The Role of Science in Solving the Earth's Emerging Water Problems (2005)

THE ROLE OF SCIENCE IN SOLVING THE EARTH’S EMERGING WATER PROBLEMS

October 8-10, 2004

J. Famiglietti, Dept. of Earth System Science, University of California, Irvine; D. Alsdorf, Department of Geography, University of California, Los Angeles; D. Lettenmaier, Dept. of Civil & Environmental Engineering, University of Washington

River discharge as well as lake and wetland storage of water are critical elements of land surface hydrology and are critically important to human populations, yet they are poorly observed globally and the prospects for improvement from in-situ networks are bleak. Furthermore, off-river-channel environments, such as wetlands, floodplains are increasingly recognized for their important roles in delaying continental runoff, in biogeochemical cycling of waterborne constituents, and in trace gas exchange with the atmosphere, but the dynamics of water stored in these environments are not generally observed because flow is diffusive (non-channelized). Satellite measurements may enable hydrologists to move beyond the point-based observations provided by gauge networks to basin-wide measurements of discharge and storage, and to better understand the storage of water globally, and its dynamics. Here, some of the existing satellite-based measurements of discharge and changes in storage (e.g., SAR imagery, Altimetry, SRTM, Interferometric SAR and GRACE) are outlined along with their drawbacks. Some new methods, such as radar altimetry and Interferometric Altimetry, to remotely monitor the streamflow and changes in terrestrial surface water storage are proposed. These new techniques will provide measurements that will enable a better understanding of the land surface branch of the global hydrologic cycle, will aid in the prediction of the consequences of global change, and will be useful in water resources management. Also, the roles of wetlands, lakes, and rivers in biogeochemical cycling will be better understood using these new measurements. Finally, improved global measurements of surface water will help in obtaining better parameterizations for climate and hydrologic models.

Hidalgo H.G., Cayan D.R. and Dettinger M.D.

Scripps Institute of Oceanography

Low-frequency hydrologic variations of the western US for the past 500 years contained in gridded tree-ring reconstructions of Palmer Drought Severity Index (PDSI), were compared to PDSI projections under climate change scenarios calculated from the output of general circulation models (GCMs). Tree-ring results suggest that bidecadal and pentadecadal PDSI oscillations have been a common feature of the climate of the western US at least for the past 500 years. These variations are though to be related to similar low-frequency climate variations from the Pacific and Atlantic Ocean basins. Future PDSI projections computed from the GCM estimates of precipitation and temperature, also contain significant multidecadal variations, as well as significant negative trends. Although precipitation exhibits very little trend in many of the GCM projections for the western US, warming temperatures will drive PDSI into the dry category more frequently in the future according to the GCM data. Regional structure and change of precipitation is inconsistent across models. However, warmer climate alone will produce more frequent scarcity of water availability.

Dennis Lettenmaier¹, Charles J. Vorosmarty², Robert Naiman³

¹University of Washington, Land Surface Hydrology Research Group, ²University of New Hampshire, Water Systems Analysis Group, ³University of Washington, Aquatic and Fisheries Sciences

The water cycle figures prominently in the study of global change. In addition to greenhouse warming and concerns about an accelerated hydrologic cycle, several other anthropogenic factors interact with the water system to produce potentially global-scale effects. Prominent among these are widespread land cover change, urbanization, reservoir construction, irrigated agriculture, destruction of aquatic habitat, and pollution. A rich history of research at the local scale demonstrates the clear impact of such factors on the environment. Evidence now shows that humans are rapidly embedding themselves in the basic character of the water cycle over much broader domains. The collective significance of such a transformation of a basic element of the Earth system remains fundamentally unknown. This presentation summarizes a new project launched as part of the Earth System Science Partnership (ESSP) of the Global Environmental Change Programs (Diversitas, IGBP, IHDP, WCRP) that will study these water cycle changes. The aim of the GWSP is to catalyze our understanding of the dynamics of water in the Earth system, the unique role that humans play in the hydrologic cycle and reciprocal interactions between the biogeophysical and human components of the coupled system. A major emphasis of GWSP is on interactions, feedbacks, and thresholds, necessitating a balanced consideration of all factors at play: physical, chemical, biological, and societal. The GWSP is the product of contributions made by a broad cross-section of the water science and assessment community, with more than 150 contributors to a series of planning meetings, science scoping documents, and a recent Open Science Conference (October 2003; Portsmouth, NH). This poster reviews the scientific rationale for the initiative, presents the Project’s motivating science questions, and describes the emerging agenda for study.

C.C. McGrath and W.M. Lewis, Jr.

University of Colorado

The greenback cutthroat trout (Oncorhynchus clarki stomias) is listed as a threatened subspecies under the U.S. Endangered Species Act. Restoration efforts during the past 30 years have focused on stocking suitable habitat with hatchery-reared greenback cutthroat trout. However, non-native brook trout (Salvelinus fontinalis) continue to displace native cutthroat trout in many areas. In the past, researchers have suggested that displacement of cutthroat trout by brook trout is a result of resource competition, but competition has not been investigated directly in field studies. We documented population dynamics and feeding ecology of greenback cutthroat trout and brook trout at 10 stream sites in the Rocky Mountains. Analysis of population, body condition, stomach content, and stable isotope data were used to determine if competition for food or predation were occurring. Results indicate that brook trout decrease the survival of young greenback cutthroat trout, and that interspecific competition for food among adult trout is not the mechanism for displacement of greenback cutthroat trout. Brook trout predation on cutthroat trout was observed at low rates and does not appear to account for population declines of cutthroat trout. Describing the mechanisms of species invasion contributes to more effective management of native species; however, the greenback cutthroat trout – brook trout system suggests that mechanisms of invasion can be subtle and difficult to identify.

James E. McMahon

Lawrence Berkeley National Laboratory

(A presentation by USDOE multi-program laboratories)

Two critical infrastructures – water and energy - are inextricably linked. Significant quantities of freshwater are withdrawn by thermal power plants producing electricity; conversely, energy is required for drawing, transporting, treating and using water and for processing wastewater. Problems are already emerging in water and energy supplies in diverse locations and future trends in population and possibly climate are expected to exacerbate these problems. Scientific and technological approaches that will help characterize and address these problems include:

• Assessment, prediction and decision support

• Basic science (e.g., data and methods for evaluation of multi-scale interdependence of water cycle variability, water quality and energy production and use)

• Technological innovation

• Implementation and technology transfer

Laosheng Wu and Christine French

University of California, Riverside

At the start of the Southwest States and Pacific Islands Regional Water Quality Program in 2002, a need to assess state and regional priorities was identified. A public survey was chosen as a tool to help reach that end. A 37-question survey was adapted by the Program Team from a similar survey used in the Pacific Northwest. One version of the survey was mailed to randomly selected residents in Arizona, California, Hawaii, and Nevada. Another version was slightly modified and conducted orally in the Pacific Islands. In California, 988 surveys were returned from 2000 sent for a response rate of 49%. Based on information gathered from the survey, key areas in need of outreach efforts were identified. Clean drinking water is the most important water issue in California and the region according to the survey. Several questions asked respondents to rate the importance of clean drinking water either on its own, or in relation to other issues, and it consistently rose to the top as the most important issue. Other high priority issues identified for California are watershed management and water conservation. This knowledge, combined with information on how residents view themselves and the environment, will help public educators in California and the region craft appropriate and effective learning opportunities for specific demographic groups and the public in general.

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