Flexibility and intensity of global water use

Nature Portfolio (Springer Nature) | June 3rd, 2019

Water stress is often evaluated by scarcity: the share of available water supply being consumed by humans. However, some consumptive uses of water are more or less flexib

Water stress is often evaluated by scarcity: the share of available water supply being consumed by humans. However, some consumptive uses of water are more or less flexible than others, depending on the costs or effects associated with their curtailment. Here, we estimate the share of global water consumption over the period 1980–2016 from the relatively inflexible demands of irrigating perennial crops, cooling thermal power plants, storing water in reservoirs and supplying basic water for humans and livestock. We then construct a water stress index that integrates the share of runoff being consumed (scarcity), the share of consumption in these inflexible categories (flexibility) and the historical variability of runoff weighted by storage capacity (variability), and use our index to evaluate the trends in water stress of global major river basins on six continents. We find that the 10% most stressed basins encompass ~19%, 19% and 35% of global population, thermal electricity generation and irrigated calorie production, respectively, and some of these basins also experience the largest increases in our identified stress indexes over the study period. Water consumption intensities (water used per unit of goods or service produced) vary by orders of magnitude across and within continents, with highly stressed basins in some cases characterized by high water consumption intensities. Our results thus point to targeted water mitigation opportunities (for example, relocating crops and switching cooling technologies) for highly stressed basins.

Flood Size Increases Nonlinearly Across the Western United States in Response to Lower Snow-Precipitation Ratios

American Geophysical Union (AGU) | December 20th, 2019

Many mountainous and high-latitude regions have experienced more precipitation as rain rather than snow due to warmer winter temperatures. Further decreases in the annual

Many mountainous and high-latitude regions have experienced more precipitation as rain rather than snow due to warmer winter temperatures. Further decreases in the annual snow fraction are projected under continued global warming, with potential impacts on flood risk. Here, we quantify the size of streamflow peaks in response to both seasonal and event-specific rain-fraction using stream gage observations from watersheds across the western United States. Across the study watersheds, the largest rainfall-driven streamflow peaks are >2.5 times the size of the largest snowmelt-driven peaks. Using a panel regression analysis of individual precipitation and snowmelt events, we show that the empirical streamflow response grows approximately exponentially as the liquid precipitation input increases, with rain-dominated runoff leading to proportionately larger streamflow increases than snowmelt or mixed rain-and-snow runoff. We find that the response to changes in rain percentage is largest in the wettest watersheds, where wet antecedent conditions are important for increasing runoff efficiency. Similarly, the effect of rain percentage is larger across watersheds in the Northwest and West regions compared to watersheds in the Northern Rockies and Southwest regions. Overall, as a higher percentage of precipitation falls as rain, increases in the size of rainfall-driven and “rain-on-snow”-driven floods have the potential to more than offset decreases in the size of snowmelt-driven floods.

Fourth Five Year Review Report for the San Gabriel Valley Area 2 Superfund Site, Los Angeles, California

U.S. Environmental Protection Agency (EPA) | September 15th, 2022

This is the fourth Five-Year Review of the San Gabriel Valley Area 2 (Site) located in the San Gabriel Valley in Los Angeles County, California. The purpose of this Five-

This is the fourth Five-Year Review of the San Gabriel Valley Area 2 (Site) located in the San Gabriel Valley in Los Angeles County, California. The purpose of this Five-Year Review is to review information to determine if the remedy is and will continue to be protective of human health and the environment. The Site addresses approximately 10 square miles of groundwater contamination in eastern Los Angeles County within the San Gabriel Valley. Groundwater contamination is believed to result from the cumulative impact of decades of improper chemical handling and disposal practices at numerous industrial operations in the Valley. The Site contamination originates at current and former industrial facilities in and near Azusa, California and extends to the southwest through portions of the cities of Irwindale, Baldwin Park, West Covina, and Industry. The most prevalent contaminants in groundwater are trichloroethylene, tetrachloroethylene, carbon tetrachloride, perchlorate, n-nitrosodimethylamine (NDMA), and 1,4-dioxane.

Fourth Supplement to State Water Resources Board Bulletin No. 11 San Joaquin County Investigation, Basic Data, Calaveras Unit 1957-58

California Department of Water Resources (DWR) | March 27th, 1959

Freshwater Scarcity

Annual Review of Environment and Resources (Annual Reviews) | October 24th, 2021

The availability and use of fresh water are critical for human health and for economic and ecosystem stability. But the growing mismatch between human demands and natur

The availability and use of fresh water are critical for human health and for economic and ecosystem stability. But the growing mismatch between human demands and natural freshwater availability is contributing to water scarcity, affecting industrial and agricultural production and a wide range of social, economic, and political problems, including poverty, deterioration of ecosystem health, and violent conflicts. Understanding and addressing different forms of water scarcity are vital for moving toward more sustainable management and use of fresh water. We provide here a review of concepts and definitions of water scarcity, metrics and indicators used to evaluate scarcity together with strategies for addressing and reducing the adverse consequences of water scarcity, including the development of alternative sources of water, improvements in water-use efficiency, and changes in systems of water management and planning.

Future increase in extreme El Niño supported by past glacial changes

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

Future precipitation increase from very high resolution ensemble downscaling of extreme atmospheric river storms in California

American Association for the Advancement of Science (AAAS) | July 15th, 2020

Precipitation extremes will likely intensify under climate change. However, much uncertainty surrounds intensification of high-magnitude events that are often i

Precipitation extremes will likely intensify under climate change. However, much uncertainty surrounds intensification of high-magnitude events that are often inadequately resolved by global climate models. In this analysis, we develop a framework involving targeted dynamical downscaling of historical and future extreme precipitation events produced by a large ensemble of a global climate model. This framework is applied to extreme “atmospheric river” storms in California. We find a substantial (10 to 40%) increase in total accumulated precipitation, with the largest relative increases in valleys and mountain lee-side areas. We also report even higher and more spatially uniform increases in hourly maximum precipitation intensity, which exceed Clausius- Clapeyron expectations. Up to 85% of this increase arises from thermodynamically driven increases in water vapor, with a smaller contribution by increased zonal wind strength. These findings imply substantial challenges for water and flood management in California, given future increases in intense atmospheric river-induced precipitation extremes.

Geohydrology and Evapotranspiration at Franklin Lake Playa, Inyo County, California

U.S. Geological Survey (USGS) | July 1st, 1997

Geohydrology and Water Chemistry of the Alexander Valley, Sonoma County, California

U.S. Geological Survey (USGS) | January 12th, 2006

This study of the geohydrology and water chemistry of the Alexander Valley, California, was done to provide an improved scientific basis for addressing emerging wate

This study of the geohydrology and water chemistry of the Alexander Valley, California, was done to provide an improved scientific basis for addressing emerging water-management issues, including potential increases in water demand and changes in flows in the Russian River. The study tasks included (1) evaluation of existing geohydrological, geophysi- cal, and geochemical data; (2) collection and analysis of new geohydrologic data, including subsurface lithologic data, ground-water levels, and streamflow records; and (3) collection and analysis of new water-chemistry data. The estimated total water use for the Alexander Valley for 1999 was approximately 15,800 acre-feet. About 13,500 acre-feet of this amount was for agricultural use, primarily vineyards, and about 2,300 acre-feet was for municipal/industrial use. Ground water is the main source of water supply for this area. The main sources of ground water in the Alexander Valley are the Quaternary alluvial deposits, the Glen Ellen Formation, and the Sonoma Volcanics. The alluvial units, where sufficiently thick and saturated, comprise the best aquifer in the study area. Average recharge to the Alexander Valley is estimated from a simple, basinwide water budget. On the basis of an estimated annual average of 298,000 acre-feet of precipitation, 160,000 acre-feet of runoff, and 113,000 to 133,000 acre-feet of evapotranspiration, about 5,000 to 25,000 acre-feet per year is available for ground-water recharge. Because this estimate is based on differences between large numbers, there is significant uncertainty in this recharge estimate. Long-term changes in ground-water levels are evident in parts of the study area, but because of the sparse network and lack of data on well construction and lithology, it is uncertain if any significant changes have occurred in the northern part of the study area since 1980. In the southern half of the study area, ground-water levels generally were lower at the end of the 2002 irrigation season than at the end of the 1980 season, which suggests that a greater amount of ground water is being pumped in the southern half of the study area in recent years compared with that pumped in the early 1980s. Water-chemistry data for samples collected from 11 wells during 2002–04 indicate that water quality in the study area generally is acceptable for potable use. Two wells, however, each contained one constituent (241 μg/L of manganese and 1,350 μg/L of boron) in excess of the recommended standards for drinking water (50 μg/L and 1,000 μg/L, respectively). The chemical composition of water from most of the wells sampled for major ions plot as a mixed cation-bicarbon- ate, magnesium-bicarbonate, or calcium-bicarbonate type water. The ionic composition of the historical and recent samples from wells in the Alexander Valley is similar to that of the historical surface-water samples collected from the Russian River near Healdsburg. This suggests a similar source of water, particularly for wells that are less than 200 feet total depth and perforated in Quaternary alluvial deposits. Water from deeper, non-alluvial wells may contain slightly higher concentrations of sodium as a result of cation exchange. Water samples collected from several wells over an approximately 30–year period suggest a progressive change in water chemistry over time. Samples from the southern part of the valley show a trend towards higher ionic concentrations and increasing concentrations of particular constituents such as sulfate.

Geologic Map and Borehole Stratigraphy of Hinkley Valley and Vicinity, San Bernardino County, California

U.S. Geological Survey (USGS) | December 17th, 2020

Hinkley Valley, in the central to western Mojave Desert of southeastern California, has a long historical record owing to its position as a crossroads for rail and road t

Hinkley Valley, in the central to western Mojave Desert of southeastern California, has a long historical record owing to its position as a crossroads for rail and road traffic and its position adjacent to the Mojave River. Subflow in the Mojave River provided groundwater recharge that maintained water consumption and demand by way of shallow wells for local agriculture (Thompson, 1929) in the valley. Its crossroads position led to construction of several power-transmission lines, pipeline, and communications cable routes that transect Hinkley Valley. One of these, a natural gas pipeline and its associated compressor station, was the locus of hexavalent chromium, Cr(VI), releases into, and consequent contamination of, groundwater (Izbicki and Groover, 2018). Understanding the movement and fate of the contaminants is a complex hydrologic and geo-chemical problem. Geologic mapping of the Hinkley Valley area provides framework elements for use in resolving this problem.