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Introduction
The watershed, a physiographic area bounded by the drainage divide and within which precipitation drains to a point of interest, provides a fundamental spatial unit for hydrologic field observation and analysis. The U.S. Geological Survey (USGS) and other federal agencies undertake a wide range of activities related to the integrated analysis of phenomena occurring within watersheds. For several years the USGS has emphasized research on relatively small (generally less than 100 hectares), undisturbed watersheds to explore basic relationships in geochemical and biogeochemical cycles (Lins, 1994). This work has been quite effective in generating understanding of physical, chemical, and biological processes that affect the quantity and quality of waters in and issuing from small watersheds. In many instances fundamental research in small watersheds is justified simply because clear scientific understanding of certain processes is lacking. Contributions to fundamental knowledge are one important justification for maintaining a program of research on small, relatively undeveloped watersheds (Box 1.1).
The USGS also has recognized that there are many problems facing the nation that involve watersheds of large areal extent and watersheds in which land-use changes have substantially altered water flows and the transport of chemicals and sediments relative to pristine conditions. Efforts also are increasing to restore the hydrologic functioning of altered watersheds, and little is known about the effectiveness of restoration schemes. There is a serious need for a coordinated, long-term research effort to develop the knowledge base needed to deal with water resources issues on large and impacted watersheds. An effective program will require coordination of broad data collection activities, intensive research at small scales, and construction and verification of models of larger-scale watersheds. The USGS, as the lead federal geosciences agency responsible for assessing water resources, should support a set of activities in watershed science that focuses
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BOX 1.1 Hubbard Brook: A Laboratory for Interdisciplinary Ecosystem-Level Research The Hubbard Brook Experimental Forest (HBEF) was established in 1955 by the U.S. Forest Service as a center for hydrologic research in New England. In 1963 the research focus at the site was expanded, through a cooperative agreement between researchers at the U. S. Forest Service and Dartmouth College, to use the small watershed approach to study element cycling. During the intervening years the scope of research at the HBEF has continued to evolve through the interests of scientists, as well as in response to regional and national environmental issues. Today Hubbard Brook is a site for comprehensive ecosystem-level research (the Hubbard Brook Ecosystem Study, HBES) and involves cooperation among the U.S. Forest Service, the Institute of Ecosystems Studies of the New York Botanical Garden, numerous universities (Cornell, Dartmouth, Syracuse, Yale, New Hampshire, Pennsylvania, Wyoming, SUNY College of Environmental Science and Forestry), the Ecosystem Center of the Marine Biological Laboratory in Woods Hole, the U.S. Soil Conservation Service, and the U.S. Geological Survey. The National Science Foundation has been a major source of financial support for HBES for the past 34 years. The work has resulted in about 1,000 publications. The HBEF is a 3176-ha, bowl-shaped area within the boundaries of the White Mountain National Forest, New Hampshire. It has hilly terrain, ranging from 222 to 1015 m in altitude and except for some experimental areas is covered by unbroken forest of northern hard-woods with spruce and fir at higher elevations. Other salient features include relatively impermeable bedrock; well-defined watershed boundaries; reasonably homogeneous geological features, soil types, vegetation, and climate; year-round precipitation and streamflow; absence of major forest disturbance for about 85 years; and several clusters of similar-sized catchments where entire watersheds can be treated experimentally and compared. The presence of Mirror Lake in the Hubbard Brook Valley has provided a unique opportunity to investigate and quantify land-water interactions. Whole ecosystem manipulations include a variety of forest clearcut studies on experimental watersheds, stream chemical manipulation studies, and lake tracer experiments. |
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With careful measurements of precipitation input and stream outflow, accurate water and element balances can be constructed. A continous database has existed since 1956 for streamflow, precipitation, and other meteorological observations for eight experimental watersheds. Measurements of precipitation and streamwater chemistry have been ongoing since 1963. The long-term record at Hubbard Brook provides (1) insight into ecosystem function; (2) empirical data for testing models and generating hypotheses; (3) a record of extreme or unusual events; and (4) information that is relevant to regional, national, and global issues. Hubbard Brook is truly a site of interdisciplinary ecosystem-level research where there is close cooperation among biological, chemical, and physical scientists. |
In its Strategic Plan the USGS states a series of general goals for the agency for the next decade (USGS, 1996a). The plan recognizes that studies of water resources will remain a key activity of the agency and that reliance on the combination of three efforts—data collection, interpretative studies, and research—will continue. The plan points out that "as population increases and relocates, the overall level of water monitoring will increase in areas of high urban and agricultural water use, but it may decrease in other areas" (USGS, 1996a). These shifts may affect all three of the USGS efforts in watershed science, interpretative studies, and research, as well as data collection.
Another facet of change that has potential impact on watershed activities of the USGS is the very recent creation of the Biological Resources Division (BRD). The BRD brings new capabilities to the USGS for assessing aquatic biological resources (USGS, 1996b). Organization of efforts for building the knowledge base to solve interdisciplinary problems may be enhanced substantially through collaborations between the Water Resources Division and the BRD.
Given the importance of watershed science for addressing a host of current water-resources issues, this assessment focused on the goals and design for the watershed research effort within the USGS and sought to address the following questions:
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What should be the underlying strategy for USGS watershed research activities? What are the key design elements for an effective program in watershed science?
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What are the major opportunities for advances in the USGS's capability in watershed science?
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How should activities in water research support ongoing USGS programs, especially NAWQA (National Water Quality Assessment program) and the long-term observing networks, and vice versa?
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What should be the appropriate links with programs in watershed research and management in other agencies and institutions?
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What are the appropriate internal USGS links, given the broad array of watershed-related research going on within the agency?
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What are the implementation requirements for effective operation of watershed research activities to address important management issues?
The remainder of this report contains the analyses, conclusions, and recommendations of the committee. We provide the context for watershed activities in the USGS, that is, the need to address issues related to watershed management. The historical background for work on research watersheds is summarized, and current efforts by a number of federal agencies are discussed. With this background, the report presents a view of important focus areas for watershed research and views on key program areas to which the USGS might orient major activities to provide the necessary knowledge base for addressing critical watershed issues. The final chapter contains conclusions and recommendations that stem from the discussions, deliberations, and analyses of the committee.
