摘要:

During my last year as coeditor ofWater Resources Research, I undertook a project which culminated in this volume, the first comprehensive special issue in the 22‐year life of the journal. The decision to prepare a special issue of invited papers resulted from discussions with a number of individuals and my assessment that a need existed to provide greater coherence to the study of hydrology. There have been other attempts in the last decade to place specific aspects of hydrology into perspective. One notable effort was by Myron Fiering, who asked colleagues to write on the scientific basis of water resource management [U.S. National Research Council, 1982]. While the papers contained in the current volume do not have as extensive a subject base as those in the earlier work, they do address many important topics in hydrology. The 19 authors who have contributed to the 15 papers in this volume have, collectively, over 500 years of professional experienc

ISSN:0043-1397    

DOI:10.1029/WR022i09Sp0001S

年代:1986

数据来源: WILEY

摘要:

Emerging problems of environmental change and of long range hydrologic forecasting demand knowledge of the hydrologic cycle at global rather than catchment scale. Changes in atmosphere and/or landscape characteristics modify the earth's metabolism through changes in its biogeochemical cycles. The most basic of these is the water cycle which directly affects the global circulation of both atmosphere and ocean and hence is instrumental in shaping weather and climate. Defining the spatial extent of the environmental impact of a local land surface change, or identifying, for forecasting purposes, the location and nature of climatic anomalies that may be causally linked to local hydrologic persistencies requires global scale dynamic modeling of the coupled ocean‐atmosphere‐land surface. Development, evaluation, verification, and use of these models requires the active participation of hydrologists along with a wide range of other earth scientists. The current state of these models with respect to hydrology, their weaknesses, data needs, and potential utility are discus

ISSN:0043-1397    

DOI:10.1029/WR022i09Sp0006S

年代:1986

数据来源: WILEY

摘要:

The role of scale in the rainfall characterizations resulting from different rainfall models is the main issue under study. Three different types of models are analyzed: temporal rainfall models at a point, areal storm rainfall models, and space‐time rainfall representations. The perspective is taken that precipitation models need mainly to incorporate those features of the process which lead to an adequate representation under some amount of local averaging either in time or in space or in space and time. Thus the characteristics of the averaged rainfall process resulting from the different models are analyzed with a special emphasis on the role of the scale of fluctuation of the process in these characteristic

ISSN:0043-1397    

DOI:10.1029/WR022i09Sp0015S

年代:1986

数据来源: WILEY

摘要:

Evaporation is an important component of the hydrological cycle; for example, over land surfaces it amounts on average to about 60% of precipitation. This means that for hydrological purposes such as water budget calculations, the prediction or forecasting of floods and droughts, and for dynamic weather forecasting and climate modeling, it is indispensable to have reliable information on land surface evaporation. In mapping a strategy for this, decisions must be made regarding the scales at which this phenomenon is best parameterized. The atmosphere has the capacity of integrating and smoothing the effects of small‐scale irregularities over larger areas. Therefore a more thorough understanding of turbulent transport mechanisms in the atmospheric boundary layer should lead to improved parameterization methods of evaporation at the regional and watershed scal

ISSN:0043-1397    

DOI:10.1029/WR022i09Sp0039S

年代:1986

数据来源: WILEY

摘要:

The search for regularities in hydrologic relationships is discussed against the background of the general types of predictive models used in science. The various approaches to the study of water are compared and contrasted. The ideas discussed are illustrated by examples from the development of techniques in flood hydrology and by personal conclusions on the sources for new hypotheses in flood hydrology and the possibility of their verification.

ISSN:0043-1397    

DOI:10.1029/WR022i09Sp0046S

年代:1986

数据来源: WILEY

摘要:

Snow cover crystals must be classified in a physically meaningful way. Previous classification systems are not sufficiently detailed or not based on sufficient knowledge of the physical processes. A new system is proposed based on our current knowledge of the physical processes of metamorphism. As more information about snow metamorphism is developed, the labels attached to snow grains should evolve too. Two levels of classification are proposed here. For practical purposes only a few terms like rounded and faceted are necessary, but for a more complete description a more detailed system is also given. The most basic description given in the table could be useful to many practitioners, while the more complete description given in the appendix will be necessary for many purposes.

ISSN:0043-1397    

DOI:10.1029/WR022i09Sp0059S

年代:1986

数据来源: WILEY

摘要:

The present state‐of‐the‐art of modeling of flow of water and transport of sediment in alluvial channels is assessed. The characteristics of several presently available models are described, along with their similarities and differences. The general problems in present models are found to be in their choice of sediment transport function, assessment of resistance to flow and how it varies with changes in flow and cross section, modeling of bed armoring and its effect on sediment transport, the allocation of net scour and fill in a stream cross section, and the handling of upstream and downstream boundary conditions. Current work in these areas is described. The need for the inclusion of bank scour, stream migration, and meander development is discussed, along with present methods for approaching the assessment of their effects. Needed areas of research are outlined for the improvement of prediction of scour and fill in alluvial cha

ISSN:0043-1397    

DOI:10.1029/WR022i09Sp0071S

年代:1986

数据来源: WILEY

摘要:

Some aspects of the underlying conceptualizations (as opposed to experimental methodologies or mathematical algorithms) in soil water physics are reviewed. Contemporary issues relating to the symmetry properties of the Richards Equation, the status of the energy picture of soil water, and the theoretical description of coupled heat and water flows in soil are raised to exemplify as yet unresolved problems in the “physics” of soil water physics. Four basic questions which formalize these problems are posed as suggestions for future resea

ISSN:0043-1397    

DOI:10.1029/WR022i09Sp0083S

年代:1986

数据来源: WILEY

摘要:

This paper gives a review of our current conceptual understanding of the basic processes of water flow and chemical transport in the untsaturated (vadose) zone and of various deterministic mathematical models that are being used to describe these processes. During the past few decades, tremendous effort has been directed toward unravelling the complexities of various interactive physical, chemical, and microbiological mechanisms affecting unsaturated flow and transport, with contributions being made by soil scientists, geochemists, hydrologists, soil microbiologists, and others. Unfortunately, segmented, disciplinary research has contributed to a lack of experimental and theoretical understanding of the vadose zone, which, in turn, has precluded the accurate prediction and management of flow and contaminant transport through it. Thus a more unified and interdisciplinary approach is needed that considers the most pertinent physical, chemical, and biological processes operative in the unsaturated zone. Challenges for both fundamental and applied researchers to reveal the intricacies of the zone and to integrate these with currently known concepts are numerous, as is the urgency for progress inasmuch as our soil and ground water resources are increasingly subjected to the dangers of long‐term pollution. Specific research areas in need of future investigation are outline

ISSN:0043-1397    

DOI:10.1029/WR022i09Sp0089S

年代:1986

数据来源: WILEY

摘要:

The movement of nonaqueous phase organic liquids (NAPL) in a groundwater system involves both miscible and immiscible flow phenomena. A broad overview of the task of modeling these flows is presented along with a discussion of various problematic issues related to such a modeling effort. Descriptive equations are obtained through combination of the species balance equations for multiphase fluid flow in a porous medium and appropriate constitutive relationships. Tabulation and discussion of these constitutive relations yields insight into model requirements. Under certain assumptions, the modeling problem can be reduced to the solution of two nonlinear partial differential equations in two unknowns. An example simulation of the movement of NAPL emanating from two point sources in a confined aquifer is presented to illustrate present modeling capabilities.

ISSN:0043-1397    

DOI:10.1029/WR022i09Sp0109S

年代:1986

数据来源: WILEY