Urban Level of Flood Protection Criteria

California Department of Water Resources (DWR) | November 12th, 2013

The Urban Level of Flood Protection Criteria was developed in response to requirements from the Central Valley Flood Protection Act of 2008, enacted by Senate Bill (SB) 5

The Urban Level of Flood Protection Criteria was developed in response to requirements from the Central Valley Flood Protection Act of 2008, enacted by Senate Bill (SB) 5 (2007), to strengthen the link between flood management and land use. The California Department of Water Resources (DWR) developed these criteria as a systematic approach to assist affected cities and counties within the Sacramento-San Joaquin Valley in making findings related to an urban level of flood protection before approving certain land-use decisions. In preparing these criteria, DWR used its broad experience and expertise in flood management and planning to address concerns related to flood protection and flood risk management. RELATED CONTENT: Urban Levee Design Criteria

Urban Water Demand in California to 2100: Incorporating Climate Change

Pacific Institute | August 28th, 2012

Climate change will have significant impacts in California not just on water supply, but also on water demand. A new, free tool from the Pacific Institute* helps water

Climate change will have significant impacts in California not just on water supply, but also on water demand. A new, free tool from the Pacific Institute* helps water managers to forecast urban water demand with four global climate change models and compare different possible futures to the year 2100 by altering greenhouse gas emissions, population projections, conservation and efficiency measures, and more. The research shows climate change will cause increased water use in California’s cities and suburbs, even as water supply is expected to diminish. Urban water use – residential plus commercial, industrial, and institutional uses – accounts for over 20% of the water use in California, and up to half of urban water use is outdoors. The new report Urban Water Demand in California to 2100: Incorporating Climate Change describes how warming due to climate change is causing increases in water demand for landscapes, and will continue to drive up future water demand, particularly as more Californians settle in warmer, drier inland areas. The Pacific Institute ran a number of scenarios through 2100. The analysis finds that climate change alone could increase urban water demand in 2100 by 8% percent, or around 1 million acre-feet, under a medium-high greenhouse gas emissions scenario. That is the amount of water needed to satisfy the current household needs of 6.7 million Californians. “A million acre-feet of water is significant, and, of course, climate is not the only driver affecting demand. But factoring levels of climate change into the mix is critical,” said Dr. Juliet Christian-Smith of the Pacific Institute Water Program. “Future water use in California depends on a range of factors – technological, political, and economic – many of which are uncertain, but water utilities still need to plan. We created a flexible modeling tool that allows users to run their own scenarios, comparing how a range of factors in a range of climate change scenarios is likely to affect future patterns of water use in their specific areas.”

Urban Water Management Plan Guidebook

California Department of Water Resources (DWR) | January 30th, 2026

In 1983, the State of California Legislature (Legislature) enacted the Urban Water Management Planning Act (UWMP Act). The UWMP Act requires an urban water supplier (Supp

In 1983, the State of California Legislature (Legislature) enacted the Urban Water Management Planning Act (UWMP Act). The UWMP Act requires an urban water supplier (Supplier) providing water for municipal purposes to more than 3,000 customers or serving more than 3,000 acre-feet annually to adopt an Urban Water Management Plan (UWMP) every five years, demonstrating water supply reliability in normal, single dry, and multiple dry water years. The UWMP Act also requires the California Department of Water Resources (DWR) to report to the Legislature on the status of UWMPs. Appendix A contains copies of the UWMP Act and other sections of the California Water Code relevant to UWMPs. Appendix B shows revisions to the UWMP Act and to Water Code. There have been no requirement changes since 2020; only definitions have been added or updated. 

Urban Water Management Planning Guidebook for Urban Water Suppliers (2015)

California Department of Water Resources (DWR) | March 3rd, 2016

The Guidebook for Urban Water Suppliers (Guidebook) has been developed by Department of Water Resources to assist urban water suppliers in preparing 2015 Urban Water Mana

The Guidebook for Urban Water Suppliers (Guidebook) has been developed by Department of Water Resources to assist urban water suppliers in preparing 2015 Urban Water Management Plans (UWMPs or Plans). This guidance is intended to ensure the Plans will address the requirements of the California Water Code (CWC), provide useful information to the public about water suppliers and their water management programs, and provide a framework for water planning to minimize the negative effects of potential water shortages. Water suppliers need not limit themselves to the requirements and recommendations found in the Guidebook. Suppliers may include any additional information that will assist in providing a full description of their water resources and water management.

Urban Water Revolution: Sustainable Water Futures for California Cities

American Society of Civil Engineers (ASCE) | July 15th, 2020

California has consistently altered natural water resources to provide water for its growing population and to support the fifth largest economy in the world. However, th

California has consistently altered natural water resources to provide water for its growing population and to support the fifth largest economy in the world. However, the old ways of coping with the California’s urban water needs—overdraft of groundwater, stream depletion, and greater imports—will no longer meet the demands of the 21st century. We examine California’s water history and present several promising solutions to the challenge of urban water security: a combination of conservation and efficiency, desalination, stormwater capture, water re-use, and water banking. These options for urban water, including direct potable reuse, will help dry cities in California and elsewhere achieve more sustainable and diversified water supply portfolios. Pilot and demonstration-scale projects, along with innovations in systems management and new regulations, point the way toward more resilient water supplies for dry cities. Movement toward regional collaboration, implementation of new technologies, and new regulatory regimes are helping to realize a one-water vision. Different cities will develop their own water supply portfolio options appropriate for their geography, values, and urban form on a path toward meeting the urban water challenges of this century.

Urban Water Use Efficiency (Resource Management Strategy)

California Department of Water Resources (DWR) | July 29th, 2016

During the past few decades, Californians have made great progress in urban water use efficiency. Once viewed and invoked primarily as a temporary strategy in response to

During the past few decades, Californians have made great progress in urban water use efficiency. Once viewed and invoked primarily as a temporary strategy in response to a drought or emergency water shortage situation, water use efficiency has become a permanent part of the long-term management of California’s water supply. At the individual level, the benefits of water use efficiency may appear small, incremental, or difficult to see, but when Californians act together as a community to conserve water, the cumulative effect is significant, and the benefits are widespread. There are several factors that have contributed to increased water use efficiency: outreach efforts that have increased awareness and changed behaviors; urban water suppliers’ implementation of demand management measures (DMMs); plumbing codes requiring more efficient fixtures; the Model Water Efficient Landscape Ordinance (MWELO); advances in irrigation technology; new technologies in the commercial, institutional, and industrial (CII) sectors; and mandates requiring that unmetered connections become metered. But, with tighter environmental constraints on the Sacramento-San Joaquin River Delta (Delta), increasing population, and the necessity of adapting to climate change, even greater efficiencies will be needed and are achievable. When faced with an increasing demand for water, water agencies can consider options for increasing supplies or reducing demand, or a combination of both, to meet this need. Increasing water supply can be expensive and can include costs of purchasing additional water, capital cost of production and distribution systems, water supply treatment facilities, energy costs, and wastewater treatment facilities. Reducing demand through increased water use efficiency is generally lower cost and quicker to implement.

User Manual for the California Central Valley Groundwater-Surface Water Simulation Model

California Department of Water Resources (DWR) | June 13th, 2013

This report describes the input and output files for the California Central Valley Groundwater-Surface Water Simulation Model (C2VSim). C2VSim is an integrated numeri

This report describes the input and output files for the California Central Valley Groundwater-Surface Water Simulation Model (C2VSim). C2VSim is an integrated numerical model simulating land surface processes and groundwater and surface water flows in the main alluvial aquifer system of California’s Central Valley (figure 1). C2VSim was developed using the Integrated Water Flow Model (IWFM) application, which couples a three-dimensional finite element groundwater simulation process with one-dimensional land surface, stream flow, lake, unsaturated zone and smallstream watershed simulation processes. The C2VSim version described in this report runs under IWFM version 3.02 and utilizes a coarse grid, and is thus referred to as version 3.02-CG. In addition, the input files for the C2VSim model are regularly updated to correct errors, incorporate improved input data or extend the simulation time period. These updates are referred to as revisions; this report describes the data in revision R374, released in June 2013. The C2VSim model inputs include monthly historical precipitation, stream inflows, surface water diversions, land use and crop acreages for the simulation period, October 1921 through September 2009. C2VSim dynamically calculates crop water demands, allocates contributions from precipitation, soil moisture and surface water diversions, and calculates the groundwater pumpage required to meet the remaining demand. The coarse grid version of the C2VSim model incorporates a finite element grid with 1392 elements, grouped into 21 water budget subregions (figure 1), which are further grouped by drainage basin into five hydrologic regions. The model subregions are based on Depletion Study Areas (DSAs), originally created by the DWR Division of Planning for estimating regional water supplies and demands. Hydrologic parameters (including hydraulic conductivities, storage parameters and recession coefficients) were calibrated to match observed values including groundwater heads, groundwater head differences between well pairs, surface water flows, and stream-groundwater flows for the period between September 1975 and October 2003. The model simulates the historical response of the Central Valley’s groundwater flow system to historical stresses, and can also be used to simulate the response to projected future stresses. Agricultural groundwater pumping is not monitored in the Central Valley, and the C2VSim model provides pumpage estimates that are considered robust because they are constrained spatially and temporally by the estimated demand and surface water supplies. The calibrated model is also being used as the basis for the groundwater flow component of CalSim 3, a water resources planning model for simulating operation of the California State Water Project (SWP) and Federal Central Valley Project (CVP).

User’s Manual for the Draper Climate-Distribution Software Suite with Data-Evaluation Tools

U.S. Geological Survey (USGS) | March 20th, 2019

Development of a time series of spatially distributed climate data is an important step in the process of developing physically based environmental models requiri

Development of a time series of spatially distributed climate data is an important step in the process of developing physically based environmental models requiring distributed inputs of climate data beyond what is available from observations collected at climate stations. To prepare inputs required for model-mapping units across the study area, climate data (temperature and precipitation) are distributed by combining data from gridded surfaces of mean-monthly climate-data values with (often) widely spaced daily pointobservations. Examples of climate-data files used to develop PRMS-formatted input files for the Merced River Basin Precipitation-Runoff Modeling System (PRMS) are includedin this manual. The Draper Climate-Distribution Software Suite (Draper Suite) consists of the Draper climate-distribution program (Draper) and several supporting pre- and post-processing applications. Draper combines spatially distributed input in the form of monthly averaged values for precipitation, maximum temperature, and minimum temperature with daily observed data from climate stations to estimate distributed climate-data values at predefined locations across a study area (typically adrainage basin) on a daily time step. Alternative methods are used when station data are limited or missing for a particular day. Draper uses a set of required and optional input andoutput files with defined formats and naming conventions. Ashell application also is available to manage multiple runs of the Draper application. Other applications in the Draper Suite include (1) a toolto find and interactively remove outliers in the input data, (2) atool to check and enforce a minimum daily temperature range, and (3) a tool to view output diagnostic information as time- series graphs. These tools can be used iteratively to evaluate and improve the results from Draper as part of a work flow involving physically-based environmental models, such as the Precipitation-Runoff Modeling System (PRMS).

Using Landsat and MODIS satellite collections to examine extent, timing, and potential impacts of surface water inundation in California croplands

Remote Sensing Applications: Society and Environment (RSASE) | October 1st, 2022

The state of California, United States of America produces many crop products that are both utilized domestically and exported throughout the world. With nearly 39,000 km

The state of California, United States of America produces many crop products that are both utilized domestically and exported throughout the world. With nearly 39,000 km2 of croplands, monitoring unintentional and intentional surface water inundation is important for water resource management and flood hazard readiness. We examine inundation dynamics in California croplands from 2003 to 2020 by intersecting monthly surface water maps (n = 216 months) derived using two satellite remote sensing platforms (Landsat and Moderate Resolution Imaging Spectroradiometer [MODIS]) with a high-quality cropland map generated by the California Department of Water Resources. Surface water maps were produced using the Dynamic Surface Water Extent model, in which satellite image pixels are classified into different levels of detection confidence. Our analysis focused on calculating monthly and annual occurrence of “high confidence” water for each satellite collection across eight cropland types and 58 counties. Results indicate that 49.9% (MODIS) to 56.4% (Landsat) of croplands were inundated at least once during the 18-year timespan. Rice crops, due to their unique need of consistent surface water and dominance as a crop type in CA, had the highest proportion of and mean annual inundation area, while citrus crops had the lowest. Mean monthly inundation patterns in most croplands followed California's precipitation patterns with high inundation during the winter and spring rainy season. At the county level, croplands in the southern Central Valley typically had high occurrences of inundation in conjunction with large crop areas. Exposure and sensitivity of inundation for three crop types (citrus, deciduous, and vineyards) that are typically less associated with intentional inundation were geographically variable, but overall were generally highest in counties in the southern Central Valley, California's primary agricultural region. Flood and precipitation related crop insurance claims indicated that rice had the highest mean indemnity payout for any month with damages typically occurring in March and April. Insurance claims were also high in deciduous fruit and nut crops, which had peak damages in February. A comparison between inundation results and insurance claims suggests that the inundation mapped by our process coincides with claim activity. These data elucidate water inundation patterns across the state that can serve to inform farmers, insurers, decision makers, resource managers, and flood mitigation professionals.

Utah's Land, Water and Air 2022 Report to the Governor

Utah State University | November 30th, 2022