Next to air, water is the most essential of human requirements. The hydrosphere-the waters of the Earth, its oceans, rivers and lakes-is vital, constituting a feature unique in the solar system and one responsible for physical and climatic phenomena characteristic of the planet. Water moves through the hydrologic cycle and runs the heat engine of the Earth, approximately 97% of it occurring in the oceans. These contain vast natural resources including abundant plant and animal life and they assist in cleansing the atmosphere by becoming the final repository of air and land pollutants of which many are man-made. Unfortunately their ability to do this is diminishing because of rising pollution by toxicants such as DDT, nuclear by-products such as strontium-90 and oil spills. The oceans contain huge quantities of various substances mostly originating from the atmosphere, biological activity, river transport after rock weathering, groundwater, spreading zones along mid-oceanic ridges and crustal out-gassing. After hydrogen and oxygen, the commonest elements in them are Cl, Na, Mg, S, K, Ca, Br, C and B. The atmosphere and the oceans together cooperate in an energy cycle important in controlling and equalising the Earth's surface temperature.

The Workshop on Parameter Identification and Inverse Problems in Hydrology, Geology and Ecology, Karlsruhe, April 10-12, 1995, was organized to bring to gether an interdisciplinary group drawn from the areas of science, engineering and mathematics for the following purposes: - to promote, encourage and influence more understanding and cooperation in the community of parameter identifiers from various disciplines, - to forge unity in diversity by bringing together a variety of disciplines that attempt to understand the reconstruction of inner model parameters, un known nonlinear constitutive relations, heterogeneous structures inside of geological objects, sources or sinks from observational data, - to discuss modern regularization tools for handling improperly posed pro blems and strategies of incorporating a priori knowledge from the applied problem into the model and its treatment. These proceedings contain some of the results of the workshop, representing a bal anced selection of contributions from the various groups of participants. The reviewed invited and contributed articles are grouped according to the broad headings of hydrology, non-linear diffusion and soil physics, geophysical methods, mathematical analysis of inverse and ill-posed problems and parallel algorithms for inverse problems. Some of the issues adressed by the articles in these proceedings include the rela tion between least squares and direct formulations of inverse problems for partial differential equations, nonlinear regularization, identification of nonlinear consti tutive relations, fast parallel algorithms for large scale inverse problems, reduction of model structures, geostatistical inversion techniques.

ACKNOWLEDGEMENTS IX PART I CONFERENCE SUMMARY STATEMENT R. W. BROCKSEN, W. CHOW, E. D. DAUGHERTY, Y. G. MUSSALLI, J. WISNIEWSKI and A. L. WOODIS I Clean Water: Factors that Influence its Availability, Quality and its Use: Summary of the International Water Conference 3-7 PART II WATER RESOURCE OVERVIEWS S. PECK I Managing and Protecting Our Water Resources 11-20 R. BROCKSEN, W. CHOW and K. CONNOR I Addressing Electric Utility Surface Water Challenges 21-29 C. LOHSE-HANSON I Lake Superior Binational Program: The Role of Electric Utilities 31-40 J. A. VEIL and D. O. MOSES I Consequences of Proposed Changes to Clean Water Act Thermal Discharges 41-52 PART III ECOLOGICAL I HEALTH RISKS c. SEIGNEUR, E. CONSTANTINOU and L. LEVIN I Multipathway Health Risk Assessment of Power Plant Water Discharges 55-64 C. W. CHEN, J. HERR, R. A. GOLDSTEIN, F. J. SAGONA, K. E. RYLANT and G. E. HAUSER I Watershed Risk Analysis Model for TVA's Holston River Basin 65-70 S. FERSON, L. R. GINZBURG and R. A. GOLDSTEIN I Inferring Ecological Risk from Toxicity Bioassays 71-82 C. ARQUIETT, M. GERKE and I. DATSKOU I Evaluation of Contaminated Groundwater Cleanup Objectives 83-92 G. L. BOWIE, J. G. SANDERS, G. F. RIEDEL, C. C. GILMOUR, D. L. BREITBURG, G. A. CUTIER and D. B. PORCELLA / Assessing Selenium Cycling and Accumulation in Aquatic Ecosystems 93-104 D. W. RODGERS, J. SCHRODER and L.

This text is the first international and comprehensive discussion of the impacts of climatic fluctuations and climate change on water resources management. The book presents an overview of the impacts of climatic change/fluctuations on a wide variety of water resources sectors including river runoff, water quality, water temperature, water use and demand, reservoir management and water resource planning and management. The book is unique in that it then presents a series of case studies to both demonstrate the application of climate change impact assessment methodologies and to provide insights to catchment, river basin, and national scale impacts of climate change/fluctuations on the water resources of Africa, Europe, and North America. Audience: Researchers, scholars and students of hydrology and water management who are concerned with the issues of climate change as well as the climate change impact assessment community.

The irrigated area in the Aral Sea basin totals about 7. 5 million hectare. Part of the water supplied to this area is consumed by the irrigated crop; the remainder of the supplied water drains to the groundwater basin, to downstream depressions, or back to the rivers. During its use, however, this drained part of the water accumulates salts and chemicals. The disposal of this polluted water causes a variety of (environmental) problems. If the percentage consumed water of the total water supply to an irrigated area (the so-called overall consumed ratio) can be increased, less water needs to be drained. This alleviates part of the related (environmental) problems. Further, if the overall consumed ratio for the above 7. 5 million hectare is improved, less water needs to be diverted from the rivers. Hence, more water can flow towards the Aral Sea. As mentioned above, part of the non-consumed irrigation water drains to the groundwater basin. Commonly, the natural discharge capacity of this basin is insufficient to handle this imported water. As a result, the groundwater table rises towards the land surface causing waterlogging. In (semi-)arid zones this waterlogging triggers a soil salinity problem resulting to a significant reduction in crop yields. The artificial increase of the discharge capacity, and lowering of the groundwater table, solves the soil salinity problem.

Shortly after the creation of the Vrije Universiteit Brussel (Free University Brussels) in 1970, currently labelled as VUB, a Department of Quaternary Geology was installed within the Faculty of Science in 1974. At the beginning it dealt mainly with the study of periglacial loess deposits of the Pleistocene Glacial Period in Central Belgium and with coastal deposits in relation to sea level rise during the warm Holocene period covering the last 10,000 years, in which the dawn of civilization took place step by step. Today the same research teams widen their scope of interest: they are presently studying the loess plateau in the People's Republic of China and the world-wide problems associated with sea level rise, coastal erosion being one of the most devastating natural hazards. More and more emphasis is put on problems concerning environmental engineering and those dealing with global change. Since 1975 UNESCO sponsored a number of symposia of the International Union for Quaternary Research (INQUA), whose secretariat was located on the VUB Campus grounds from 1973 to 1982. In 1981 the Applied Geology Department ofthe Faculty of Applied Sciences was created. The NATO-Advanced Research Workshop (ARW) , organized in Fuerteventura (Canary Islands, Spain) in March 1989 was a climax of this series of Global Change gatherings. As Rector of the VUB, I am satisfied that the VUB, through its Earth Technology Institute, of both USA and Belgium could cooperate with NATO and the National Science Foundations in cosponsoring such an initiative.

The protection of groundwater resources has emerged in recent years as a high priority topic on the agenda of many countries. In responding to the growing concern over deteriorating groundwater quality, many countries are developing a comprehensive regulatory framework for the management of subsurface water resources with management referring to both quantity and quality aspects. Within this framework, groundwater models are rapidly coming to playa central role in the development of protection and rehabilitation strategies. These models provide forecasts of the future state of the groundwater aquifer systems and/or the unsaturated zone in response to proposed management initiatives. For example, models will predict the effects of implementing a proposed management scheme on water levels and on the transport and fate of pollutants. The models are now used in the formulation of policies and regulations, the issuing of permits, design of monitoring and data collection systems, and the development of enforcement actions. The growth in the use of these sophisticated tools has led to many unforeseen problems in groundwater management. Lingering issues include reliability of codes, quality assurance in model development and applications, efficient utiliza tion of human and material resources, technology transfer and training. Some issues have legal ramifications, as in cases where the applications of models have been contested in courts."

Storage reservoirs represent one of the most effective tools for eliminating, or at least for minimizing, discrepancies in the time and space variations of water resources distribution and requirements. In fact, the different - often contradictory - and increasing demands on water resources utilization and control usually can be fulfilled only by building multi-purpose reservoir systems. In this way, the available water resources can be exploited and/or managed in a more rational way. Typically, the construction of a dam across a river valley causes water to accumulate in a reservoir behind the dam; the volume of water accumulated in the reservoir will depend, in part, on the dimensions of the dam. The size of the dam will normally affect the capital expenditure in a very significant way. Indeed the construction of large water resource control systems - such as dams - generally involves rather huge manpower and material outlays. Consequently, the elaboration of effectual methods of approach that can be used in establishing the optimal reservoir parameters is of great practical significance. For instance, in the design and operation oflarge multi-reservoir systems, simple simulation and/or optimization models that can identify potentially cost effective and efficient system design are highly desirable. But it should be recognized that the problem of finding optimal capacities for multi-reservoir systems often becomes computationally complex because of the large number of feasible configurations that usually need to be analyzed."

This volume contains the lectures presented at the NATO ADVANCED STUDY INSTITUTE that took place at Newark, Delaware, U. S. A. , July 14-23, 1985. The objective of this meeting was to present and discuss selected topics associated with transport phenomena in porous media. By their very nature, porous media and phenomena of transport of extensive quantities that take place in them, are very complex. The solid matrix may be rigid, or deformable (elastically, or following some other constitutive relation), the void space may be occupied by one or more fluid phases. Each fluid phase may be composed of more than one component, with the various components capable of interacting among themselves and/or with the solid matrix. The transport process may be isothermal or non-isothermal, with or without phase changes. Porous medium domains in which extensive quantities, such as mass of a fluid phase, component of a fluid phase, or heat of the porous medium as a whole, are being transported occur in the practice in a variety of disciplines.

Advances in computer technology, in the technology of communication and in mathematical modelling of processes in the hydrological cycle have recently improved our potential to protect ourselves against damage through floods and droughts and to control quantities and qualities in our water systems. This development was demonstrated in a 1983 post-experience course at Wageningen University where an international group of experts reviewed successful modelling techniques and described the design and operation of a number of forecasting and control systems in drainage basins and river reaches of various sizes and under various geographical and climat ological conditions. A special effort was made to bridge the gap between theory and practice; case studies showed that each forecasting system was designed to meet a set of specific requirements and they illustrated that the forecasting system can only be expected to operate reliably if, on the one hand, it is based on sound theoretical concepts and methods and if, on the other hand, it is robust so that, also under adverse conditions, it will continue to collect and process the necessary input data and produce correct and timely signals. We were pleased to meet with encouragement for preserving the course material and making it available to a wider public. This was effected by the team of authorf who elaborated, updated and harmonized the materia in two stages; first into an issue of our university department and finally into the manuscript of this book."

The Fourth American Physical Society Topical Conference on Shock Waves in Condensed Matter was held in Spokane, Washington, July 22-25, 1985. Two hundred and fifty scientists and engineers representing thirteen countries registered at the conference. The countries represented included the United States of America, Australia, Canada, The People's Repub lic of China, France, India, Israel, Japan, Republic of China (Taiwan), United Kingdom, U. S. S. R, Switzerland and West Germany. One hundred and sixty-two technical papers, cov ering recent developments in shock wave and high pressure physics, were presented. All of the abstracts have been published in the September 1985 issue of the Bulletin of the American Physical Society. The topical conferences, held every two years since 1979, have become the principal forum for shock wave studies in condensed materials. Both formal and informal technical discussions regarding recent developments conveyed a sense of excitement. Consistent with the past conferences, the purpose of this conference was to bring together scientists and engineers studying the response of condensed matter to dynamic high pressures and temperatures. Papers covering experimental, theoretical, and numerical studies of con densed matter properties were presented. A noteworthy feature of this conference was the participation by several leading scientists engaged in static high pressure research. Donald Curran served as the Master of Ceremonies at the conference banquet, which was at tended by two hundred and seventy-five conference participants and guests including Dr. Samuel Smith, the new President of Washington State University. Dr.

For centuries, physical models have been used to investigate complex hydraulic problems. Leonardo da Vinci (1452-1519) stated, "I will treat of such a subject. But first of all, 1 shall make a few experiments and then demonstrate why bodies are forced to act in this matter. " Even with the current advancements of mathematical numerical models, certain complex three-dimensional flow phenomena must still rely on physical model studies. Mathematical models cannot provide adequate solutions if physical processes involved are not completely known. Physical models are particularly attractive to investigate phenomena-involved sediment movements because many three-dimensional sediment processes are still unclear at this stage. Theoretically, there are numerous factors governing movable bed processes and it is nearly impossible to design model studies to obey all the model criteria. Sometimes, appropriate lightweight materials are difficult or too costly to obtain. Often, distorted models are used due to the limitation of available space and the requirement for greater vertical flow depth to investigate vertical differences of various parameters. The turbulence level in the model may also be maintained at a sufficient level to reproduce a similar flow pattern in the prototype. Frequently, engineers are forced to employ distorted models that cannot be designed to satisfy all governing criteria correctly. Thus each hydraulic laboratory has developed its own rules for model testing and a great deal of experience is needed to interpret model results.

Causes of major disasters are many and diverse, and the risks associated with them endanger human lives, property, the environment, the economy, and even the country's political and social well-being. It is clear that, with rapid population growth, environmental degradation, climate change, poorly regulated industries, and continued economic uncertainty, the chances are that communities may become more vulnerable to disasters. The dramatic losses in recent years from volcanic eruptions, earthquakes and landslides, wildland fires, droughts and floods, cyclones and storm surges attest to the fact that we are still a long way from applying even the knowledge we have today to make communities safe. Tackling this problem requires a sound evaluation of disaster mitigation policies and tools. As a contribution to the International Decade for Natural Disasters Reduction (IDNDR), the fifth international symposium HAZARDS-93 was held in Qingdao, P.R. China on 29 August - 3 September, 1993. China is a country frequently hit by almost all kinds of disasters. Its history is one of combating natural disasters and working towards their reduction. More than 250 scientists, engineers and government officials from 20 countries met for the purpose of engaging in a free exchange of knowledge, experience and ideas regarding the scientific and socio-economic aspects of mitigating losses from natural and man- made disasters. A total of 180 papers were presented at 28 sessions covering a very broad range of topics related to disaster management. The twenty-one articles included in this book deal with the scientific and management issues of land-based and marine hazards which cause the most severe economic losses, deaths and environmental degradation in many parts of the world. The book also includes specific recommendations addressed to the IDNDR Secretariat, national governments and scientific experts to increase the effectiveness and efficiency of disaster management. Thus, Land-Based and Marine Hazards: Scientific and Management Issues forms an excellent reference for scientists, engineers, policy-makers and the insurance industry.

1. Provides cutting edge AI applications in water sector. 2. Highlights the environmental models used by experts in different countries. 3. Discusses various types of models using AI and its tools for achieving sustainable development in water and groundwater. 4. Includes case studies and recent research directions for environmental issues in water sector. 5. Addresses future aspects and innovation in AI field related to water sustainability.

The International Hydrological Decade (which ended in 1975) led to a revival of hydrological sciences to a degree which, seen in retrospect, is quite spectacular. This research programme had strong government support, no doubt due to an increased awareness of the role of water for prosperous development. Since water quality is an essential ingredient in almost all water use, there was also a considerable interest in hydrochemistry during the Decade. As many concepts in classical hydrology had to be revised during and after the Decade there was also a need for revising hydrochemistry to align it with modern hydrology. A considerable input of fresh knowledge was also made in the recent past by chemists, particularly geochemists, invaluable for understanding the processes of mineralization of natural waters. With all this in mind it seems natural to try to assemble all the present knowledge of hydrochemistry into a book and integrate it with modern hydrology as far as possible, emphasizing the dynamic features of dissolved substances in natural waters. Considering the role of water in nature for transfer of substances, this integration is essential for proper understanding of processes in all related earth sciences. The arrangement of subjects in the book is as follows. After a short introductory chapter comes a chapter on elementary chemical principles of particular use in hydrochemistry.

This volume certainly is a Conference Proceedings, the Proceedings of the NATO Advanced Research Workshop (ARW) on "Unsaturated Flow in Hydrologic Modeling" held at "Les Villages du Soleil" near ArIes, France from June 13 to 17, 1988. Let me therefore acknowledge properly, at the very beginning, the gratitude of all the participants to the NATO Science Committee for its generous support and worthwhile goal of bringing together scientists of many countries to communicate and share their experiences. Particular thanks are extended to the director of the program, Dr. Luis Vega da Cunha for his interest and understanding. On the other hand this volume is also, and probably more so, a Textbook that fills a gap in the field of unsaturated flow. Many treatises on the subject present the theory in its different aspects. Hardly any explain in details how the different pieces can be put together to address realistic problems at the basin scale. The various invited contributions to the ARW were structured in a subject progression much as chapters are organized in a book. The intent of the ARW was to assess the current state of knowledge in "Unsaturated Flow" and its use in "Hydrologic Modeling Practice." In a sense the interest in fundamentals of unsaturated flow in this ARW was not just for the sake of knowledge but also and primarily for the sake of action. Can such fundamental knowledge be utilized for better management of the water resource? was the basic question.

The completion of this collection took many months, and, for a variety of reason, required the assistance and/or indulgence of a number of individuals. First and foremost, I would like to thank Tim Hudson for his useful input and support at the outset of the project Likewise, I would like to thank Jesse O. McKee for providing a hospitable environment during my affiliation with the University of Southern Mississippi. At Louisiana State University I am grateful to Sam Hilliard and Carville Earle for their invaluable understanding. The book became part of the GeoJoumal Library as a result of Wolf Tietze's confidence in the topic, and because of Henri G. van Dorssen's (and Kluwer Academic Publishers') good nab.lre - despite numerous 'problems'. Curtis C. Roseman, and the remainder of the Geography Department at the University of Southern California (where I completed many last minute details for the volume), are to be thanked for the cordial and warm environ ment I received while a visitor in Los Angeles. Finally, no multi-authored collection reaches completion without the help of many patient contributors. This particular book suffered many set-backs along the way, so I am particularly grateful to the authors herein. They demonstrated their compassion and exceptional professionalism throughout, by never second-guessing my decisions, and by allowing me to remedy the set-backs in my own way. They were a pleasure to work with, and they should take pride in their achievements."

Trans-boundary water resources are often a cause of conflict among riparian entities. Increasing demand for water resources and deterioration of existing water sources underscore the need to resolve conflicts over the allocation of consumption and pollution rights among conflicting uses and users. Because economic growth of the entities that share a water resource depends on sustainability of the resource, water has great potential as a basis for cooperation among political entities. However, enforcement of cooperation particularly in international settings is limited. Thus, parties sharing a water resource will form and remain in a cooperating coalition only when economic incentives for each can be identified. This book offers an economic approach to resolution of conflicts by identifying economic mechanisms that encourage sustainable cooperation. The book includes discussions on international, interstate, and intrastate disputes regarding both water quantity and water quality issues. It presents mechanisms for facilitating cooperation among users from agricultural, industrial, domestic, and environmental sectors.It considers the experience and potential in many regions around the world including Australia (the Muray-Darling Basin), Latin America (Chile), the Middle East (Israel and the Palestinian Authority), the U.S. (California, Florida's Everglades, Hawaii, and the Chesapeake Bay), and Africa (South Africa, Lesotho). Part I of the book discusses international experience in forming water coalitions and offers an illustrative model of water quality coalitions. It emphasizes the dependence of sustainability of international agreements on the practical ability to create incentives through economic mechanisms and political linkages that overcome the problem of limited enforcement due to sovereignty claims. Part II of the book discusses management of intrastate U.S. water resources involving competing local jurisdictions or user groups and the U.S. and Australian attempts to facilitate state management of interstate water resources through federal cooperation. Part III of the book explores the expanding scope of trans-boundary water resource issues that contribute to complexity of conflict beyond traditional interests such as allocation and navigation rights.In particular, it analyzes the economic implications of nutrient, land, and airshed management in an environment where the interaction of trans-boundary water resources with the ecological system is considered. Trans-boundary water usage and infrastructure are discussed in the context of privatization and political uncertainty. Part IV of the book examines economic solutions to trans-boundary water allocation including water markets, tradable water permits, contractual arrangements, and coordinated management. The interaction between ground and surface water and the interaction between desalinated, recycled, and fresh water is analyzed in the context of optimal water allocation. The book concludes with a critical discussion of the role and potential of the economics profession in contributing to conflict resolution and management of trans-boundary water resources. The strengths and weaknesses of economic analysis are discussed with special consideration of the modern tools of bargaining theory and game theory that go beyond economic efficiency in considering political realities.

THE STUDY OF THE BIOSPHERE The term 'biosphere' first appeared in the works of the French biologist 1.-B. Lamarck and the Austrian geologist E. Suess in the 19th century. In the 20th century, the study of the biosphere attracted considerable attention, largely due to the research of V. I. Vernadsky (1863- 1945). The results Qf Vernadsky's investigations have appeared in a number of publications, including the monograph The Biosphere published in 1926. This work consists of two parts, The Biosphere in Cosmos' and The Zone of Life', written in a form of speculation and reflection that is rarely used in modern studies. This work concerns the distinguishing properties of the space occupied by organisms and the exceptional importance of the activities of these organisms in the formation of their environment. In this and subsequent studies, Vernadsky has laid the foundations of the science of the biosphere, which today plays an important role in th.c many branches of science concerned with the Earth. Several terms have been suggested for the science of the biosphere, including global ecology (a discipline studying the global ecological system, whose meaning is close to that of the biosphere). One of the most prominent predecessors of Vernadsky was his teacher V.

"Field screening" indicates field analytical tools, and (quick) methods and strategies for on-site or in-situ environmental analysis and assessment of contamination. "Field screening" includes not only field analytical methods, such as mobile laboratories, portable analyses, detectors, sensors, or noninvasive techniques, but also reconnaissance strategies and problems of measurement in heterogeneous media, using, among others, new geotechnical and geophysical instruments.

This volume contains both oral and poster contributions to the Second International Conference on Strategies and Techniques for the Investigation and Monitoring of Contaminated Sites, "Field Screening Europe 2001," held in Karlsruhe, May 14 - May 16, 2001. As an integrated study of environmental contamination, "field screening" has become a more and more important part of environmental monitoring and the assessment of chemical contaminations. Recent developments are presented in these proceedings.

Audience Environmental engineers, geo-scientists, chemists, biologists, soil scientists, hydrologists and geophysicists.

The well documented history of pollution and recovery in the Thames Estuary has made the system one of the world's most famous case studies. However, the story is incomplete in terms of the status of the rehabilitated ecosystem resulting from the remedial management policies. What ecosystem might we expect to recover from a once lifeless estuary? have the extensive efforts made by policy makers, environmental managers and scientists resulted in a diverse, complex estuary that may be a model for other systems? This book draws together many detailed aspects of the recovering Thames Estuary ecosystem from environmental management and scientific sources. The result is probably the most comprehensive account of the management and ecology of a single estuarine system yet produced. It includes important and extensive long term studies of the fish communities, water quality and management policy, spatial accounts along the full length of the estuary for benthic invertebrates and algae, significant case studies on zooplankton, saltmarshes and parasitology, as well as an overview looking forward to the next millennium.Altogether, this study of the long term ecological consequences of management policy provides a benchmark for comparison with other estuarine ecosystems, both 'natural' and rehabilitated, and forms a unique and valuable reference for environmental managers, estuarine scientists and ecologists.

Interest in water will continue to grow for a long time to come. It will continue to spread over a large number of disciplines and technologies. Research into water in all its aspects has become so diverse that even those with a direct interest find it impossible to keep up with the original literature beyond a very limited range. On the other hand, scientists want to keep in touch with a wide spectrum of basic and applied research on water and the role played by aqueous solvents in physical, chemical, biological, technological and environmental processes. Water Science Reviews contains three or four critical reviews of the type previously published in the seven volume work Water - A Comprehensive Treatise. Some reviews update previously published topics, while others feature areas of Water Sciences that have never yet been reviewed. A common focus is the central position adopted by water in the systems and processes described.

In diamond alluvial deposits, the information about the spatial distribution of stone size is of crucial importance for the quantitative characterisation of the different areas of the deposit. In fact, the value of the diamond reserves depends strongly on the distribution of stone sizes: between two areas with the same grade, the most valuable is the one with larger stones. The geological genesis of the mineralization, related with the transport and deposition of stones in trapsites, can create separated spatial areas, corresponding to different stone size. To characterise these distinct areas, the non smooth transitions between them should be accounted for, in the estimation of internal properties. An extended version of zonal control of geostatistical estimation (Soares et ai, 1995) proposed in this paper, aims to characterising the classes of size histogram for each geological unit, avoiding the smooth effect. For this purpose the morphology of each geological unit is obtained by using two distinct criteria: i) first, the points of each unit are classified according to the local and global probabilities of belonging to each unit (Soares, 1992); ii) in a second classification, the optimization technique of Simulated Annealing is used to rearrange the pre-classified points in order to impose, in the final morphological maps, the spatial variability of experimental samples (Goovaerts, 1994). A case study of a diamond alluvial deposit with two geological units with distinct stone size histograms is presented.

This volume describes important sites in the Pleistocene deposits of the Thames terrace system laid down by the Thames and its tributaries. It correlates the Thames sequence with deposits found elsewhere in Britain, on the European continent and on the ocean floor.

The majesty of the icefields is beyond description. He who has been fortunate to be there once, remains bound forever. To a theoretical physicist working on black holes the icefields produce a familiar vertigo, the instinctive certainty of being confronted with something so simple and beautifully extreme that it must be of importance. The meeting whose proceedings are contained in this volume was conducted onboard of a vessel that went to the icefields, and the participants could literally set foot on them. It was expected that, for those who had not been there before, this would constitute a ritual of initiation. And so it did. For this reason we like to refer to the meeting as an expedition because, although it did not have the hardship, it had the spirit. After this foundational expedition there have been two others, this time both with spirit and hardship, one from Chile and one from Argentina. At the moment of this writing, a fourth, full-fledged airborne expedition to the icefields is about to depart from Valdivia. Many of the people of many nations who were on board of the Aquiles will take part in it. We look forward to its results, and to an ongoing exciting scientific adventure. Claudio Teitelboim Director, Centro de Estudios Cientfficos Valdivia, September 2001 v ACKNOWLEDGMENTS This volume is the result of the effort and generosity of many people and institutions.