because of all these factors, staff recommends that an action-oriented approach structured to achieve near-term results be developed immediately.

California's Water–Energy Relationship

California Energy Commission (CEC) | November 1st, 2005

This report examines the dynamic give-and-take relationship between California’s water and energy resources. Among many other issues, this staff report examines the s

This report examines the dynamic give-and-take relationship between California’s water and energy resources. Among many other issues, this staff report examines the state’s water sector and its energy use, along with changes likely to occur in the future.

California’s Water: Energy and Water

Public Policy Institute of California (PPIC) | October 1st, 2016

Energy and water use in the state are interconnected yet managed separately. This brief describes the synergies and tradeoffs between the two sectors and proposes way

Energy and water use in the state are interconnected yet managed separately. This brief describes the synergies and tradeoffs between the two sectors and proposes ways to increase the efficiency and sustainability of both. This publication is part of a briefing kit that summarizes a dozen of the state’s most pressing water management issues.

Carbon Footprint Planning: Quantifying Local and State Mitigation Opportunities for 700 California Cities

Urban Planning (Cogitatio) | April 17th, 2018

Consumption-based greenhouse gas (GHG) emissions inventories have emerged to describe full life cycle contributions of households to climate change at country, st

Consumption-based greenhouse gas (GHG) emissions inventories have emerged to describe full life cycle contributions of households to climate change at country, state and increasingly city scales. Using this approach, how much carbon foot- print abatement potential is within the control of local governments, and which policies hold the most potential to reduce emissions? This study quantifies the potential of local policies and programs to meet aggressive GHG reduction targets using a consumption-based, high geospatial resolution planning model for the state of California. We find that roughly 35% of all carbon footprint abatement potential statewide is from activities at least partially within the control of local governments. The study shows large variation in the size and composition of carbon footprints and abatement opportu- nities by ∼23,000 Census block groups (i.e., neighborhood-scale within cities), 717 cities and 58 counties across the state. These data and companion online tools can help cities better understand priorities to reduce GHGs from a comprehensive, consumption-based perspective, with potential application to the full United States and internationally.

Central Valley Basin: A Comprehensive Report on the Development of the Water and Related Resources of the Central Valley Basin for Irrigation, Power Production and Other Beneficial Uses in California, and Comments by the State of California and Federal Agencies

U.S. Bureau of Reclamation (USBR) | August 15th, 1949

Climate Action Plan Phase 1 Greenhouse Gas Emissions Reduction Plan Update 2023

California Department of Water Resources (DWR) | March 22nd, 2024

DWR developed the Greenhouse Gas Emissions Reduction Plan Update 2023 (Update 2023) to review its GHG reductions since Update 2020 and to update strategies for further re

DWR developed the Greenhouse Gas Emissions Reduction Plan Update 2023 (Update 2023) to review its GHG reductions since Update 2020 and to update strategies for further reduction consistent with legislative changes, including the GHG emissions reduction targets established in SB 1020 (2022) and SB 1203 (2022). It also includes DWR’s new role in emergency energy generation. Since the 2012 Plan was adopted, California’s wholesale electricity market has also seen a significant increase in renewable resources. To reflect this change and to align with industry practice in emission reporting, Update 2023 incorporates updated emission factors to determine emissions from unspecified market resources.

Climate Action Plan Phase 1: Greenhouse Gas Emissions Reduction Plan

California Department of Water Resources (DWR) | May 18th, 2012

The California Department of Water Resources (DWR) in an effort to reduce its impact on the environment and lead by example, has developed this Greenhouse Gas (GHG) Emiss

The California Department of Water Resources (DWR) in an effort to reduce its impact on the environment and lead by example, has developed this Greenhouse Gas (GHG) Emissions Reduction Plan to guide its project development and decision making with respect to energy use and GHG emissions. It is now clearly understood that these gases enhance the Earth’s ability to absorb and retain the heat radiated from the sun. Increased concentrations of GHGs in the atmosphere are the principal cause of anthropogenic climate change. As the connection between GHG emissions and climate change has strengthened and California has established GHG policies and reduction goals, DWR has focused on its own GHG emissions and developed strategies to reduce its contribution to the global problem of climate change consistent with those policies and goals. This GHG Emissions Reduction Plan (Plan) is the first Phase in DWR’s Climate Action Plan and considers GHG emissions from all DWR activities. In this Plan, DWR details its progress and future plans for reducing GHG emissions consistent with the GHG emissions reduction targets established in Assembly Bill (AB) 32, Executive Order S-3-05, and DWR’s own policies, the aggressive steps it will take to reduce its emissions by over 80% below 1990 levels, and the steps that it will take to monitor its progress toward achieving these reductions. DWR estimates that its total GHG emissions in 1990 were nearly 3.5 million metric tons, roughly the equivalent of a coal fired power plant or 680,000 passenger cars. Most of these emissions were released as a result of generation of electricity used to move water through the State Water Project (SWP), which DWR owns and operates. Since 1990, DWR’s GHG emissions have fluctuated due to hydrologic conditions, water demands, and energy resources. DWR GHG emissions peaked in 2003 at over 4.1 million metric tons per year. This Plan shows how DWR will make substantial reductions in its GHG emissions in the near-term (present to 2020) and how it will continue to reduce emissions beyond 2020 to achieve its long-term (2050) GHG emissions reduction goals.

Climate change and its influence on water systems increases the cost of electricity system decarbonization

Nature Portfolio (Springer Nature) | November 25th, 2024

Climate Change Effects on the High-Elevation Hydropower System with Consideration of Warming Impacts on Electricity Demand and Pricing

California Energy Commission (CEC) | July 31st, 2012

While only about 30 percent of California’s usable water storage capacity lies at higher elevations, high-elevation hydropower units generate, on average, 74 percent of

While only about 30 percent of California’s usable water storage capacity lies at higher elevations, high-elevation hydropower units generate, on average, 74 percent of California’s instate hydroelectricity. In general, high-elevation plants have small man-made reservoirs and rely mainly on snowpack. Their low built-in storage capacity is a concern with regard to climate warming. Snowmelt is expected to shift to earlier in the year, and the system may not be able to store sufficient water for release in high-demand periods. Previous studies have explored the climate warming effects on California’s high-elevation hydropower system by focusing on the supply side (exploring the effects of hydrological changes on generation and revenues) but they have ignored the warming effects on hydropower demand and pricing. This study extends the previous work by simultaneous consideration of climate change effects on high-elevation hydropower supply and demand in California. Artificial Neural Network models were developed as long-term price estimation tools, to investigate the impact of climate warming on energy prices. California’s Energy-Based Hydropower Optimization Model (EBHOM) was then applied, to estimate the adaptability of California’s high-elevation hydropower system to climate warming, considering the warming effects on hydropower supply and demand. The model was run for dry and wet warming scenarios, representing a range of hydrological changes under climate change. The model’s results relative to energy generation, energy spills, reservoir energy storage, and average shadow prices of energy generation and storage capacity expansion are examined and discussed. The modeling results are compared with previous studies to emphasize the need to consider climate change effects on hydroelectricity demand and pricing when exploring the effects of climate change on California’s hydropower system.