UN-Water Analytical Brief on Unconventional Water Resources

United Nations (UN) | June 5th, 2020

Increasing water scarcity is recognized as a key challenge to sustainable development and major cause of conflict, social unrest and changes to traditional migration rout

Increasing water scarcity is recognized as a key challenge to sustainable development and major cause of conflict, social unrest and changes to traditional migration routes and new migration patterns. At the same time water is increasingly considered as an instrument for international cooperation to support food production, livelihoods, ecosystems, climate change adaption, and sustainable development. As water scarcity is set to continue and intensify in dry areas, the world at large is in danger of leaving the water scarcity challenge to future generations who will be confronted with the consequences of today’s practices. Thus, water-scarce areas must sustainably access and utilize every available option for water resources in order to minimize the pressure that continues to grow. Conventional water provisioning approaches relying on snowfall, rainfall and river runoff are not enough to meet growing freshwater demand in water-scarce areas. Considering the water-related sustainable development challenges in arid regions, unconventional water resources are an emerging opportunity to narrow the water demand-supply gap. There are fragmented, but growing, examples of using unconventional water resources across the world to boost water supplies to address water scarcity.

Uncertainty in El Niño-like warming and California precipitation changes linked by the Interdecadal Pacific Oscillation

Nature Portfolio (Springer Nature) | November 10th, 2021

Marked uncertainty in California (CA) precipitation projections challenges their use in adaptation planning in the region already experiencing severe water stress. Under

Marked uncertainty in California (CA) precipitation projections challenges their use in adaptation planning in the region already experiencing severe water stress. Under global warming, a westerly jet extension in the North Pacific analogous to the El Niño-like teleconnection has been suggested as a key mechanism for CA winter precipitation changes. However, this teleconnection has not been reconciled with the well-known El Niño-like warming response or the controversial role of internal variability in the precipitation uncertainty. Here we find that internal variability contributes > 70% and > 50% of uncertainty in the CA precipitation changes and the El Niño-like warming, respectively, based on analysis of 318 climate simulations from several multi-model and large ensembles. The Interdecadal Pacific Oscillation plays a key role in each contribution and in connecting the two via the westerly jet extension. This unifying understanding of the role of internal variability in CA precipitation provides critical guidance for reducing and communicating uncertainty to inform adaptation planning.

Understanding the Contributions of Paleo-Informed Natural Variability and Climate Changes to Hydroclimate Extremes in the San Joaquin Valley of California

American Geophysical Union (AGU) | November 13th, 2023

Understanding the recent increase in multiyear La Niñas

Nature Portfolio (Springer Nature) | September 18th, 2023

Untapped Potential: An Assessment of Urban Stormwater Runoff Potential in the United States

Pacific Institute | February 29th, 2024

In this assessment, we quantify the volumetric potential for stormwater runoff in US Census Urban Areas across the entire United States. This assessment finds that the av

In this assessment, we quantify the volumetric potential for stormwater runoff in US Census Urban Areas across the entire United States. This assessment finds that the average annual volumetric potential for urban stormwater runoff is 59.5 million acre-feet per year (AFY), or 53,100 million gallons per day (MGD). This volume is equivalent to 93% of the water withdrawals for municipal and industrial uses in 2015, though not all of this runoff is necessarily feasible or desirable to capture. We estimate that 37% of this national volume (21.9 million AFY) is generated just in coastal areas, which presents an opportunity for increased stormwater capture in areas that are less likely to face challenges related to adverse impacts on downstream water rights holders.

Updated Groundwater Sustainability Plan, San Joaquin Valley – Tule, Alpaugh Groundwater Sustainability Agency

Alpaugh Groundwater Sustainability Agency | July 27th, 2022

Alpaugh GSA is part of the Tule Subbasin and was formed in May 2016 for the purpose of complying with the SGMA. This updated GSP complies with the SGMA by addressing the

Alpaugh GSA is part of the Tule Subbasin and was formed in May 2016 for the purpose of complying with the SGMA. This updated GSP complies with the SGMA by addressing the DWR GSP Emergency Regulations in § 354.2 through 354.10. The GSP is the result of a collaborative process between local water agencies, technical experts, environmental managers, and community members with a mutual goal of sustainably managing the groundwater basin. Alpaugh GSA is one of seven participating GSAs in the Tule Subbasin, which organize their activities through the updated Tule Subbasin Coordination Agreement (Coordination Agreement). Due to size this file has been divided. Part 1, Part 2, Part 3, Part 4, Part 5

Updating the CALVIN Hydro-Economic Optimization Model of California: Central Valley Groundwater

University of California, Davis (UC Davis) | July 11th, 2012

Updates are being made to Central Valley groundwater in CALVIN, a hydro-economic model of California’s intertied water supply and delivery system. These updates reflect

Updates are being made to Central Valley groundwater in CALVIN, a hydro-economic model of California’s intertied water supply and delivery system. These updates reflect better estimates of water demands, groundwater availability, and local water management opportunities. This poster focuses on updating CALVIN groundwater parameters based on California Department of Water Resources’ (DWR) California Central Valley Groundwater-Surface Water Simulation Model (C2VSIM) and the United States Geological Survey (USGS) Central Valley Hydrologic Model (CVHM) model inputs and results. Two CALVIN update projects, using the DWR and USGS groundwater models, are underway to improve groundwater representation including basin inflows, reuse, return flows, capacities, and pumping costs. These sub-projects will result in a CALVIN model with updated groundwater representation based on C2VSIM and CVHM. This poster shows a preliminary comparison of these sub-projects and a summary comparison between the DWR and USGS models.

Urban and Agricultural Water Use in California, 1960–2015

Pacific Institute | June 22nd, 2020

Water is the lifeblood of California. It provides for the household needs of 40 million people. It generates electricity and cools power plants. It supports one of the mo

Water is the lifeblood of California. It provides for the household needs of 40 million people. It generates electricity and cools power plants. It supports one of the most productive agricultural regions in the world and various commercial and industrial activities, ultimately fueling the fifth largest economy in the world. Water is also critical to the health and viability of the state’s diverse aquatic and terrestrial ecosystems. This paper examines statewide urban and agricultural water-use trends from 1960 to 2015 using data from the California Department of Water Resources (DWR). We find that California has experienced a dramatic decoupling between water use and growth. Since 1967, California’s population has doubled, and its economic output has increased by a factor of five. Yet statewide water use increased by only 20 percent over this period due to improvements in urban and agricultural efficiency, as well as a shift to higher-value crops and less water-intensive commercial and industrial activities.  Despite positive signs, water use in California remains high. Across the state, rivers and streams are under stress from overuse, and groundwater is over-tapped. Climate change and continued growth are increasing pressure on the state’s water resources, including on water supply, demand, and quality. To address these challenges, we must continue and even expand efforts to improve the water-use efficiency of our homes, businesses, industries, and farms. Moreover, we urge the state to improve data collection and online systems to make data more easily, quickly, and readily available.

Urban hydrology and water management— Present and future challenges

Urban Water (Elsevier) | March 1st, 1999

Urban hydrology is an applied science that will have an increasing role to play in the sustainability of human societies. Facing present growth of urban population, it is

Urban hydrology is an applied science that will have an increasing role to play in the sustainability of human societies. Facing present growth of urban population, it is increasingly difficult to find and utilize new sources of water necessary to satisfy growing water demand. For the poor, the residents of peri-urban and squatter areas, an ultimate poverty, the poverty of lacking clean water, is a result. To remove this kind of poverty should be a first priority target for all people and, especially, for people dealing with water management in urban areas. Growth of urban areas brings significant changes in physical properties of land surface increasing integrated vulnerability of inhabitants, agricultural land and rural ecological life supporting systems. Performance of technical solutions depends on climate as well as on social, economical and cultural conditions. Findings from urban hydrological studies based on collection of urban hydrological data, calculations and modeling constitute a necessary fundamental for meaningful water management not only in urban areas but also in entire river basins. Future challenges in urban water management include development of new technical solutions as well as logistic and organizational methods in order to turn present problems into future opportunities. The following current and emerging challenges are discussed in the paper: delivery of drinking water supply for growing cities, water for sanitation versus sanitation without water, recycling of wastewater nutrients, wastewater irrigation, urban agriculture, water to feed depleted aquifers, thoughts about possible future new system solutions, social equity and transfer of knowledge and new technology.

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.”