The biennial International Gothenburg Symposia on Chemical Water and Waste water Treatment have proven to be a unique platform for the exchange of ideas and experiences between administrators, engineers and scientists active in the fields of water supply, wastewater disposal and pollution control. The First Symposium (Gothenburg, 1984) provided a long needed survey over theory and application of chemical water and wastewater treatment. The Second Symposium (Berlin, 1986) was devoted to aspects of recycling in chemical water and wastewater technology. The Third Symposium (Gothenburg, 1988) recognised the growing need and the potentials of pretreatment. These proceedings of the 4th Symposium focus on technology transfer from chemical treatment theory to practical treatment of drinking water and industrial or domestic wastewater. The contributions are devoted to questions of floc for mation and floc separation as well as problems and practical solutions associated with chemicals and dosing control. Special attention is given to the combination of chemical and biological processes for nutrient removal from wastewater. It is the editors' privilege to acknowledge the invaluable help from the authors of this book. It is the editors' hope that they might convey the significance and potential of chemical treatment in solving the challenging problems water purification, wastewater disposal and pollution control.

Climate modelling is a field in rapid development, and the fltudy of cryospheric processes has become an important part of it. On smaller time scales, the effect of snow cover and sea ice on the atmospheric circulation is of concern for long-range weather forecasting. Thinking in decades or centuries, the effect of a C02 climatic warming on the present-day ice sheets, and the resulting changes in global sea level, has drawn a lot of attention. In particular, the dynamics of marine ice sheets (ice sheets on a bed that would be below sea level after removal of ice and full isostatic rebound) is a subject of continuous research. This interest stems from the fact that the West Antarctic Ice Sheet is a marine ice sheet which, according to some workers, may be close to a complete collapse. The Pleistocene ice ages, or glacial cycles, are best characterized by total ice volume on earth, indicating that on 4 5 large time scales (10 to 10 yr) ice sheets are a dominant component of the climate system. The enormous amount of paleoclimatic information obtained from deep-sea sediments in the last few decades has led to a complete revival of iriterest in the physical aspects of the Pleistocene climatic evolution.

The fundamental principles of tephrochronology were de- veloped in Iceland through the classic research of Professor Sigurdur Thorarinsson in the 1940's and 1950's. By his studies on the volcanic ash layers (tephra) produced by the historic explosive eruptions of the volcano Hekla, he established that individual tephra layers could be correlated over large areas of Iceland. As the deposition of such layers was essentially instantaneous on a geological time-scale, the tephra layers provided a distinctive and widespread isochronous stratigraphic marker. Since Thorarinsson's pioneering work, the study of tephra has become a powerful and increasingly important research tool in many branches of the geological sciences and related disciplines. In response to the recent rapid growth and diversifica- tion of tephra studies we decided to coordinate a NATO Advanced Studies Institute under the auspices of the INQUA Commission on Tephra. The ASI, entitled "Tephra Studies as a Tool in Quaternary Research," was held from June 18th to June 29th, 1980, at Laugarvatn in Iceland. This book represents the proceedings of that Institute and is the first book dedicated to tephra studies, its many uses and applications. The subject matter combines disciplines as diverse as Quaternary strati- graphy, isotope geochronology, petrology, deep-sea geology, volcanology, volcanic hazards mapping, archaeology and ecology in one volume, and illustrates both present uses and future potential of tephra research.

Most water systems in the industrial regions of the world are already developed. At the same time they are highly complex. This is true with respect to physical configuration, managment, operation, political goals, environmental interactions, etc. Thus the basic systems are already in place. This realization is the starting point for any new water developments and for operation. From this we conclude that whatever we do to meet new exigencies requires an understanding of the presently in-place complex water systems. Their operation is the important thing. And how can we adjust their operation to meet the new demands upon the system? This book deals with complex water systems and their operation. Some chapters are highly theoretical while others are rooted in practical applications. How can we an lyze the operation of a complex water system and determine how its performance can be improved? Several chapters on mathematical analysis give approaches involving different aspects of this problem. But operation also has political, management, and physical aspects. These problems are addressed in chapters by managers who operate such systems. The main theme of all chapters is how to deal with the different aspects of a complex water system, already in place. We feel the book, in dealing with this question could be a start for new theoretical premises in water planning.

This book presents a systematic approach to understanding and applying the principles of hydrology and hydroclimatology, examining the interactions among different components of the water cycle. It takes a fresh look at the fundamentals and challenges in hydrologic and hydroclimatic systems as well as climate change. The author describes the application of nontraditional data sets and new investigation techniques to water-related problems. He also examines long lead forecasting and simulation, time series analysis, and risk and uncertainty in hydrologic design.

Floods constitute a persistent and serious problem throughout the United States and many other parts of the world. They are responsible for losses amounting to billions of dollars and scores of deaths annually. Virtually all parts of the nation--coastal, moun tainous and rural--are affected by them. Two aspects of the problem of flooding that have long been topics of scientific inquiry are flood frequency and risk analyses. Many new, even improved, tech niques have recently been developed for performing these analyses. Nevertheless, actual experience points out that the frequency of say a 100-year flood, in lieu of being encountered on the average once in one hundred years, may be as little as once in 25 years. It is there fore appropriate to pause and ask where we are, where we are going and where we ought to be going with regard to the technology of flood frequency and risk analyses. One way to address these questions is to provide a forum where people from all quarters of the world can assemble, discuss and share their experience and expertise pertaining to flood frequency and risk analyses. This is what constituted the motivation for organizing the International Symposium on Flood Frequency and Risk Analyses held May 14-17, 1986, at Louisiana State University, Baton Rouge, Louisiana.

Nowadays, major environmental issues are the object of large public debates de- spite the fact that scientific knowledge is often insufficient to draw unequivocal conclusions. Such is the case in the ongoing debate regarding the specific contri- butions of anthropogenic greenhouse gas emissions and of natural climate changes to global warming. At least 10 to 20 years of additional observations will be re- quired, before we will be able to conclude, with certainty, on this subject. In the mean time, and as directed by their immediate interests, people will continue to promote contradictory opinions. The media are, in part, responsible for perpetuat- ing such debates in that they convey indiscriminately the opinion of highly credi- ble scientists as that of dogmatic researchers, the latter, unfortunately too often expressing working hypotheses as established facts. Naturally, in a similarly mis- informed manner, pressure groups tend to support the researcher whose opinions most closely represent either their particular ideological battles or their economic interests and, hence, in their own way, add further to the confusion and obscurity of the debate. Only a few years ago, mercury (Hg)contamination in hydroelectric reservoirs was the object of such media and social biases. At the time, analytical data used to support the discourse were themselves uncertain and numerous hypotheses, often times fanciful, were proposed and hastily "delivered" to the public.

Proceedings of the NATO Advanced Study Institute, Aussois, France, September 4-15, 1985

Antarctica, the sixth continent, was discovered more than 160 years ago. Since then this large, mysterious continent of ice and penguins has attracted world interest. Scientific expeditions from various countries have begun to study the geographical and natural conditions of the icy continent. Systematic and comprehensive inves tigations in the Antarctic started in the middle of our century. In 1956 the First Soviet Antarctic Expedition headed to the coast of Antarctica. Their program included studies of the atmosphere, hydrosphere and cryosphere. Thirty years have since passed. Scientists have unveiled many secrets of Antarctica: significant geophysical processes have been investigated, and a large body of new information on the Antarctic weather, Southern Ocean hydrology and Antarctic glaciers has been obtained. We can now claim that the horizons of polar geo physics, oceanology, and particularly glaciology, have expanded. Scientific inves tigators have obtained new information about all Antarctic regions and thus have created the opportunity to use the Antarctic in the interests of mankind."

In this book major construction projects are reviewed. The aim is to present case studies or topics which would stimulate discussion within the areas of environmental policy, economy, ethics or science. By carefully balancing the needs and interests of all involved stakeholders and by observing basic ethical principles, it is possible to resolve the conflicts and to proceed towards constructive cooperation with commonly accepted environmental objectives. The book further contains the key conclusions and recommendations resulting from the "First International Symposium on Large-Scale Constructions in Coastal Environments" held on the island of Norderney from 21-25 April 1997.

This volume is the result of an initiative of the Commission on the Coastal Environment of the International Geographical Union. The initial concept from which the plan has proceeded was presented at the 24th International Geographical Congress in Japan in 1980. AUTHORSHIP AND COVERAGE All of the articles in this volume have been written by specialists familiar with the coastal segment discussed. Nearly all have been prepared by citizens of the country (and, for that matter, even each subregion) considered. In the case of exceptions (e.g. Suriname), the authors have conducted fieldwork on the coast of the country they treat. In order to preserve the "on-the-spot" integrity of the volume, it was decided not to fill in the blanks along the world's coastline with library researched chapters. Thus, coverage is variable. Nearly every coastal country in Europe is represented whereas for Africa and South America there are major gaps. In addition, there are 2 instances of overlap. In the case of England (with a shoreline of nearly 3,000 km) a complementary chapter on Lincolnshire (with a shoreline of only 155 km) is included. The other case is the general article on the Baltic Coast of the USSR which is supported by chapters on Estonia and Lithuania.

This book provides a state-of-the-art overview of the development of concepts and methodology of hydrological sys tems analysis and its wide range of practical applications. Hydrological systems analysis involves the management, processing and interpretation of huge amounts of geoscien tific as well as ecological and historical data of many different types and sources, which can only be handled coherently and efficiently by using interactive geoscientific information systems. Geoscientific information systems as well as flow simulators are integral parts of the methodology. The methodology is clearly explained in the book and ample figures il lustrate the text. The emphasis of the book is on the practical applicability of hydrological systems analysis in integrated water re source management, nature conservation and environmental planning. The compilation of many case-studies, conducted by TNO geohydrologists and others in recent years, included in the book deals with different temporal and spatial scales and various geohydrological settings in The Netherlands, Poland, the European Union as well as in Indonesia. These case studies underpin the strength and elegance of hydrological systems analysis."

The problem of ice destruction comes most frequently to our attention in engineering glaciology and ice engineering because it is essential in the solution of many problems in the polar regions of the Earth. Ice destruction (like the destruction of any other material, in principle) is a complex problem at the junction of solid-state physics, continuum mechanics, and materials science. Ice, particularly sea ice, is characterized by known anomalies that can be explained by the simultaneous occurrence of solid, liquid and gaseous phases. Even minor temperature fluctuations cause changes in the relationship of these phases and, as a consequence, change the physico-mechanical properties of ice. New hydraulic engineering tasks, associated with the destruction of such a complex material, demand continuous improvement of methods and techniques. The present authors have brought these together in a form which is convenient for a wide range of users. This book covers only local ice destruction, by means other than icebreakers, requiring comparatively low consumption of power in proportion to the volume and mass of destroyed ice. Problems of natural ice destruction under the influence of solar radiation, tidal, wind and wave factors are not dis cussed. Mechanical and thermal methods were the first of many to be used for ice destruction. Their application has involved a greater num ber of techniques, so the first two chapters are the longest."

Proceedings of the NATO Advanced Research Workshop on Advances in Analytical and Numerical Groundwater Flow and Quality Modelling, Lisbon, Portugal, June 2-6, 1987

On May 27-31, 1985, a series of symposia was held at The University of Western Ontario, London, Canada, to celebrate the 70th birthday of Pro fessor V. M. Joshi. These symposia were chosen to reflect Professor Joshi's research interests as well as areas of expertise in statistical science among faculty in the Departments of Statistical and Actuarial Sciences, Economics, Epidemiology and Biostatistics, and Philosophy. From these symposia, the six volumes which comprise the "Joshi Festschrift" have arisen. The 117 articles in this work reflect the broad interests and high quality of research of those who attended our conference. We would like to thank alI of the contributors for their superb cooperation in helping us to complete this project. Our deepest gratitude must go to the three people who have spent so much of their time in the past year typing these volumes: Jackie BeU, Lise Constant, and Sandy Tamowski. This work has been printed from "camera ready" copy produced by our Vax 785 computer and QMS Lasergraphix printers, using the text processing software TEX. At the initiation of this project, we were neophytes in the use of this system. Thank you, J ackie, Lise, and Sandy, for having the persistence and dedication needed to complete this undertaking."

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.

J. J. Beukema, w. J. Wolff & J. J. W. M. Brouns Man is changing the biosphere at an ever increasing Netherlands ministery of Housing, Physical Planning rate. Several of these man-made changes are on a and Health (represented by Dr. G. P. Hekstra), chaired worldwide scale, such as the increase in atmospheric by Dr. w. J. Wolff (Research Institute for Nature concentrations of several gases. In particular the Management) and housed by the Netherlands In ongoing increase of the concentration of at stitute for Sea Research (N. I. O. Z., represented by Dr. mospheric carbon dioxide, by excessive burning of J. J. Beukema). fossil fuels and forest destruction, is well The written versions of the presentations by 23 par documented. By the year 2050, CO levels will ticipants have been brought together in these pro 2 almost certainly be twice the pre-industrial concen ceedings of the Workshop. trations and this is expected to have far-reaching consequences. Direct effects include higher rates of The first paper, by G. P. HEKSTRA, explains how plant production (also in agriculture). Indirect effects trace gases affect UV-B radiation, alkalinity of the might be less favourable: by the intensified sea, rate of photosynthesis, and greenhouse warm 'greenhouse process' (to which several other gases ing."

In the past decades, environmental scientists, economists and physicists have been juggling critical issues within environmental strategies and environmental management styles in order to find a feasible medium between limited resources, long term demands and objectives, and interest groups. In the search for best management alternatives, practice has undergone a pendulum swing between stages that can be characterised as frontier economics, radical environmentalism, resource management/allocation, selective environmentalism and sustainable environmental management. The next stage of management must answer such questions as: Can there be a global - uniform environmental strategy?', or Based on their characteristics, can different issues, different regions and different applications have unique environmental strategies?' Based on this premise, the next stage of management may be identified as risk based sustainable environmental management. The goal of this style will be the risk based, long term, harmonious management of economic resources and environmental preservation for health, safety and prosperity of sustainable populations. When evaluation of risk or risk based ranking of management alternatives enter the picture as part of the overall puzzle, then social policy, ethics and health issues assume a very important role in the management strategy. Economic incentives and environmental constraints have to be considered harmoniously, the main emphasis being placed on protection and preservation of human health and the long term sustaining of populations.

Glaciers or ice sheets are natural accumulations of ice possessing in trinsic motion, which have appeared on the Earth's land surface as a result of the accumulation and transformation of precipitation 2]. Only a very small portion of the surface of the land is now covered by glaciers, and at low latitudes they are found justat high elevations, on mountain slopes. However, glaciers are known to play very important roles in shaping the topography of the Earth, in determiningits past, present, and future climate, and in creating the state of the world Ocean. Recently there has also been a marked increase in the practical value of our knowledge about glaciers, as a part of the human habitat and as a factor affecting the economy. Interest in glaciers on other planets is also growing. Voyages of spacecraft to Jupiter, for instance, have shown that some Jovian satellites possess ice sheets tens of kilometers in thickness."

It is the task of the engineer, as of any other professional person, to do everything that is reasonably possible to analyse the difficulties with which his or her client is confronted, and on this basis to design solutions and implement these in practice. The distributed hydrological model is, correspondingly, the means for doing everything that is reasonably possible - of mobilising as much data and testing it with as much knowledge as is economically feasible - for the purpose of analysing problems and of designing and implementing remedial measures in the case of difficulties arising within the hydrological cycle. Thus the aim of distributed hydrologic modelling is to make the fullest use of cartographic data, of geological data, of satellite data, of stream discharge measurements, of borehole data, of observations of crops and other vegetation, of historical records of floods and droughts, and indeed of everything else that has ever been recorded or remembered, and then to apply to this everything that is known about meteorology, plant physiology, soil physics, hydrogeology, sediment transport and everything else that is relevant within this context. Of course, no matter how much data we have and no matter how much we know, it will never be enough to treat some problems and some situations, but still we can aim in this way to do the best that we possibly can.

Viewed from space, the Earth appears as a globe without a beginning or an end. Encompassing the globe is the atmosphere with its three phases- gaseous, liquid, and solid--moving in directions influenced by sunlight, gravity, and rotation. The chemical compositions of these phases are determined by biogeochemical cycles. Over the past hundred years, the processes governing the rates and reactions in the atmospheric biogeochemical cycles have typically been studied in regions where scientists lived. Hence, as time has gone by, the advances in our knowledge of atmospheric chemical cycles in remote areas have lagged substantially behind those for more populated areas. Not only are the data less abundant, they are also scattered. Therefore, we felt a workshop would be an excellent mechanism to assess the state of-knowledge of the atmospheric cycles of sulfur and nitrogen in remote areas and to make recommendations for future research. Thus, a NATO Advanced Research Workshop ' he Biogeochemical Cycling of Sulfur and Nitrogen in the Remote Atmosphere" was held at the Bermuda Biological Station, St. Georges, Bermuda, from 8-12 October 1984. The workshop was attended by 24 international scientists known for their work in atmospheric cycling in remote areas. This volume contains the back ground papers and the discussions resulting from that workshop. The workshop was organized along the lines of the atmospheric cycle. There were working groups on emission, transport, transformation, and deposi tion."

The idea for this volume came during the dryland sessions of the Association of American Geographers meeting in San Diego in April, 1992. The large number of papers devoted to aeolian processes and landforms indicated to me that aeolian geomorphology had come of age and the last 15 years or so had produced a plethora of papers, books, and edited volumes on all aspects of aeolian geomorphology. Chapter one is my tentative attempt to place develop ments in aeolian geomorphology in a historical perspective and to contemplate some thoughts about the future. The fourteen papers selected address a wide range of issues ranging from micro-scale studies devoted to aeolian dust, sediment transport, and rock varnish in ventifacts to medium-scale studies of dunes and dune forms, reverse desertification, and macro-scale studies of ergs and sand transport pathways. The American Southwest, particularly the spectacular and unique Mojave Desert of California, is featured prominently in seven chapters. I hope this volume provides students and colleagues some new perspectives in aeolian geomorphology as well as pathways for future work."

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.

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.