For more information on the USGS-the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment-visit https://www.usgs.gov or call 1-888-ASK-USGS. For an overview of USGS information products, including maps, imagery, and publications, visit https://www.store.usgs.gov. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner.

Abstract:The current accelerated growth in demand for energy globally is confronted by water-resource limitations and hydrologic variability linked to climate change. The global spatial and temporal trends in water requirements for energy development and policy alternatives to address these constraints are poorly understood. This article analyzes national-level energy demand trends from U.S. Energy Information Administration data in relation to newly available assessments of water consumption and life-cycle impacts of thermoelectric generation and biofuel production, and freshwater availability and sectoral allocations from the U.N. Food and Agriculture Organization and the World Bank. Emerging, energy-related water scarcity flashpoints include the world's largest, most diversified economies (Brazil, India, China, and USA among others), while physical water scarcity continues to pose limits to energy development in the Middle East and small-island states. Findings include the following: (a) technological obstacles to alleviate water scarcity driven by energy demand are surmountable; (b) resource conservation is inevitable, driven by financial limitations and efficiency gains; and (c) institutional arrangements play a pivotal role in the virtuous water-energy-climate cycle. We conclude by making reference to coupled energy-water policy alternatives including water-conserving energy portfolios, intersectoral water transfers, virtual water for energy, hydropower tradeoffs, and use of impaired waters for energy development. OPEN ACCESSEnergies 2015, 8 8212

Mapping the expansion of impervious surfaces in urbanizing areas is important for monitoring and understanding the hydrologic impacts of land development. The most common approach using spectral vegetation indices, however, is difficult in arid and semiarid environments where vegetation is sparse and often senescent. In this study object-oriented classification of high-resolution imagery was used to develop a cost-effective, semi-automated approach for mapping impervious surfaces in Sierra Vista, Arizona for an individual neighborhood and the larger sub-watershed. Results from the neighborhood-scale analysis show that object-oriented classification of QuickBird imagery produced repeatable results with good accuracy. Applying the approach to a 1,179 km 2 region produced maps of impervious surfaces with a mean overall accuracy of 88.1 percent. This study demonstrates the value of employing object-oriented classification of high-resolution imagery to operationally monitor urban growth in arid lands at different spatial scales in order to fill knowledge gaps critical to effective watershed management.

[1] Observations of the temporal and spatial distribution of poststorm soil moisture in open shrublands and savannas are limited, yet they are critical to understanding the interaction and feedback between moisture distribution and canopies. The objective of this analysis was to study the hydrologic impacts of precipitation pulses on the upper layer of soils under and between shrubs. The study was based on measurements of precipitation, runoff, and under-and between-shrub soil moisture over a period of 20 years (1990)(1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)) at a shrubdominated site in the Walnut Gulch Experimental Watershed (WGEW) near Tombstone, Arizona. Within much of the root zone (to 30 cm depth), infiltration was not significantly different under versus between shrubs, and the under:between infiltration ratio was not related to pulse size or intensity. However, root-zone soil moisture was significantly higher between shrubs than under shrubs. The soil moisture measured at the surface (at 5 cm depth) was not consistently different under and between shrubs, but the soil moisture measured at depths of 15 and 30 cm were both significantly higher between shrubs than under shrubs. Considering mechanisms that explain the interaction between plants and soil moisture, we found no differences in infiltration, evaporative losses, and surface soil moisture in locations under and between shrubs. This led to the conclusion that lower root-zone soil moisture under shrubs was due largely to greater root density under shrubs than between shrubs. This study adds to the understanding of the impact of precipitation patterns on infiltration and soil moisture in shrub-dominated sites and the potential for vegetation change in arid and semiarid lands.

To understand transboundary groundwater governance in the South American Guarani Aquifer System, we surveyed global and regional experts about the region's groundwater quantity and quality, ownership and rights, and regulation and administration. Respondents (1) perceived groundwater quality and withdrawal as under-regulated, and relevant information and data as inadequate;(2) suggested that contamination and overdrafting remain mostly incipient and localized along international borders; and (3) viewed groundwater as a shared resource administered by the state for the public, rather than as private property. Respondents suggested that while there is progress towards implementing a formal transboundary aquifer agreement, local-to-nationalscale governance is important.

Abstract:Entrenched Western water rights regimes may appear to function relatively well in wet years, but extreme drought events can expose the kinds of harsh ecological and socio-economic outcomes that the hard edges of prior appropriation inherently generate. During the 2012-2016 California drought some irrigators received little or no water at all in consecutive years while others received comparatively large allocations. This paper focuses on the role that California's water rights priority system and its administration via Central Valley Project contracts have played in generating disproportionate water allocations and impacts during the drought. The analysis is structured around two key questions: (a) in what ways does strict adherence to a priority system of water allocations produce inequitable socio-ecological outcomes during severe drought? (b) how might the system be changed to foster outcomes that are more equitable and fair, and with less costly and less serious conflicts in a non-stationary climate future marked by extreme events? Using an equity perspective, I draw from the doctrine of equitable apportionment to imagine a water rights regime that is better able to create a fairer distribution of drought impacts while meaningfully elevating the importance of future generations and increasing adaptive capacity.

No abstract

Although the proliferation of open water data platforms and initiatives in recent years is a laudable phenomenon, there is little empirical evidence indicating whether and to what extent these efforts are generating anticipated benefits of improved transparency, citizen participation, innovation, and water resource decision making. Relatedly, water resource researchers have devoted little attention to identifying and accounting for barriers that may be limiting open water data efforts from realizing their potential. The premise of this overview is that (a) open water data efforts could be improved with a better understanding of the non‐technical challenges and that (b) water researchers interested in open water data would benefit from delving into the emerging body of research in public policy, information science, and other disciplines on open data barriers more broadly. However, the research on open data barriers has neglected water sustainability issues. In light of this asymmetry, the aim of this overview is to foster interdisciplinary engagement on this topic by introducing the water resource community to this literature via a discussion of key social barriers to open data. Additionally, I hope to motivate water resource researchers to develop a two‐way interdisciplinary engagement by making original research contributions to this larger literature. This article is categorized under: Engineering Water Science of Water > Methods Human Water > Water Governance Human Water > Water as Imagined and Represented