AGU and AMS Town Hall Meeting Presentation
WATER CYCLE STUDY GROUP
Appointed by U.S. Global Change Research Program (formally, Robert Corell, Chair, Subcommittee on Global Change Research (SGCR) of the Committee on Environment and Natural Resources (CENR) which in turn is one of nine committees under the National Science and Technology Council (NSTC)).
- Charge, as summarized in letter of appointment to WCSG members, is to "formulate a research strategy and scientific plan for investigating the global water cycle, its role in climate, and the fundamental processes that govern the availability and the biogeochemistry of water resources, [and to] develop the strategy and science plan for a national program."
- Chair is George Hornberger (Department of Environmental Sciences, University of Virginia)
- Parallels with U.S. Carbon Cycle Science Plan (Sarmiento and Wofsy, 1999) have been noted
Science Plan is to produce:
- A quantitative understanding of atmospheric, terrestrial, and oceanic interactions that govern water and energy cycles on intraseasonal to centennial time scales and on global and regional scales. This includes, inter alia, the roles of water vapor, clouds, and precipitation processes, biogeochemical processes, terrestrial and aquatic ecosystem influences, and the role of surface and subsurface waters within the overall hydrologic cycle;
- An improved representation of these processes in climate and other models, across the relevant space and time scales, that will allow simulation of the hydrological cycle and its interactions with the rest of the earth system;
- An understanding of the response of the water cycle to environmental change and the accompanying impact on water resources;
- A capability to model, and, where appropriate, predict variations in global and regional hydrologic processes and water resources on seasonal to interannual time scales and longer time scales;
- The requirements for comprehensive, systematic space-based, ground-based, and in situ observations in support of the water cycle science objectives, with consideration of the compatibility of measurements across scales and processes; and
- Guidance on the linkages, areas of cooperation and potential integration with other relevant national and international programs to make this initiative a success.
SCHEDULE:
- Preliminary outline by September, 1999 (available at
www.ce.washington.edu/~aww/dpl_eos/eos_article.htm)
- Interim draft report by late January, 2000
- Final Document by July, 2000
RATIONALE
A global cycle with regional and local impacts
"Water, and its cycling in the Earth system, is critical for both human populations and ecosystems
To date, our ability to assess variability in water resource availability and to predict and mitigate impacts of hydrologic extremes has been hampered by large uncertainties that result from our limited understanding of the global scale water cycle.
An integrated program of research devoted to improving scientific understanding of the water cycle at a broad spectrum of scales, including global, regional and local is necessary."
- Recent human activities and climate variability are together perturbing the global water cycle in ways that current societies have never experienced.
"Variability in hydrological processes occurs over a range of time and space scales. [examples
] Changes in land cover and land use have been enormous
The world population has more than doubled since 1950
These changes have local, regional, and even global effects on the hydrological cycle
"
- Current societies are ill equipped to respond to resulting stresses on water resources, agriculture, and natural ecosystems.
"The development and exploitation of new scientific methods and results have the potential to improve the efficiency of our management approaches, particularly if the scientific advancements are tuned to meet the needs of water, land-use, and natural resource management
"
- New approaches to measurement and modeling of components of the Earths water cycle are currently under development.
"Remotely sensed observations of land surface conditions from satellites and suborbital platforms (e.g., aircraft and balloons) provide synoptic high-resolution coverage that is unprecedented in the hydrological sciences
New developments in ground based instruments
could result in continuous records of hydrological parameters at a variety of locations
The continued development of data assimilation methods for use in hydrology will make hydrological data available where they have not been heretofore."
- Benefits and critical elements of an integrated water cycle science program
"The emerging monitoring and modeling efforts, as well as new developments in these areas, should allow for rapid improvements in capabilities to predict water cycle variability and extremes over a variety of time and space scales
Understanding the global water cycle is also central to understanding the potential human, economic and ecological consequences of global environmental change."
THEREFORE
"What is needed in a water cycle science program, however, goes beyond simply accelerating research that is currently underway. We need new ways of developing scientific understanding of water and its movement in the earth system, that are not constrained by the traditional disciplines atmospheric, ocean, and hydrological sciences - which structured our study of water problems to date. The future opportunities and challenges exist across the disciplines, and it is at the boundaries of the traditional disciplines where the new frontiers lie."
SCIENCE QUESTIONS AND GOALS
Science Question 1
: What are the underlying causes of variation in the water cycle on both global and regional scales, and to what extent is this variation induced by human activity.
Goal 1: Quantify variability in the water cycle
- Improve our ability to estimate hydrologic state variables and fluxes at and below the land surface, in the upper and lower atmosphere, and at the air-sea interface. This will involve, for example, taking full advantage of new measurement technologies and new approaches for interpreting the data record.
- Develop improved comprehensive strategies for estimating the global water cycle. Include in such strategies, for example, better process understanding and the enhanced use of data assimilation techniques, and consider space-time trade-offs in measurement approaches and the parallel treatment of the global energy cycle. Use the resulting information to reduce significantly the uncertainty in the closure of atmospheric and terrestrial water balances.
- Develop, over continental and global domains, and across a diversity of data sources, types, and scales, approaches for identifying and interpreting signatures of large-scale change (such as an acceleration) in the water cycle.
Goal 2: Distinguish human-induced and natural variations in the water cycle.
Through process studies, field campaigns, and other observational analysis, improve the capability of models to reproduce observed variability in the water cycle over a range of space and time scales.
- Through the use of these models and additional observational studies, determine the signature of human activities on the water cycle. Examine the observational record for evidence of this signature, and establish new observational and modeling strategies needed to monitor human impacts into the future.
Science Question 2
: To what extent are variations in the global and regional water cycle predictable?
Goal 1. Demonstrate the degree of predictability of variations in the water cycle over a range of space and time scales.
- Develop an understanding of the multiple time scale response of the water cycle to changes in sea surface temperature, land surface conditions (soil moisture, snow, and vegetation), land use, and other anthropogenic climate agents. Quantify the relative roles of these various processes in determining water cycle predictability.
- Quantify the inherent predictability of fluctuations in the water cycle at daily, seasonal, annual, interannual, and decadal time scales from global scales to stream basins. Identify the limits in our ability to make predictions associated with the limitations of observations and models.
- Develop, assess and refine the capability of global and regional coupled land-atmosphere and surface hydrologic models to predict global and regional-scale hydrometeorological extremes, including droughts, heat waves and floods and attendant extreme departures in the levels of rivers, lakes, water reservoirs, and ground water.
Goal 2. Establish a scientific basis for making predictions and estimates of uncertainty useful for water-resources management, natural hazard mitigation, decision-making and policy guidance.
- Identify those regions where water resources decision-making is vulnerable to climate fluctuations at different time scales, and where natural hazards are likely to have a large impact on human systems and ecosystems. Identify those time scales at which water resources decisions and natural hazard mitigation strategies can be effected.
- Develop a scientific methodology for analyzing, assessing and understanding the effects of multiple stresses on human systems and ecosystems.
- Develop a scientifically-based methodology for (1) estimating uncertainty in predictions of water cycle changes, (2) determining the information gaps, needs, valuation and barriers to effective use of scientific information, and (3) coupling hydrological, ecological and economic risks.
Science Question 3: How will variability and changes in the cycling of water through terrestrial and freshwater ecosystems be linked to variability and changes in cycling of carbon, nitrogen and other nutrients at regional and global scales?
Goal 1. Develop observations and experiments that characterize the coupling and feedbacks of water, carbon, and nitrogen cycles.
- Integrate existing diverse data sets to evaluate coupling of these cycles with emphasis on retrospective analysis of periods of hydrologic extremes, and determine the key data gaps in current observation systems.
- Develop more powerful in situ monitoring and remote sensing technology and design monitoring networks and experiments that will provide more complete information in the appropriate space and time scales for evaluating the coupling of these cycles. Develop relational databases capable of integrating information that leads to understanding multiple stresses from climate and land use.
Goal 2. Develop a quantitative, predictive framework through synthesis of concepts from different disciplines that utilizes these data sets.
- Bring together hydrologic watershed concepts, terrestrial ecosystem concepts, and river continuum concepts to develop models for large-scale watershed ecosystem networks. Address multiple stresses and diverse climate drivers to quantify the roles of land use change and changes in the hydrologic cycle.
- Concurrently, use the new conceptual framework and models to organize and interpret data from the monitoring networks and larger scale experiments. Integrate these process models into regional- and global-scale climate models to elucidate "feedbacks" resulting from coupling of water, carbon, and nitrogen cycles. Apply these process models within decision support models and information resources for multi-objective water-resource management in an on-going manner.
Hydro Administrator
Last modified: Wed Jan 26 14:56:46 PST 2000