I Axel Bronstert Jesus Carrera Pavel Kabat Sabine Lütkemeier Coupled Models for the Hydrological Cycle Integrating Atmosphere, Biosphere, and Pedosphere III Axel Bronstert Jesus Carrera Pavel Kabat Sabine Lütkemeier (Editors) Coupled Models for the Hydrological Cycle Integrating Atmosphere, Biosphere, and Pedosphere With 92 Figures, 19 in colour and 20 Tables IV Preface Axel Bronstert Pavel Kabat University of Potsdam Wageningen University and Institute for Geoecology Research Centre Chair for Hydrology and Climatology ALTERRA Green World Research P.O. Box 60 15 53 Droevendaalsesteeg 3 14415 Potsdam 6708 PB Wageningen Germany The Netherlands Jesus Carrera Sabine Lütkemeier Technical University of Catalonia (UPC) Potsdam Institute for Department of Geotechnical Engineering Climate Impact Research and Geosciences Telegrafenberg School of Civil Engineering 14473 Potsdam Campus Nord, Edif. D-2 Germany 08034 Barcelona Spain Library of Congress Control Number: 2004108318 ISBN 3-540-22371-1 Springer Berlin Heidelberg New York This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifi cally the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfi lm or in any other way, and storage in data banks. Duplication of this publication or parts thereof is permitted only under the provisions of the German Copyright Law of September 9, 1965, in its current version, and permission for use must always be obtained from Springer. Violations are liable to prosecution under the German Copyright Law. Springer is a part of Springer Science+Business Media springeronline.com © Springer-Verlag Berlin Heidelberg 2005 Printed in Germany The use of general descriptive names, registered names, trademarks, etc. in this publication does not imply, even in the absence of a specifi c statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. Cover design: Erich Kirchner Production: Almas Schimmel Typesetting: PR-Graphix, Karl C. Stahl, Heidelberg Printing: Mercedes-Druck, Berlin Binding: Stein + Lehmann, Berlin Printed on acid-free paper 30/3141/as - 5 4 3 2 1 0 V Preface Freshwater resources are an indispensable part of all terrestrial ecosystems. The Dublin Statement on Water and Sustainable Development states: “Scarcity and misuse of fresh water pose a serious and growing threat to sustainable development and protection of the environment. Human health and welfare, food security, industrial development and the ecosystems on which they depend are at risk, unless water and land resources are managed more effectively in the present decade and beyond than they have been in the past“. Similarly, the fi rst principle defi ned at the Dublin Conference states “Fresh water is a fi nite and vulnerable resource, essential to sustain life, development and the environment“ (UNESCO 1996). Strategies for sustainable development must be based on an accurate assessment of the Earth‘s carrying capacity and resilience to human activity. A deeper understanding of the interconnections between water, nutrient and biogenic cycles, and the energy fl ows of land, oceans and atmos phere, is crucial (UNCED 1992). AGENDA 21 calls for an “Integrated Approach to Land- Resource Use, and Protecting and Managing Freshwater Resources“. Increasing demand for land – a fi nite resource – and for the natural resources land supports is creating competition and confl ict that results in land degradation. The Framework and General Outline of IHP-V (www.unesco.org/water/ ihp/) states that if future water resource develop ment and management schemes are to be sustainable, they will have to deal effectively with environmental and social consequences; land-water link ages; allocation of water among competing uses and users; and achieving effective imple mentation. To achieve these goals, four areas of concern need addressing: 1. the role of scales in hydrological processes; 2. vulnerability of the environ ment; 3. integrated water resource management; and 4. education, training and transfer of technologies. VI Preface IHP Project 1.2 addresses the fi rst two, in particular, fostering the development of coupled hydroecologi cal/atmospheric models, synthesising hydrological data relevant to the calibration of those models and identifying the effects of enhanced atmospheric carbon dioxide. However, it is important to keep the last two goals in mind in order to stimulate stronger interactions between research, education and application and to emphasise integrated resource management and science. The International Dialogue on Water and Climate (DWC) aims to improve interactions between climate scientists and the water resource management. DWC (www.waterandclimate.org) bridges the information gaps between the water and climate sectors to improve our capacity to cope with the impacts on water management of increasing climate variability and change. The goal of the Dialogue is to develop a knowledge base, generate widespread awareness, identify policy and management options that build such capacities, learn from the experiences throughout the world, and make this knowledge available to the most affected communities. In general, coupled models are developed in pursuit of a particular objective and will therefore always have bias towards particular processes and phenomena. Similarly, this document is deliberately biased to place greater emphasis on hydrological processes and less emphasis on processes elsewhere in the coupled system. Later, for instance, when the interrelationships between processes is explored, processes and phenomena in the hydrological system are diagnosed in greater detail than are atmospheric, land-cover and transport processes. Further, to focus more on land-surface hydrological/atmospheric coupling, the domain of interest considered is limited to coupling processes relevant at the spatial scale of regions or large catchments. It is assumed, therefore, that either the incoming and outgoing atmospheric fi elds around the continental domains are measured or, if they are calculated elsewhere in a global coupled model, that the coupling between oceans and the atmosphere has been represented adequately. When modelling the hydrological system, it is not always necessary that all (or indeed any) coupling processes be represented. There are, however, at least four general situations where the use of coupled models is essential, as follows. • It is not feasible or economic to measure the boundary between com- partments in the modelled hydro-geo-biosphere system and thereby isolate them. This will be common when models are being used in truly predictive mode. VII • Observations of two or more state variables that are coupled cannot be modelled simultaneously unless the processes that couple them are in- cluded in the model. Sometimes, for instance, this is the case for models that describe the fl ows not only of water quantity but also of the chemi- cal composition of that moving water simultaneously. Representing both with a coupled model can reveal hitherto unrecognised weaknesses in the uncoupled description of water fl ow. • The science that is being addressed is beyond the normal range of ac- tivity and interest of specialists in individual coupled processes. In this case, the discipline of developing a coupled model can often produce totally new scientifi c understanding that would not otherwise have been possible. • Vulnerability assessments of the whole system are undertaken. This book is intended primarily for applied scientists and graduate students. It should also become a valuable source of information for hydrology and water resource management professionals who wish to advance their knowledge of the key principles of the coupled climate- hydrology system, and to use water system management models. As such, this book will be a valuable help in education and training. Mike Bonell, Axel Bronstert, Pavel Kabat, Jim Shuttleworth Agenda 21 (1993) Programme of action for sustainable development. Rio declaration on environment and development. The fi nal text of agreements negotiated by governments at the United Nations Conference on Environment and Development (UNCED), 3 - 14 June 1992, Rio de Janeiro, Brazil. New York, NY: United Nations, p 294 UNCED (1992) Report of the United Nations Conference on Environment and Development: Rio de Janeiro, 3 - 14 June 1992, New York, United Nations publication VIII Preface Acknowledgements The Editors would like to express their sincere thanks to the International Hydrology Programme (IHP) of UNESCO, to the former Core Project of the International Geosphere-Biosphere Programme “Biospheric Aspects of the Hydrological Cycle (BAHC)” and to the Dialogue on Water and Climate (DWC). All these three international programmes helped in convening workshops for the authors or in providing funding to fi nalise the book for publication. We are grateful to the German Federal Ministry of Education and Research (BMBF) for fund ing the BAHC Project Offi ce at the Potsdam Institute for Climate Impact Research (PIK). The Dutch Ministry of Development Cooperation provided support through the DWC. Additional funding and support have been provided by the German IHP-HWRP (Hydrology and Water Resources Programme of the WMO) Committee. We also wish to thank Ursula Werner (PIK) for converting most of the fi gures and Andreas Bauer (University of Potsdam) for additional technical support. Cover design: River