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OPPORTUNITIES IN THE HYDROLOGIC SCIENCES /~\ /~,4 ATMOSPHERIC SCIENCE - \ \ EARTH SCIENCE ~ \\ \ \\ Committee on Opportunities in the Hydrologic Sciences Water Science and Technology Board Commission on Geosciences, Environment, and Resources National Research Council NATIONAL ACADEMY PRESS Washington, D.C. 1991
NATIONAL ACADEMY PRESS 2101 Constitution Avenue, NW Washington, DC 20418 NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the committee responsible for the report were chosen for their special competences and with regard for appro- priate balance. This report has been reviewed by a group other than the authors, according to procedures approved by a Report Review Committee consisting of members of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The National Academy of Sciences is a private, nonprofit self-perpetuating society of distinguished scholars engaged in scientific and engineering research, dedicated to the furtherance of science and tech- nology and to their use for the general welfare. Upon the authority of the charter granted to it by the Congress in 1863, the Academy has a mandate that requires it to advise the federal government on scien- tific and technical matters. Dr. Frank Press is president of the National Academy of Sciences. The National Academy of Engineering was established in 1964, under the charter of the National Academy of Sciences, as a parallel organization of outstanding engineers. It is autonomous in its adminis- tration and in the selection of its members, sharing with the National Academy of Sciences the responsibility for advising the federal government. The National Academy of Engineering also sponsors engineering programs aimed at meeting national needs, encourages education and research, and recognizes the superior achievements of engineers. Dr. Robert M. White is president of the National Academy of Engineering. The Institute of Medicine was established in 1970 by the National Academy of Sciences to secure the services of eminent members of appropriate professions in the examination of policy matters pertaining to the health of the public. The Institute acts under the responsibility given to the National Academy of Sciences by its congressional charter to be an adviser to the federal government and, upon its own initiative, to identify issues of medical care, research, and education. Dr. Samuel O. Thier is president of the Institute of Medicine. The National Research Council was organized by the National Academy of Sciences in 1916 to associ- ate the broad community of science and technology with the Academy's purpose of furthering knowledge and advising the federal government. Functioning in accordance with general policies determined by the Academy, the Council has become the principal operating agency of both the National Academy of Sci- ences and the National Academy of Engineering in providing services to the government, the public, and the scientific and engineering communities. The Council is administered jointly by both Academies and the Institute of Medicine. Dr. Frank Press and Dr. Robert M. White are chairman and vice chairman, respectively, of the National Research Council. Support for this project was provided by the National Research Council, the U.S. Geological Survey and the National Weather Service under Contract No. 14-08-0001-G1506, the National Science Foundation under Grant No. EAR-8719003, the National Aeronautics and Space Administration and the Army Research Office under Contract No. NAGW-1310, the U.S. Forest Service under Agreement No. 90-G-011/R, and The Mobil Corporation. Library of Congress Cataloging-in-Publication Data Opportunities in the hydrologic sciences / Committee on Opportunities in the Hydrologic Sciences, Water Science and Technology Board, Commission on Geosciences, Environment, and Resources, National Research Council. p. cm. Includes bibliographical references and index. ISBN 0-309-04244-5 1. HydrologyVocational guidance. I. National Research Council (U.S.). Committee on Opportunities in the Hydrologic Sciences. GB665.0315 1991 551.46'0023dc20 90-49577 CIP Cover art reproduced with permission from Sally J. Bensusen. Copyright ~ 1990 by Sally J. Bensusen. Copyright @ 1991 by the National Academy of Sciences No part of this book may be reproduced by any mechanical, photographic, or electronic process, or in the form of a phonographic recording, nor may it be stored in a retrieval system, transmitted, or otherwise copied for public or private use, without written permission from the publisher, except for the purposes of official use by the U.S. govemment. Printed in the United States of America
Committee on Opportunities in the Hydrologic Sciences PETER S. EAGLESON, Massachusetts Institute of Technology, Chairman WILFRIED H. BRUTSAERT, Cornell University SAMUEL C. COLBECK, U.S. Army Cold Regions Research and Engineering Laboratory, Hanover, New Hampshire KENNETH W. CUMMINS, University of Pittsburgh JEFF DOZIER, University of California-Santa Barbara THOMAS DUNNE, University of Washington JOHN M. EDMOND, Massachusetts Institute of Technology VIJAY K. GUPTA, University of Colorado-Boulder GORDON C. JACOBY, Lamont-Doherty Geological Observatory, Palisades, New York SYUKURO MANABE, National Oceanic and Atmospheric Administration, Princeton, New Jersey SHARON E. NICHOLSON, Florida State University DONALD R. NIELSEN, University of California-Davis IGNACIO RODRIGUEZ-ITURBE, University of Iowa JACOB RUBIN, U.S. Geological Survey, Menlo Park, California J. LESLIE SMITH, University of British Columbia GARRISON SPOSITO, University of California-Berkeley WAYNE T. SWANK, U.S. Department of Agriculture, Coweeta Hydrologic Laboratory, Otto, North Carolina EDWARD J. ZIPSER, Texas A & M University Ex-Officio STEPHEN BURGES, University of Washington (WSTB member through June 1989) National Research Council Staff STEPHEN D. PARKER, Project Manager WENDY L. MELGIN, Staff Officer (through October 1989) RENEE A. HAWKINS, Project Secretary SUSAN MAURIZI, Editor Liaison Representatives GHASSEM ASRAR, National Aeronautics and Space Administration, Washington, D.C. JOHN A. MACCINI, National Science Foundation, Washington, D.C. STEVEN MOCK, U.S. Army Research Office, Research Triangle Park, North Carolina MARSHALL MOSS, U.S. Geological Survey, Tucson, Arizona JOHN SCHAAKE, National Weather Service, Silver Spring, Maryland . . .
Water Science and Technology Board MICHAEL KAVANAUGH, lames M. Montgomery Consulting Engineers, Oakland,California, Chairman NORMAN H. BROOKS, California Institute of Technology RICHARD CONWAY, Union Carbide Corporation, South Charleston, West Virginia DUANE L. GEORGESON, Metropolitan Water District, Los Angeles JAMES HEANEY, University of Florida (through June 1990) HOWARD KUNREUTHER, University of Pennsylvania G. RICHARD MARZOLF, Murray State University (through June 1990) ROBERT R. MEGLEN, University of Colorado-Denver JUDY L. MEYER, University of Georgia DONALD J. O'CONNOR, HydroQual, Inc., Glen Rock, New Jersey BETTY H. OLSON, University of California-Irvine KENNETH W. POTTER, University of Wisconsin-Madison P. SURESH CHANDRA RAO, University of Florida PATRICIA ROSENFIELD, The Carnegie Corporation of New York (through June 1990) DONALD D. RUNNELLS, University of Colorado-Boulder PHILIP C. SINGER, University of North Carolina-Chapel Hill A. DAN TARLOCK, Illinois Institute of Technology, Chicago Kent College of Law School HUGO F. THOMAS, Connecticut Department of Environmental Protection JAMES R. WALLIS, IBM Watson Research Center, Yorktown Heights, New York M. GORDON WOLMAN, The Johns Hopkins University Staff STEPHEN D. PARKER, Director SARAH CONNICK, Staff Officer SHEILA D. DAVID, Senior Staff Officer CHRIS ELFRING, Senior Staff Officer M. JEANNE AQUILINO, Administrative Specialist PATRICIA CICERO, Secretary ANITA A. HALL, Administrative Secretary MARCIA HALL, Secretary RENEE A. HAWKINS, Administrative Secretary IV
Commission on Geosciences, Environment, and Resources M. GORDON WOLMAN, The Johns Hopkins University, Chairman ROBERT C. BEARDSLEY, Woods Hole Oceanographic Institution B. CLARK BURCHFIEL, Massachusetts Institute of Technology RALPH J. CICERONE, University of California-Irvine PETER S. EAGLESON, Massachusetts Institute of Technology HELEN INGRAM, University of Arizona GENE E. LIKENS, New York Botanical Gardens SYUKURO MANABE, National Oceanic and Atmospheric Administration, Princeton, New Jersey JACK E. OLIVER, Cornell University PHILIP A. PALMER, E. I. du Pont de Nemours & Company FRANK L. PARKER, Vanderbilt University DUNCAN T. FATTEN, Arizona State University MAXINE L. SAVITZ, Allied Signal Aerospace LARRY L. SMARR, National Center for Supercomputing Applications STEVEN M. STANLEY, Case Western Reserve University CRISPIN TICKELL, Green College at the Oxford Observatory KARL K. TUREKIAN, Yale University IRVIN L. WHITE, New York State Energy Research and Development Authority JAMES H. ZUMBERGE, University of Southern California Staff STEPHEN RATTIEN, Executive Director STEPHEN D. PARKER, Associate Executive Director JANICE E. GREENE, Assistant Executive Director JEANETTE SPOON, Financial Officer CARLITA M. PERRY, Administrative Assistant v
Foreword In 1982, soon after the beginning of my term as president of the National Academy of Sciences (NAS) and chairman of the National Research Council (NRC), a major reorganization of the NRC's struc- ture was implemented. As part of this reorganization, we created the Water Science and Technology Board (WSTB) to recognize the impor- tance of water resources to the nation. The driving forces behind the WSTB's establishment were three- fold: a unit of the NRC specifically assigned to water resources would emphasize their national importance; the complexity of water science and technology issues lends itself well to the NRC's ability to approach problems in an interdisciplinary manner; and, perhaps most important, the field needed sounder scientific underpinnings, particularly as we begin to take a more global and system-oriented view of our environment. Over the past several years there has been increasing concern among scientific hydrologists about the future and long-term vitality of their field. This is owing, somewhat paradoxically, to the fact that throughout the history of this field applications have preceded science. Civil and agricultural engineers are in large part responsible for the high level of water-related health and safety enjoyed by modern urban societies of the developed world. Nevertheless, this pragmatic focus has left fundamental hydrologic science lagging behind in comparison with other geosciences. The result is a scientific and educational base in hydrology that is incompatible with the scope and complexity of many current and emerging problems. Many currently important surface hydrologic problems are so large . . v''
VIll FOREWORD in scale that the land surface and atmosphere must be treated as an interactively coupled system. Examples are the environmental im- pacts of tropical deforestation, large-scale irrigation and drainage, and acid precipitation Prospects of climate change require forecast- ing based on global-scale understanding and have heightened interest in ancient hydroclimatology as revealed through paleohydrology. Contemporary ground water problems are often large scale from one to hundreds of kilometers. They involve major geological het- erogeneity and complex issues of water chemistry. Examples are the containment and reduction of pollution, underground storage of toxic waste, aquifer recharge, geothermal power production, and the conjunctive management of surface and ground water systems both at local and regional scales. The interdisciplinary nature of these problems requires increased application of principles from the atmospheric, geologic, chemical, and biological sciences; their geoscience perspective reveals impor- tant deficiencies in our basic knowledge of hydrologic science. Questions of scaling, equilibrium, stability, teleconnections, and space-time variability demand a renewed emphasis on fundamental hydrologic research. The needed understanding will be built from coordinated, long-term data sets (both at fine and large spatial scales) and founded on an educational base in the geosciences. This report should be an important reference work on opportuni- ties in the hydrologic sciences. It is intended to help guide science and educational policy decisions and to provide a scientific framework and research agenda for scientists, educators, and students making career plans. We hope it will also be of interest to the informed lay public. The document transmits the importance of the hydrologic sciences and identifies needed improvements to the research and educational infrastructure. If its recommendations are followed, we believe the strengthened scientific base of hydrology will contribute directly to improved management of water and the environment. FRANK PRESS, Chairman National Research Council
Preface Hydrologic science deals with the occurrence, distribution, circula- tion, and properties of water on the earth. It is clearly a multidisciplinary science, as water is important to and affected by physical, chemical, and biological processes within all the compartments of the earth system: the atmosphere, glaciers and ice sheets, solid earth, rivers, lakes, and oceans. Because of this geophysical ubiquity, concern for issues of hydrologic science has been distributed among the traditional geoscience disciplines. As a result, an infrastructure of hydrologic science (i.e., a distinct discipline with a clear identity and supporting educational programs, research grant programs, and research institu- tions) has not developed, and a coherent understanding of water's role in the planetary-scale behavior of the earth system is missing. This report describes this problem and offers a set of recommended remedial actions. THE PROBLEM Water moves through the earth system in an endless cycle that forms the framework of hydrologic science. In so moving, it plays a central role in many of the physical, chemical, and biological processes regulating the earth system, where human activity is now insepa- rable from natural events. Water vapor is the working fluid of the atmospheric heat engine: through evaporation and condensation it drives important atmospheric and oceanic circulations and redistrib- utes absorbed solar energy. As the primary greenhouse gas it is lX
x PREFACE instrumental in setting planetary temperature. Through fluvial ero- sion and sedimentation, water, together with tectonics, shapes the land surface. Water is the universal solvent and the medium in which most changes of matter take place; hence it is the agent of element cycling. Finally, water is necessary for life. 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. Although 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. This science, hydrologic science, has a natural place as a geoscience alongside the atmospheric, ocean, and solid earth sciences; yet in the modern scientific establishment this niche is vacant. Because of the pervasive role of water in human affairs, the devel- opment of hydrologic science has followed rather than led the appli- cations primarily water supply and hazard reductionunder the leadership of civil and agricultural engineers. The elaboration of the field, the education of its practitioners, and the creation of its research culture have therefore been driven by narrowly focused issues of engineering hydrology. The scale of understanding has been modest- generally limited to surface drainage basins with areas of 10,000 km2 or less. The committee's perception of the intellectual relationships among these water-relevant disciplines is presented in Figure 1. Hydrology has not been cultivated as a geoscience because until now there has been no practical need to build a comprehensive un- derstanding of the global water cycle. Moreover, the patches of sci- entific knowledge that support traditional small-scale engineering applications do not merge into the coherent whole needed to under- stand the geophysical and biogeochemical functioning of water at the regional and continental scales of many emerging problems. These problems include the possible geographical redistribution of water resources due to climate change, the ecological consequences of large- scale water transfers, widespread mining of fossil ground water, the effect of land use changes on the regional hydrologic cycle, the effect of non-point sources of pollution on the quality of surface and ground water at regional scale, and the possibility of changing regimes of regional floods and droughts. Furthermore, the training of hydrologic scientists cannot be ac- complished efficiently in educational programs dominated either by applications-oriented constraints or by undergraduate preparation in which engineering predominates. A thorough background in math- ematics, physics, chemistry, biology, and the geosciences is neces-
PREFACE Water Resources _ Management :' (Decision making) Xl Agriculture Economics Forestry Law Political Science . Engineering Hydrology (Forecasting) Fluid Mechanics Hydraulic Engineering Meteorology Statistics Atmospheric Science Geochemistry Geology ~ G eo morp ho lo gy Hydrologic Science ( Understanding) Plant Physiology Soil Science FIGURE 1 Water the Intellectual ingredients for its understanding, forecasting, and management. sary. New institutional arrangements will be needed to allow stu- dent and faculty involvement in relevant field observations and to provide prompt access to the resulting data. A COURSE OF ACTION One step taken to help build the needed infrastructure for hydro- logic science was the creation of the Committee on Opportunities in the Hydrologic Sciences (COHS) by the Water Science and Technology Board in January 1988. This committee was asked to conduct an assessment of the hydrologic sciences, including their definition, their current state of development, and their relationships with related geosciences and biosciences. The committee also was asked to iden- tify promising new frontiers and applications and to outline an appropriate framework for education and research in the hydrologic sciences. At the outset we should understand the committee's use of the term "geoscience" vis-a-vis "earth science" and the more recently coined "earth system science." The COHS follows the National Sci- ence Foundation (NSF) and uses "geoscience" to include atmospheric science, ocean science, solid earth science, glaciology, and, as argued herein, hydrologic science. As does the NSF, the committee interprets
. ~ Xl! PREFACE "earth science" as the solid earth sciences, including geology, petrol- ogy, seismology, volcanology, and so on. "Earth system science" includes all sciences relevant to the functioning of the planet earth as a set of interacting physical, chemical, and biological mechanisms. It differs from geoscience in its inclusion of important terrestrial biota and certain solar and other space physics effects on the earth, and in its emphasis on integrated planetary behavior. To establish an identity for hydrologic science as a separate geo- science, the COHS defined its scope to include (1) the physical and chemical processes in the cycling of continental water at all scales as well as those biological processes that significantly interact with the hydrologic cycle, and (2) the spatial and temporal characteristics of the global water balance in all compartments of the earth system. In presenting its findings the COHS has written for scientifically literate readers who are not necessarily hydrologists. We have avoided mathematics and lengthy scientific detail for the sake of clarity. The report also contains additional brief discussions of important practical problems whose solution will benefit from the anticipated scientific advances. In addition, to accent the human dimension of all scien- tific achievement, the committee has included throughout the vol- ume short biographical vignettes of important past figures in hydrol- ogy. In summary, the report's contents are as follows: Chapter 1, "Water and Life," explains the uniqueness and histori- cal importance of water. It contains examples of the roles of water in civilization both as sustainer and hazard, and as a resource to be managed. Chapter 2, "The Hydrologic Sciences," describes the evolution of the perception and definition of the hydrologic sciences and identi- fies as primary agents of change the increasing scale of applied prob- lems and the concurrent spreading of anthropogenic influences. The hydrologic cycle is recognized to be the framework of these sciences, and its physical and chemical processes are illustrated. The status of understanding of these processes and of the biological components of the hydrologic cycle is summarized. Some major research questions are posed. Chapter 3, "Some Critical and Emerging Areas," is the intellectual core of the report and contains a collection of essays on promising frontier research topics. In selecting these topics the committee has opted for the interesting and exciting, subjectively seeking to trans- mit the flavor of the science rather than to provide an exhaustive catalog of opportunities. A typical essay begins with a research question, is followed by a brief historical review, and concludes with a de- scription of the problem and its importance to the science.
PREFACE . · . XlI' The essays are grouped in sets representing the major subdivisions of the hydrologic sciences. These subdivisions reflect the major theme of this report, namely that hydrologic science is a geoscience. Ac- cordingly, the COHS looks at "Hydrology and the Earth's Crust," "Hydrology and Landforms," "Hydrology and Climatic Processes," "Hydrology and Weather Processes," "Hydrology and Surficial Processes," "Hydrology and Living Communities," "Hydrology and Chemical Processes," and "Hydrology and Applied Mathematics." There is a degree of deliberate redundancy and inconsistency in this arrangement. The quality of water is as much a part of the hydrologic cycle as is its mass or flow rate, and so chemical issues occur along with the physical in each of the geophysical subdivisions; indeed, several have been selected for presentation there. The same can be said for the mathematical topics of the final section, and, to a more limited degree, for biology. However, the committee has chosen to concentrate its discussions on the relation of hydrology to its sibling sciences in separate sections in order to call the attention of biologists, chemists, and mathematicians to interesting hydrologic problems. Chapter 4, "Scientific Issues of Data Collection, Distribution, and Analysis," discusses the need for, the characteristics of, and the cur- rent status of hydrologic data. It concludes with a set of brief essays concerning topics such as new technology, methods of analysis, and coordinated multidisciplinary experiments. Chapter 5, '`Education in the Hydrologic Sciences," contrasts ed- ucation for the internally driven puzzle solving of science with that for the externally driven problem solving of engineering. It makes specific recommendations relative to hydrologic science for programs at the graduate, undergraduate, and kindergarten through twelfth grade levels. Chapter 6, "Scientific Priorities," outlines a rational process for setting scientific priorities and presents a set of research, data, and educational opportunities that the committee believes are most important for hydrologic science at this time. Chapter 7, "Resources and Strategies," closes the report with pro- grammatic investment priorities for funding agencies, and with strategic actions that individual scientists and their scientific societies can take to enhance the image and status of hydrologic science. The report concludes with four appendixes. Appendix A gives an estimate of recent annual investments of U.S. federal agencies in re- search in hydrologic science. Appendix B profiles the hydrologic science community, contrasting the results of a 1988 human resources questionnaire with those of a similar survey published in 1962. Ap- pendix C acknowledges the many contributors to this report in addi-
xzv PREFACE lion to those listed in the front matter. Appendix D provides short biographical sketches of the members of the responsible committee. This report has been more than two years in the making. From the very beginning the committee attempted to extend its reach into the scientific community through both individual and general written invitations for contributions and through a number of public presentations of its progress. Early on the COHS recognized the need to limit its scope to a manageable subset of the myriad issues and problems related to wa- ter. We have addressed ourselves solely to hydrologic science, omitting consideration of the applied forecasting (engineering hydrology) and management (water resources) aspects of water. It is important to understand that the proposals here are not suggested as substitutes for or as pejorative reflections upon existing research or educational activities in the latter two fields but rather are intended as needed complementary, new initiatives. This report has undergone extensive review, both through the Na- tional Research Council's formal process and through various infor- mal routes. We have tried to recognize all contributors in our ac- knowledgments (Appendix C). The problem we address here is one within the infrastructure of science in the United States, and our support for this work has come solely from domestic organizations. For these reasons, and to keep the job manageable, we have not attempted the much larger task of assessing the status of the infrastructure of hydrologic science in other countries. In summary, we believe this report presents sound arguments and broad areas of action for bringing identity and unity to hydrologic science. We must succeed in this endeavor or the field will complete its fragmentation, and the other geosciences will develop and subsume the parts they need. This would likely result in a failure to generate the necessary base of water science that is coherent and complete at the large space and time scales of emerging environmental problems. PETER S. EAGLESON, Chairman Committee on Opportunities in the Hydrologic Sciences
rip Contents SUMMARY AND CONCLUSIONS Synopsis, 1 Water and Life, 2 Earth's Hydrologic Cycle, 3 A Distinct Geoscience, 4 Some Unsolved Problems, 4 Data Issues, 5 Educational Issues, 6 Scientific Priorities, 8 Resources and Strategies, 13 Conclusion, 16 1 WATER AND LIFE ............................. Wondrous Water, 17 Round and Round and Round It Goes, 18 Water as Enabler and Sustainer of Civilization, 19 Water as a Hazard, 22 Water as a Resource to Be Managed, 26 Sources and Suggested Reading, 31 2 THE HYDROLOGIC SCIENCES .......... The Uniqueness of Water on the Earth, 33 The Earth's Hydrologic Cycle, 34 The Importance of Water on the Earth, 35 Early Scientific Insights, 37 xv 1 .... 17 32
xv! i The Age of Applications, 38 The Struggle for Scientific Recognition, 40 The Modern Age of Hydrologic Science, 43 Status of Understanding, 45 Hydrologic Science as a Distinct Geoscience, 56 Sources and Suggested Reading, 60 3 SOME CRITICAL AND EMERGING AREAS. Overview, 62 Hydrology and the Earth's Crust, 67 Hydrology and Landforms, 90 Hydrology and Climatic Processes, 104 Hydrology and Weather Processes, 127 Hydrology and Surficial Processes, 142 Hydrology and Living Communities, 167 Hydrology and Chemical Processes, 178 Hydrology and Applied Mathematics, 194 Sources and Suggested Reading, 207 CONTENTS ....62 4 SCIENTIFIC ISSUES OF DATA COLLECTION, DISTRIBUTION, AND ANALYSIS 214 Need for Collection of Hydrologic Data and Samples, 215 Status of Hydrologic Data, 229 Some Opportunities to Improve Hydrologic Data, 243 Sources and Suggested Reading, 273 5 EDUCATION IN THE HYDROLOGIC SCIENCES 275 Graduate Education in the Hydrologic Sciences, 276 Structuring the Graduate Program, 280 Undergraduate Education in the Hydrologic Scicnes, 284 Science Education from Kindergarten through High School, 288 Women and Ethnic Minorities in the Hydrologic Sciences, 290 Sources and Suggested Reading, 295 6 SCIENTIFIC PRIORITIES .... 296 The Process, 296 The Premises, 297 Priority Categories of Scientific Opportunity (Unranked), 298 Data Requirements, 302 Education Requirements, 303 Sources and Suggested Reading, 303
CONTENTS RESOURCES AND STRATEGIES ..... Resources, 305 Strategies, 310 Sources and Suggested Reading, 313 APPENDIXES A. Funding for Research in the Hydrologic Sciences ..... B. Profiles of the Hydrologic Community, 1960 and 1988 C. Contributors to the Report, Opportunities in the Hydrologic Sciences .......................... D. Biographical Sketches of Committee Members INDEX......... . . XVll .. 304 317 . . . 322 . 328 331 337