Databases are critical to the successful use of computer-based models that help to identify, compare, and evaluate various impacts of alternative management policies for specific watersheds . Menu-driven, graphics-based computer programs that permit the interactive use of these impact prediction models and their databases support the iterative (sequentially repetitive), explorative, participatory and adaptive decision-making processes that typify water resources management.
Water resources data, which are stored, accessed, manipulated, and managed electronically within databases, are numbers, text, and images that characterize the quantity, quality, and spatial and temporal distributions of the supply of, and demand for, water. Data also identify and describe the physical, social, legal, economic, and institutional factors that affect how water resources are managed.
Water resources management requires a knowledge of the resources being managed. Such water resources assessments are based on measurements of physical and hydrologic conditions over time and space. The needed degree of spatial and temporal detail (that is, the resolution) and the level of accuracy of these measurements will depend on the particular management
International organizations, governmental agencies, and private companies collect and store data to support local watershed and regional river basin management activities, as well as ongoing research on more global issues related to possible climate change impacts,. These data are needed to perform the assessments used in planning and decision-making devoted to various goals:
Because of the variability of water supplies over time, these assessments are based on systematic measurement programs carried out in the past. This is why it is important today to maintain and improve networks of monitoring stations and data collection organizations.
Determining trends in water availability and quality, due to human activities and trends in climate, requires consistent data resulting from standard measurements made regularly over the long term. Long-term systematic measurement programs are normally undertaken by government agencies as part of the information infrastructure needed for national or regional development.
In many countries, there exists a single agency responsible for water measurements for all purposes. International agencies, such as the World Meteorological Organization, work toward the standardization of instruments, methods of observation and terminology, design of instrument networks, water quantity and quality monitoring, technology transfer, and local training. As in any other systematic monitoring program, it is not enough just to make the observations. The data must be quality controlled, stored, analyzed, and made available for use by many different clients. Today the Internet provides a primary access to many such databases.
The improvement of water resource measurements and assessments is needed not only for national purposes and management, but also to understand global and large-scale regional processes. For example, the water budget of the oceans, fed largely by rivers and precipitation, is critical in assessing the reasons for the observed rise in mean sea level over the past century and the likely rate of rise in a projected warming climate. Determining the sources of pollution of the seas and oceans requires information on the quality of river discharges. Yet many of the largest rivers, which carry over half of the continental water and sediments to the oceans, are inadequately measured. Evaporation and precipitation processes transfer both water and energy through components of the global climate system and must be better understood on a large scale in order to model and predict trends in the climate.
A considerable amount of data used in water resources assessments required for planning and management are now available from public agencies through the Internet. Today, one can obtain a variety of mapping and remotely sensed data, including scanned and rescaled aerial photos (Digital
In the United States, water resources data can be obtained from the websites of federal agencies such as the U.S. Geological Survey ( usgs.gov ), the Environmental Protection Agency ( epa.gov ), the U.S. Fish and Wildlife Service ( fws.gov ), the U.S. Army Corps of Engineers ( usace.army.mil ), the U.S. Bureau of Reclamation ( usbr.gov ), the U.S. Department of Agriculture ( usda.gov ), the National Aeronautics and Space Administration ( nasa.gov ), the National Oceanic and Atmospheric Administration ( noaa.gov ), and the Central Intelligence Agency ( cia.gov ).
Data are not very useful if they cannot be used effectively. Decision-support systems (DSS) are interactive graphics-based, menu-driven computer programs that link databases to models. They are designed to facilitate the input and editing of data, the execution of models desired or required (for example, to identify the economic, environmental, ecological, and social impacts of different alternatives), and the display of the results in meaningful, understandable formats.
Developments in information and computer technology, electronic communication, remote sensing, geographic information systems, instrumentation, control, and modeling are having a significant impact on research, operation, planning, environmental impact assessment, and decision-making. Visual and multimedia tools are becoming more and more useful in transferring technical knowledge to decisionmakers and policymakers as well as to the public. DSS plays an important role in water resources management.
Daniel P. Loucks
Guariso, Giorgio, and Werthner, H. Environmental Decision Support Systems. Chichester, U.K.: Ellis Horwood Limited, 1989.
Loucks, Daniel P., and J. R. da Costa, eds. Decision Support Systems: Water Resources Planning. NATO ASI Series G, Vol. 26. Berlin, Germany: Springer-Verlag, 1991.
Sprague Jr., Ralph H., and Eric D. Carlson. Building Effective Decision Support Systems. Englewood Cliffs, NJ: Prentice Hall, 1982.
A few examples of federal databases illustrate the types of applications afforded by computer and geospatial technologies. The USDA's National Resources Inventory is a sample of land-use and natural resource conditions and trends on U.S. nonfederal lands. It is the most comprehensive database of its kind ever attempted anywhere in the world.
The U.S. EPA's Watershed Atlas is a catalog of geospatial displays and analyses of information and data important for watershed protection and restoration.
EPA's home webpage provides databases and software that apply to specific environmental media (for example, water, air, land); geographic information systems in support of mapping of environmental data; and models for predicting environmental impacts and increasing the level of understanding about natural systems and the way in which they react to varying conditions.
The EPA's Environmental Information Management System accesses descriptive information (metadata) for datasets, databases, documents, models, projects, and spatial data.