ISSN:0262-6667    

DOI:10.1080/02626668309491139

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

On the occasion of the 60th anniversary of the International Association of Hydrological Sciences, the 100th and 50th anniversaries of the First and Second International Polar Years, and the 25th anniversary of the International Geophysical Year, it seems appropriate to re-examine the world's water balance and the role of snow and ice in the global hydrological climatic system. Snow cover on land (especially in the Northern Hemisphere) and sea ice (especially in the Southern Hemisphere) vary seasonally, and this seasonal change has an important effect on the world climate because snow and sea ice reflect solar radiation efficiently and affect other heat flow processes between atmosphere and land or ocean. Glaciers, including ice sheets, store most of the fresh water on Earth, but change dimensions relatively slowly. There is no clear evidence that the glacier ice volume currently is declining, but more needs to be known about mountain glacier and ice sheet mass balances. The current rise in sea level poses an enigma: thermal expansion of the oceans may account for half of the present rise, but the other half is unexplained. Although major changes in the large ice sheets take place over time scales of 104to 105years, marine ice sheets may be subject to rapid disintegration due to grounding line instability, perhaps accompanied by surging. Ice cores may produce remarkably complete histories of air temperature, precipitation, fallout, and atmospheric composition. A recent core through the Greenland Ice Sheet shows an abrupt transition from glacial to modern climate just over 10000 years ago, suggesting that climate is an “almost intransitive” system. Because of the possibility of abrupt climate transitions and the uncertain stability of the West Antarctic Ice Sheet, future climatic variations are difficult to predict. The calculated heating of the atmosphere in the polar regions due to CO2increase is, therefore, of special interest.

ISSN:0262-6667    

DOI:10.1080/02626668309491140

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

A number of questions relative to the background of hydrology are discussed. What does the term “water” mean in a scientific context? Why is there water on our planet? Why is most of it in liquid form? What does science tell us about the molecular structure of liquid water? Can liquid water be treated as a continuum? Is water a Newtonian fluid? What is the scientific basis for the equations of water movement commonly used in hydrology? Can the various approaches to the study of water movement be reconciled with one another? What does the concept of water mean to the physical scientist, the biological scientist, the social scientist and above all to the hydrologist?

ISSN:0262-6667    

DOI:10.1080/02626668309491141

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

ISSN:0262-6667    

DOI:10.1080/02626668309491142

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Rapid economic development and population growth exert great pressure on hydrological, erosion/sedimentation and biogeochemical cycles. The cycles are closely related, with the hydrological cycle having the leading role. In the first instance only water aspects of the impact of human activity are discussed: namely, the roles of water withdrawals, reservoirs and transfers as compared with the natural components of the water balance; impacts of irrigation and agriculture in general; the problem of closed lakes; water management problems stemming from the current water resources situation. This is followed by a discussion on impacts of human activity on water and erosion/sedimentation with particular emphasis on consequences of agriculture. Then there is a discussion on impacts of economic activity on water and hydrochemistry: changes of chemical transport by rivers; perturbations of the nitrogen and phosphorus cycles. Mankind faces the need for an active control of water resources and hydrologic regime on a large scale. The control inevitably requires an interdisciplinary approach based on understanding the wide scope of hydrological processes. For hydrology there is no other way but to accommodate itself to this interdisciplinary setting.

ISSN:0262-6667    

DOI:10.1080/02626668309491143

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The purpose of this paper is three-fold. First, multiobjective decision making is viewed as a philosophy and a process, rather than merely a set of procedures and algorithms; while methodologies are obviously important, the framework within which they are applied, and the communication between analysts and decision makers are the crucial determinants of the success in their application. The second part of the paper is devoted to a brief outline of some methodologies which have been found useful in multiobjective planning and management of water resources systems. Finally, the main thrust of the paper lies in presentation of experience gained in several studies.

ISSN:0262-6667    

DOI:10.1080/02626668309491144

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Monitoring data can rarely be generalized unless one knows the significant connections and interactions between the parts of an ecological system. Similarly it is usually not possible to assess the ecological effects from bioassays or toxicity tests with individual organisms. In view of the great number of existing chemicals and considering the large amount of environmental pollutants created every day by civilization we need to develop and apply general concepts (physical chemical substance specific data, unit processes) on the behaviour, distribution and fate of pollutants in order to assess their environmental behaviour and their potential effects on ecological systems and on human health.

ISSN:0262-6667    

DOI:10.1080/02626668309491145

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Operational hydrology requires reliable and accurate instruments and methods of observation. It is useful to review developments, particularly those of the last decade. Two milestones of this development may be mentioned, both actively supported by the IAHS International Commission on Surface Water, namely the IAHS/UNESCO/WMO (1970) Symposium in Koblenz, and the WMO Seminar in Padova 1975 (WMO, 1975). In assessing the trends, the interconnections of hydrometry with network design and data processing are discussed. Suggestions are also submitted for further developments including research and the potential applications in one particular field, where new instruments and methods are badly needed, specifically the measurement of three-dimensional turbulent flow in streams and lakes. Problems and results are introduced in connection with three-dimensional flow measurement to give an example for the trend of development.

ISSN:0262-6667    

DOI:10.1080/02626668309491146

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The groundwater balance for the city of Nagaoka, Japan is presented as a case study. At Nakaoka there are three interesting features: (a) in winter groundwater is ejected from pipes under the roads to melt freshly fallen snow, (b) the river is hydraulically in contact with the aquifers, (c) the water table has remained quasi-stationary for the last five years despite the vast pumping programme. The main sources of recharge are: the River Shinano, deep percolation from irrigated fields, snowmelt in spring, and rainfall throughout the year. The water table was monitored using observation data from about 200 wells; during the irrigation period in August there was an inflow of groundwater, but groundwater resources were depleted in winter and spring by pumping for the snow-melting scheme. The evaluation and estimation of the components of the groundwater balance are discussed; in particular methods of measuring deep percolation either directly or indirectly are examined.

ISSN:0262-6667    

DOI:10.1080/02626668309491147

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The polar ice sheets of Greenland and Antarctica are unique sedimentary environments which offer valuable information on the climate and atmospheric environment of the past. The prevailing low temperatures, lack of mixing of strata, and relatively high accumulation rates result in high quality records which may be resolved in great detail, frequently at the scale of seasons of the year. Deformation of ice at great depth reduces the resolution but extends the available time span to hundreds of thousands of years. Climatic and environmental information is obtained from ice cores penetrating the ice sheets and is derived from the composition of the ice itself, as well as from chemical impurities and entrapped air bubbles. Ice core signals can be related to climatic variables such as mean annual temperature, summer warmth, and past precipitation rates; past environmental effects that can be detected from ice core data include volcanic eruptions, changes in solar activity, and the impact of man's activities on recent snow composition.

ISSN:0262-6667    

DOI:10.1080/02626668309491148

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor