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Summary and Conclusions SYNOPSIS The drama of geophysics is now vividly transmitted by views of our living, changing planet from space platforms. This perspective has inspired multidisciplinary efforts to describe and understand the interactive functioning and continuing evolution of the earth's com- ponent parts. In turn, these efforts have brought a fuller appreciation of the central role that the global circulation of water plays in the interaction of the earth's solid surface with its atmosphere and ocean, particularly in regulating the physical climate systems and the bio- geochemical cycles. This realization of the importance of water to the earth system at geophysical space and time scales has profound implications for the research and educational infrastructure of hydrologic science. We cannot build the necessary scientific understanding of hydrology at a global scale from the traditional research and educational programs that have been designed to serve the pragmatic needs of the engi- . . nearing community. Investments in water resources management over the last century have helped provide the remarkable levels of public health and safety enjoyed by the urban populations of the developed world. While we have spent lavishly to cope with the scarcities and excesses of water and to ensure its potability, we have invested relatively little in the basic science underlying water's other roles in the planetary mechanisms. The committee believes that this science, hydrologic science, has a

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2 OPPORTUNITIES IN THE HYDROLOGIC SCIENCES natural place as a geoscience alongside the atmospheric, ocean, and solid earth sciences; yet in the modern scientific establishment this niche is vacant. The supporting scientific infrastructure, including distinct educational programs, research grant programs, and research institutions, does not now exist for hydrologic science and must be put in place. This report presents the supporting arguments and recommends specific remedial actions. WATER AND LIFE Life arose in water and there began its evolution from the simple plants and animals that were virtually all water to humans, who by weight are approximately two-thirds water. Water has unique physical and chemical properties that enable it to play key roles in regulating the metabolism of plants, animals, and even our living planet. Elixir of life The peculiar molecular structure of water makes it an almost universal solvent; no other liquid can dissolve such a wide variety of compounds. Because cell membranes are permeable only to certain dissolved substances, water is the elixir of life, essential as blood and lymph both for the nourishment of cells and for the removal of their wastes. It plays this same role at all higher levels of life's organization: for the individual plant or animal, the household, the city, civilization, and, apparently, for the earth itself. Climatic thermostat A gram of water can absorb more heat for each degree of temperature rise than can most other substances. This high specific heat gives water a correspondingly large thermal inertia, making it the flywheel of the global heat engine. Because of water's special character, oceans and large lakes fluctuate little in temperature, and the heat-sensitive proteins within plant and animal cells are insulated by their aqueous baths. Global heat exchanger When changing among its liquid, vapor, and solid states (at constant temperature), a gram of water absorbs or yields more heat than do most other substances. The phase changes of water on the earth are powered by the sun. Solar energy stored in water vapor as latent heat during evaporation travels with the vapor in the atmospheric circulation until it is released when the vapor condenses into precipitation. In this way both water and heat are redistributed globally. The range of surface temperatures and pressures on the earth is such that water is plentiful in its life-supporting liquid state and yet moves freely and vigorously to its vapor and solid states as well. The more we learn about our desiccated, and apparently barren,

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SUMMARY AND CONCLUSIONS 3 neighboring planets, the more we wonder if our good fortune is not a result as well as the cause of life on the earth. EARTH'S HYDROLOGIC CYCLE The pathway of water as it moves in its various phases through the atmosphere, to the earth, over and through the land, to the ocean, and back to the atmosphere is known as the hydrologic cycle. This cycle is the framework of hydrologic science and occurs over a wide range of space and time scales. In one round trip through this cycle a single water molecule may assume various roles: dissolving minerals from the soil and carrying them to nourish plants, quenching the thirst of humans, acting as a coolant, and serving as a solvent or chemical reactant in industrial processes. In any of these roles this water molecule may return to its hydrologic pathway in new chemical compounds or, along with its associates, it may be mixed with various solid and liquid substances. Thus the hydrologic cycle is not defined solely by the quantity of water moving through it but also by that water's quality. Furthermore, many Wings affected by water in its relentlessly repetitive cycle have their own effects on that cycle. Prime examples are plants, which regulate the rate at which a land surface returns water vapor to the atmosphere, and humans, who alter nearly all aspects of water on land. Such interactions are not limited to living things, however, if we consider longer time scales. For example, alluvial aquifers, formed over geological time through erosion and sedimentation by glaciers and streams, form a dynamic component of the contemporary hydrologic system. Our water-based environment has arrived at its present state through eons of convolution of climate, life, and the solid earth. The central role of water in the evolution and operation of the earth system provides a rationale for seeing hydrologic science as a geoscience of stature equal to that of the atmospheric, ocean, and solid earth sciences. We now understand that the hand of mankind is altering the earth's environment on a global scale by virtue of such widespread activities as deforestation, urbanization, and pollution. These actions of humans now extend to the "ends of the earth": high latitudes, deserts, and mountains, where they affect sensitive environments and where hy- drologic data and understanding are absent; they cause global-scale change in the hydrologic cycle. Ensuring the security of water supplies and protecting against flood, drought, and rising sea level require that we understand these changes. We must learn to incorporate

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4 OPPORTUNITIES IN THE HYDROLOGIC SCIENCES human activity as an active component of the hydrologic cycle in all environments. A DISTINCT GEOSCIENCE Over the past 60 years, the evolution of hydrologic science has been in the direction of ever-increasing space and time scales, from small catchment to large river basin to the earth system, and from storm event to seasonal cycle to climatic trend. Hydrologic science should be viewed as a geoscience interactive on a wide range of space and time scales with the ocean, atmospheric, and solid earth sciences as well as with plant and animal sciences. To establish and retain the individuality of hydrologic science as a distinct geoscience, its domain is defined as follows: Continental water processes the physical and chemical processes characterizing or driven by the cycling of continental water (solid, liquid, and vapor) at all scales (from the microprocesses of soil water to the global processes of hydroclimatology) as well as those biologi- cal processes that interact significantly with the water cycle. (This restrictive treatment of biological processes is meant to include those that are an active part of the water cycle, such as vegetal transpiration and many human activities, but to exclude those that merely respond to water, such as the life cycle of aquatic organisms.) Global water balance the spatial and temporal characteristics of the water balance (solid, liquid, and vapor) in all compartments of the global system: atmosphere, oceans, and continents. (This includes water masses, residence times, interracial fluxes, and pathways between the compartments. It does not include those physical, chemical, or biological processes internal to the atmosphere and ocean compartments.) SOME UNSOLVED PROBLEMS The enlarged scope of hydrologic science brings increased com- plexity and increased interaction with allied sciences. New questions of physical behavior arise, such as the following: How do we aggregate the dynamic behavior of hydrologic pro- cesses at various space and time scales in the presence of great natu- ral heterogeneity? What are the feedback sensitivities of atmospheric dynamics and climate to changes in land surface hydrology, and how do these vary with season and geography?

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SUMMARY AND CONCLUSIONS 5 What can the soil, sediment, vegetation, and stream network geometry tell us about river basin history and about the expected hydrologic response to future climate change? What can we learn about the equilibrium and stability of mois- ture states and vegetation patterns? Is "chaotic" behavior a possibility? How are water, sediment, and nutrients exchanged between river channels and their floodplains? What are the states and the space-time variabilities of the global water reservoirs and their associated water fluxes? How can the necessary and fundamental links between the de- terministic and stochastic models of rainfall fields be established? What are the physical factors that control the snow cover-climate feedback process and its role as an amplifier of climatic change? Fundamental chemical and biological questions arise also that are often soil-related and hence at the other extreme of scale. A few examples will give the flavor: How can we employ modern geochemical techniques to trace water pathways, to understand the natural buffering of anthropo- genic acids, and to reveal ancient hydroclimatology? What is the nature of the feedback processes that occur between biochemical processes and the various physical transport mechanisms in the soil? What is the relative importance of different flow paths and residence times to the chemistry of subsurface water? How much transfer of adsorbed materials from one grain to another occurs during streambed storage? How should we quantify the processes that determine the transport and fate of synthetic organic chemicals that enter the ground water system? These and many other fundamental problems of hydrologic sci- ence must be addressed to provide the ingredients for solving the sharpening conflicts of humans and nature. Many, if not most, will require coordinated multidisciplinary field studies conducted at the appropriate scales. Others, such as the measurement of unknown oceanic precipitation and evaporation, will require sensors, often satellite- borne, that are still undeveloped. Progress in many areas of hydro- logic science is currently limited by a lack of (high-quality) data. DATA ISSUES Hydrologic processes are highly variable in space and time, and this variability exists at all scales, from centimeters to continental

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6 OPPORTUNITIES IN THE HYDROLOGIC SCIENCES scales, from minutes to years. Data collection over such a range of scales is difficult and expensive, and so hydrologic models usually conceptualize processes based on simple, often homogeneous, models of nature. This forced oversimplification is impeding both scientific understanding and management of resources. In the history of the hydrologic sciences as in other sciences, most of the significant advances have resulted from new measurements, yet today there is a schism between data collectors and analysts. The pioneers of modern hydrology were active observers and measurers, yet now, designing and executing data collection programs (as dis- tinct from field experiments with a specific research objective) are too often viewed as mundane or routine. It is therefore difficult for agencies and individuals to be doggedly persistent about the continuity of high-quality hydrologic data sets. In the excitement about glamor- ous scientific and social issues, the scientific community tends to allow data collection programs to erode. Such programs provide the basis for understanding hydrologic systems and document changes in the regional and global environments. Modeling and data collection are not independent processes. Ideally, each drives and directs the other. Better models illuminate the type and quantity of data that are required to test hypotheses. Better data, in turn, permit the development of better and more complete models and new hypotheses. We must reemphasize the value and importance of observational and experimental skills. EDUCATIONAL ISSUES Higher education in hydrology, especially at the graduate level, has long been the province of engineering departments in most uni- versities. Doctoral and master's degree programs administered by these departments have been directed toward the traditional concerns of water resources development, hazard mitigation, and water man- agement as predicated on societal needs. The research focus in these departments has properly been the analysis and solution of problems related to engineering practice, on the premise that these problems contribute palpably to the technical knowledge base required for water resources allocation, the management of floods and droughts, and pollution control. Current societal needs, as expressed through legislative action or executive orders, are as important to the choice of research problems and their methods of solution as are the flow of scientific ideas and technological breakthroughs. This well-developed and successful line of inquiry differs markedly from that pursued in the pure sciences, such as chemistry. The difference, in fact, is exactly analogous to that between the disciplines of chemis-

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SUMMARY AND CONCLUSIONS 7 try and chemical engineering. Chemistry is the science that deals with the composition, structure, and properties of substances and the reactions that they undergo. Chemical engineering deals with the design, development, and application of manufacturing processes in which materials undergo changes in their properties. The first disci- pline is a science, dealing with puzzle solving (i.e., motivated by a question), whereas the second is an application of science, dealing with problem solving (i.e., motivated by the answer). Hydrology has a long and distinguished history of problem solving, but where is the antecedent science of puzzle solving? The education of hydrologic scientists offers challenges as great as those in engineering hydrology, but the spirit of the enterprise is different, just as it is between education in chemistry and in chemical engineering. The choice of research problem is occasioned by its level of development within the hierarchy of the science, by the availability of new methods with which to solve it, and by the desire to understand a hydrologic phenomenon more deeply. The solution of the problem advances the development of the science and expands the conceptual framework that gives it meaning. It is this kind of internally driven intellectual pursuit that motivates the pure scientist and that must be instilled by the educational process that forms her or his professional outlook. That is the challenge to hydrologic science, and it differs from the challenge to engineering. Graduate Education in the Hydrologic Sciences As a result of this challenge, graduate education in the hydrologic sciences should be pursued independently of civil engineering. Some universities do this by housing "water science" programs in depart- ments such as geography or geology. However, few offer a coherent program that treats hydrology as a separate geoscience. It is a premise of this report that hydrology expanded in scope, importance, and potential- must escape mere inclusion as an option under engineering, geology, or natural resources programs. Establishment of specialized Ph.D. and master's degree programs is, therefore, necessary to enhance the identity of hydrology as an established science. Graduates are needed who are considered first and foremost as hydrologists, not as civil engineers or geologists who know something about hydrology. Undergraduate Education in the Hydrologic Sciences Few undergraduate programs exist in hydrology, and most profes- sionals gain entry to the field from engineering or from the geo- sciences. However, the geosciences and civil engineering both have

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8 OPPORTUNITIES IN THE HYDROLOGIC SCIENCES suffered a precipitous decline in undergraduate enrollment in recent years. Thus the hydrologic sciences face a potential recruitment problem created, at least in part, by the increasing difficulties students face as they enroll in courses in these majors, the primary obstacle being the required capabilities in physical science and mathematics. The nearly universal demand for computer literacy has left stu- dents with little time for commitment to laboratory and field courses. The consequences of this are both profound and disturbing. Students (and faculty) have become separated from the physical world they seek to master. If a major rejuvenation of the "observational" components of higher education were to occur, it would serve to improve the quality of professionals entering hydrologic science and also perhaps to attract larger numbers of experientially motivated students to the field. Science Education from Kindergarten Through High School The discussion above makes clear that the success of graduate pro- grams in the hydrologic sciences will depend on the quality of un- dergraduate preparation in pure science and mathematics, which, in turn, depends critically on the educational background obtained in precollegiate years. Like the statistics for geosciences and civil engi- neering majors, those for science education among high school students show a dismal trend. Less than 50 percent of high school graduates in the United States have completed more than one year of mathematics and one year of basic science. Less than 10 percent have taken a physics course. SCIENTIFIC PRIORITIES The diversity and range of scale of the frontier problems in hydro- logic science are illustrated clearly by the examples listed earlier. The committee ranked a long list of these problems according to their expected contribution to scientific understanding under the premises that (1) the largest potential for such contribution lies at the least explored scales and in making the linkages across scales, and (2) hydrologic science is currently data-limited. From the most promis- ing on this ranked list, allied problems were grouped into a small set of broader but unranked research areas of highest priority. Priority Categories of Scientific Opportunity (Unranked) The committee suggests the following five research areas as those now offering the greatest expected contribution to the understanding of hydrologic science.

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SUMMARY AND CONCLUSIONS 9 Chemical and Biological Components of the Hydrologic Cycle In combination with components of the hydrologic cycle, aqueous geochemistry is the key to understanding many of the pathways of water through soil and rock, for revealing historical states having value in climate research, and for reconstructing the erosional history of continents. Together with the physics of flow in geologic media, aquatic chemistry and microbiology will reveal solute transforma- tions, biogeochemical functioning, and the mechanisms for both con- tamination and purification of soils and water. Water is the basis for much ecosystem structure, and many ecosys- tems are active participants in the hydrologic cycle. Understanding these interactions between ecosystems and the hydrologic cycle is essential to interpreting, forecasting, and even ameliorating global climate change. Scaling of Dynamic Behavior In varied guises throughout hydrologic science we encounter questions concerning the quantitative relationship between the same process occurring at disparate spatial or temporal scales. Most frequently perhaps, these are problems of complex aggregation that are confounding our attempts to quantify predictions of large-scale hydrologic processes. The physics of a nonlinear process is well known under idealized, one-dimensional laboratory conditions, and we wish to quantify the process under the three-dimensional heterogeneity of natural sys- tems, which are orders of magnitude larger in scale. This occurs in estimating the fluxes of moisture and heat across mesoscale land sur- faces and in predicting the fluvial transport of a mixture of sediment grains in river valleys. It arises in attempting to extend tracer tests carried out over distances of 10 to 50 m in an aquifer to prediction of solute transport over distances of hundreds of meters to kilometers. It occurs in extrapolating measurements of medium properties in a small number of deep boreholes (as in the Continental Scientific Drilling Program) to characterize fluid fluxes at crustal depth. The inverse problem, disaggregating conditions at large scale to obtain small-scale information, arises commonly in the parameterization of subgrid-scale processes in climate models and in inferring the subpixel properties of remote sensor images. Solving these problems will require well-conceived field data collection programs in concert with analysis directed toward "renormalization" of the underlying dynamics. Success will bring to hydrologic science the power of generalization, with its dividends of insight and economy of effort.

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10 OPPORTUNITIES IN THE HYDROLOGIC SCIENCES Land Surface-Atmosphere Interactions Understanding the reciprocal influences between land surface processes and weather and climate is more than an interesting basic research question; it has become especially urgent because of accelerating hu- man-induced changes in land surface characteristics in the United States and globally. The issues are important from the mesoscale upward to continental scales. Our knowledge of the time and space distributions of rainfall, soil moisture, ground water recharge, and evapotranspiration are remarkably inadequate, in part because his- torical data bases are point measurements from which we have attempted extrapolation to large-scale fields. Our knowledge of their variabil- ity, and of the sensitivity of local and regional climates to alterations in land surface properties, is especially poor. The opportunity now exists for great progress on these issues for the following reasons. Remote sensing tools are available from aircraft and satellites for measurement of many land surface properties. Critical field experiments such as the completed First ISLSCP (International Satellite Land Surface Climatology Program) Field Experiment (FIFE) and the Hydrologic-Atmospheric Pilot Experiments-Modelisation du Bilan Hydrique (HAPEX-MOBILHY), and others under way and planned, promise to improve both measurement and understanding of hydro- logic reservoirs and fluxes on several scales. Additional experiments in a range of environments are needed. Finally, numerical models exist that are capable of integrating results from regional and global measurement programs and focusing issues for future experiments. Coordinated Global-scale Observation of Water Reservoirs and the Fluxes of Water and Energy Regional- and continental-scale water resources forecasts and many issues of global change depend for their resolution on a detailed understanding of the state and variability of the global water bal- ance. Our current knowledge is spotty in its areal coverage; highly uneven in its quality; limited in character to the quantities of primary historical interest (namely precipitation, streamflow, and surface water reservoirs); and largely unavailable still as homogeneous, coordinated, global data sets. The World Climate Data Program (WCDP) has un- dertaken the considerable task of assembling the historical and current data, and the World Climate Research Program (WCRP) is planning the necessary global experimental program, the Global Energy and Water Cycle Experiment (GEWEX), to place future observations on a sound and coordinated scientific foundation. Many nations must contribute for this program to be successful. The United States should

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SUMMARY AND CONCLUSIONS 11 play a major role in GEWEX through the support of key experimental components and accompanying modeling efforts. Of particular im- portance in this regard is NASA's Earth Observing System (EOS) program, which will include observing and data systems as well as scientific experiments for multidisciplinary study of the earth as a system. Hydrologic Effects of Human Activity For at least two decades hydrologists have acknowledged that hu- mans are an active and increasingly significant component of the hydrologic cycle. Quantitative forecasts of anthropogenic hydrologic change are hampered, however, by their being largely indistinguish- able from the temporal variability of the "natural" system. Experiment and analysis need to be focused on this question. Identification of the signal of change within the background noise of spatial and temporal variability will require observations at regional scale and over many annual cycles. Forecasting the course of future change will be eased by understanding what changes have already occurred. Data Requirements Maintenance of Continuous Long-Term Data Sets The hydrologic sciences use data that are collected for operational purposes as well as those collected specifically for science. Improve- ments in the use of operational data require that special attention be given to the maintenance of continuous long-term data sets of estab- lished quality and reliability. Experience has shown that exciting scientific and social issues often lead to an erosion in the data collection programs that provide a basis for much of our understanding of hydrologic systems and that document changes in regional and global environments. Improved Information Management The increasing emphasis on global-scale hydrology and the increasing importance of satellite and ground-based remote sensing lead to use of large volumes of data that are collected by many different agen- cies. An information management system is needed that would al- low searching many data bases and integrating data collected at dif- ferent scales and by different agencies. Interpretation of Remote Sensing Data Effective use of remote sensing data is now too difficult for many hydrologic scientists, because the interpretation often depends on a

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2 OPPORTUNITIES IN THE HYDROLOGIC SCIENCES detailed knowledge of sensor characteristics and electromagnetic properties of the surface and atmosphere. Hydrologic data products should be made available in a form such that scientists who are not remote sensing experts can easily use the information derived. Dissemination of Data from Multidisciplinary Experiments Special integrated studies, such as HAPEX, FIFE, and GEWEX, that involve intensive data collection and investigation of the fluxes of water, energy, sediment, and various chemical species, produce high- quality data sets that have value lasting far beyond the duration of the experiment. Optimal use of these data requires broader and more timely distribution beyond the community of scientists who are involved in the experiments. Education Requirements Multidisciplinary Graduate Education Program c ~ The broad range of education inputs to graduate study in hydro- logic science necessitates the formation of a multidisciplinary pro- gram in the hydrologic sciences. This program should be either a department unit or a confederation of faculty from host departments that is assured of autonomy and resources by upper-level administration. The program would educate graduate students who are considered first and foremost as hydrologists, not geologists, geographers, or engineers who have some background in hydrology. Experience with Observation and Experimentation The changing nature of hydrologic science requires the develop- ment of coordinated, multidisciplinary, large-scale field experiments. Graduate students should be given experience with modern observa- tional equipment and technologies within their university programs, and mechanisms should be developed to facilitate their participation in these experiments, irrespective of their university of study. When the experiments are planned, the inclusion of a diverse array of studies should be an integral part of the plan. Undergraduate students of science should have experience with measurement of natural phenomena, preferably in field situations as well as in controlled laboratory settings. Visibility to Undergraduate Students Programs should be developed to make hydrologic science more visible as a scientific discipline to undergraduate students. These programs should include such elements as research participation, in- ternships at laboratories and institutes, curricula that introduce the

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SUMMARY AND CONCLUSIONS 13 latest innovations, visiting distinguished lecturers, media develop- ment, and in-service institutes for teachers. RESOURCES AND STRATEGIES Development of hydrology as a science is vital to the current effort to understand the interactive behavior of the earth system. Achiev- ing this comprehensive understanding will require the kind of long- term disciplinary and interdisciplinary effort that can be sustained only by a vigorous scientific infrastructure. In conclusion this committee presents those resources and strategic actions that it believes are necessary to support a viable hydrologic science in the United States. Resources Research Grant Programs The central role of water in the earth system over a broad range of space and time scales provides the scientific rationale for a unified development of hydrologic science. The associated need to create and maintain a cadre of hydrologic scientists requires development of a focused image and identity for this science. Establishment of distinct but coordinated research grant programs in the hydrologic sciences would address both of these issues. Support for research in hydrologic science in the United States is scattered among various agencies of the federal government. In keeping with the pragmatic origins of the science, the "action" agencies, such as the U.S. Geological Survey, the U.S. Environmental Protection Agency, the National Aeronautics and Space Administration, the National Weather Service, and the Agricultural Research Service, manage water-related research programs oriented to their own specific missions. The basic science fraction of this research, quite properly, is small in comparison with the applied. The amount of funds spent in-house is large with respect to external grants, and there is little coordination of effort at the interagency level. Support for basic research in hydrologic science is concentrated within the National Science Foundation but is diffused there among the divisions of the Geosciences Directorate, each with a mandate oriented toward its own interests. This partitioning not only slights important hydrologic areas, such as aqueous chemistry and the earth's vegetation cover, but also ensures that there is no cultivation of a coherent research program in hydrologic science, and that the science achieves no established identity. A broad research grant program is needed that accommodates hydrology's natural role as a coupler of

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14 OPPORTUNITIES IN THE HYDROLOGIC SCIENCES traditional disciplines, particularly solid earth science, atmospheric science, and terrestrial ecology. Fellowships, Internships, and Instructional Equipment At the graduate level, this committee recommends establishment of special research fellowships in the hydrologic sciences. These should be designed to train students for research in a specific branch of hydrology and to increase the number of students equipped to investigate interdisciplinary problems. Travel fellowships will enable students to enroll in specific courses, to interact with key scientists, and to participate in large-scale, coordinated experiments. Fellowships are especially important in increasing participation by women, ethnic minorities, and the handicapped, as are internships for the retraining of mature scientists from allied disciplines. At the undergraduate level, there is a strong need for providing modern, sensitive instructional equipment for students' use in the field and to back this up with logistical support for field trips and field classes. Summer or academic year institutes for kindergarten through twelfth grade teachers can provide a basic science and mathematics background taught in the context of hydrology. Coordinated Field Experiments Field studies involving multiple disciplines can often achieve more than the sum of their separate disciplinary goals by coordination of observations around a common, multidisciplinary objective. Such coordinated field experiments include short-term, large-scale, multicollaborator studies, sometimes called campaigns or given acronyms such as GEWEX. These campaigns (e.g., the Global Atmosphere Re- search Program/Atlantic Tropical Experiment (GATE) and the Tropical Ocean and Global Atmosphere (TOGA) Program are widely used by the other geosciences, particularly to characterize mesoscale and larger phenomena, but are just coming into use in hydrology (e.g., HAPEX and FIFE). Such a program serves as an umbrella under which indi- vidual investigators carry out their work. Support of well-conceived campaigns is essential to the advancement of hydrologic science. A second type of coordinated field experiment is the long-term or base-line study, such as the Long-Term Ecological Research (LTER) Program being carried out at specific sites under the leadership of the National Science Foundation. Formalized agency programs sup- porting faculty and student involvement in field experiments and instruction at these facilities are badly needed. It should be the responsibility of universities and government agencies

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SUMMARY AND CONCLUSIONS 15 to inculcate the necessary planning and observational skills for all these modes of research through a steadfast, long-term commitment to the teaching and financial support of field work in the hydrologic sciences. Long-Term Observations Continuous, long-term records of hydrologic-state variables (e.g., soil moisture, temperature, atmospheric humidity, and concentration of dissolved and suspended substances) and hydrologic fluxes (e.g., precipitation, streamflow, and evaporation) are essential, among other things, to quantify the variability of these quantities. These records have value in such areas as identification of global change (e.g., the Mauna Loa carbon dioxide record), isolation of mechanisms, and es- timation of the risk of flood and drought. The committee must renew the plea here for unwavering support of the collection and storage of long-term hydrologic records. These resources are like a patient's medical record: useless during apparent health, but invaluable when illness appears. The only certainty is that if records are not kept, they will not be available when needed. Access to Data Bases The immediate, unrefined products of observation and experimen- tation are scientific data. These are obviously available to those who collect them, but their primary value is often realized by others at a later date and in a quite different scientific context. For hydrologic science to move forward it is essential that data sets, once acquired, be properly identified and described (i.e., purpose, location, instru- ments, spatial and temporal coverage, and so forth), be cataloged and archived (including archival maintenance), and be made available to the scientific community at reasonable cost and effort. Resources are needed for these tasks. Strategies To further the recognition and establishment of hydrologic science as a separate geoscience, hydrologists can take many actions, either individually or through their scientific societies. These include the following: Make use of relevant scientific societies as platforms for com- munication, advocacy, organization, and education. Cultivate interest in hydrologic science among the appropriate mission-oriented agencies of the federal government. There is a need

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16 OPPORTUNITIES IN THE HYDROLOGIC SCIENCES to argue for the allocation of a greater fraction of water research money to be spent by the agencies on basic hydrologic science. There is further need to seek interagency planning and coordination of how these monies are used. Consider the establishment of a separate journal for hydrologic science. Stimulate joint meetings and symposia among the relevant sci- entific societies concerning issues of hydrologic science in order to foster interdisciplinary understanding and cooperation. Review, in five years, the progress toward achieving the goals elaborated in this report, assessing the vitality of the field, surveying the changes that have occurred, and making recommendations for further action. CONCLUSION To meet emerging challenges to our environment we must devote more attention to the hydrologic science underlying water's geophysical and biogeochemical role in supporting life on the earth. The needed understanding will be built from long-term, large-scale coordinated data sets and, in a departure from current practices, it will be founded on a multidisciplinary education emphasizing the basic sciences. The supporting educational and research infrastructure must be put in place. The benefits society will ultimately receive from a thorough scientific understanding of water behavior are many. Advances in the areas of irrigation, drinking water and ground water supplies, improved rec- reational areas and wildlife habitat, and flood and drought forecasting and planning are only a few examples. Improved hydrologic science will provide a foundation for decision making, resulting in protection and improved management of the world's water resources.