Hydrologic Sciences Taking Stock and Looking Ahead (1998) / Chapter Skim
Currently Skimming:
1 Wolman Lecture: Hydrologic Science...in Landscapes...on a Planet...in the Future
1 Wolman Lecture: Hydrologic Science...in Landscapes...on a Planet...in the Future
Pages 10-43
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 10... ...
proposed that there exists, or ought to exist, a distinct geoscience referred to as hydrologic science. Hydrologic science would be analogous to atmospheric science, geologic science, or ocean science but different from traditional hydrology, which the committee equated with engineering or applied hydrology.
|
From page 11... ...
The report held out the promise of solutions to specific problems such as "the possible redistribution of water resources due to climate change, the ecological consequences of large-scale water transfers, widespread mining of fossil ground water, the effect of land use changes on the regional hydrologic cycle, the effect of nonpoint sources of pollution on the quality of surface and ground water at a regional scale, and the possibility of
|
From page 12... ...
Klemes (1988) has also been adamant that scientific research in hydrology be kept distinct from the technological activity of using hydrology to manage water resources.
|
From page 13... ...
has even stated that spatially distributed, physically based hydrologic modeling is ripe for some kind of intellectual crisis and revolution that would redefine its scope and realistic possibilities. Similar comments on the misleading aspects of probability analyses, largely resulting from incorrect understanding on the part of users, have been made by Klemes (1982, 1989)
|
From page 14... ...
We should concern ourselves with phenomena that are of some interest to society, even if society must be continually informed about the significance of our research targets. The challenge at present lies in defining ways in which hydrologic scientists might gain support for their activities through functioning as engaged members of society.
|
From page 15... ...
Understanding the state and functioning of water at any of these scales and the relationships between the various scales can be a useful contribution to society, if findings are translated into a form that is accessible to other members of that society. Engineering hydrology was not developed to analyze large-scale processes with multiple feedbacks between various loops in the water cycle.
|
From page 16... ...
We live on a planet, and that fact has hydrologic significance ranging from the mechanisms by which the energy and water balances of the entire Earth are stabilized in a range that is hospitable for humans and other biota to investment decisions that must be made by local water authorities about their future water supplies. Furthermore, we now realize that human activities can influence
|
From page 17... ...
· We live in landscapes, the topography of which is a dominant influence on spatial and temporal patterns of water storage and surface and subsurface transport of water and its constituents. We also recognize that humans can influence the hydrologic cycle on the scale of even the continental-scale river basins.
|
From page 18... ...
There is much new science to be done in investigating these patterns and in discovering new aspects of the behavior of water and the materials it carries, rather than focusing most of the discipline's attention on improving computational methods and on calibration of simulation models. Learning how to represent these patterns of materials and processes offers the prospect of improving their model formulation in ways that will truly enhance our understanding of the hydrologic cycle.
|
From page 19... ...
In addition, the results of global and regional models of change (atmospheric general circulation models [GCMsi, demographic projections, land use scenarios) need to be translated into predictions of ground-level conditions and processes such as soilmoisture regimes, ground water recharge, runoff volumes, floods, droughts, lake levels, and soil erosion patterns.
|
From page 20... ...
(1995) among others have drawn together the current level of field experience into a convincing theory of how hillslope and channel network characteristics govern basin hydrologic response, including the distribution of soil moisture at a range of geographical scales.
|
From page 21... ...
. Public policy at all levels of social organization now requires hydrologists to interact with atmospheric scientists, biogeochemists, and others to gradually reduce uncertainty about the terrestrial and atmospheric processes at planetary and regional scales that may be affected by natural and anthropogenic environmental change.
|
From page 22... ...
At the surface, landscapes consist of complex hillslopes converging on channel networks that in map view have a beelike hierarchical structure. Topography creates preferred pathways for overland and shallow subsurface water (Kirkby and Chorley, 1967; Dunne et al., 1975; Beven and Kirkby, 1979)
|
From page 23... ...
(1998a, b) have modeled the formation of channel networks and drainage basins as the result of hydrologically driven sediment transport.
|
From page 24... ...
This is necessary if, in the face of such uncertainty, we are ever going to be able to provide scientific advice on how to make environmental management decisions about, for example, whether extensive timber management has long-term consequences for flood levels (Jones and Grant, 1996~. Given the importance of regional-scale river basins and their valley floors as loci of settlement, agriculture, commerce, and ecological values, it is surprising
|
From page 25... ...
In recent decades there has been little quantitative study of floods as processes or of how the process of flood generation is influenced by large-scale environmental controls, especially in large basins. Although attention is now being paid to the mesoscale atmospheric circulation processes that govern rainfall character, there is no comparable ground-level investigation of the floodgenerating role of season-long soil moisture patterns, regional-scale patterns of soil waterholding properties and topography, the hydrographic structure and disparate geography of major tributary basins, valley floor geometry, regional land use change, land drainage, or diking over 1,000-km scales, as occurs along the Mississippi River and is proposed in the Bangladesh Flood Action Plan.
|
From page 26... ...
So is the impact of regional drought on the outcropping and discharge of ground water in a stream network or the down-valley advection and diffusion of a sediment wave released from hillslopes by agricultural colonization. Second, though it may be difficult, improving the analysis of large complex problems is
|
From page 27... ...
Atmospheric scientists have pointed the way by studying how the energy and water balances of extensive continental surfaces affect atmospheric dynamics at regional and larger scales. That information is needed for reducing uncertainty in global circulation models, but once the activity grew it became apparent that it could also lead to improvements in local meteorology and hydrology.
|
From page 28... ...
During the past decade, the output of all hydrologic journals has increased dramatically, and in the main research journals, such as Water Resources Research, Journal of Hydrology, Journal of Geophysical Research, Reviews of Geophysics, and Hydrologic Processes, many papers have appeared that would be classified as scientific hydrology by even the harshest critics of past practices. That conclusion can be extended to those journals to which hydrologists have contributed more recently, such as the Journal of Climate or Earth Surface Processes and Landforms.
|
From page 29... ...
Thus, we become identified as a particular kind of hydrologic scientist: geomorphologist, soil physicist, ground water hydrologist, surface water hydrologist, etc. We attend different sessions at scientific meetings, and spend little of our time contemplating the connections between weather, surface water, soil hydrology, and ground water that for example, at the scale of a large river basin might hold keys to the generation of floods.
|
From page 30... ...
Hydrologic scientists will continue to come from a broad range of backgrounds. Even if new graduate programs are developed in hydrologic sciencewhich is an excellent idea that some universities can afford most people entering the field will be trained and employed outside such programs for the foreseeable future.
|
From page 31... ...
Development or recapitulation of theory would be an important tool in agenda building for hydrologic science. The theoretical physics model referred to above suggests that it would increase and intensify collaborations and lead to proposals possessing a wide degree of reviewer support.
|
From page 32... ...
First, the need for hydrologic scientists to stay sensitive to major socioenvironmental questions requires that we take seriously the task of tracking and responding to the "web" of information, proposed earlier as a model for a hydrologic scientist's career. There is no substitute for broad and continuing education and flexibility of interest in nature and society.
|
From page 33... ...
It is difficult to expect students with no exposure to basic climatology, physical geography, or ecology to generate the idea of studying, say, the processes that lead to rainfall distributions over topography and their role in flood generation or how climatic changes might gradually affect plant community characteristics and hence the water balance. Thus, we also need to create some time in the education of these scientists to learn about the physics, chemistry, and biology of waters near the Earth's surface.
|
From page 34... ...
Exceptions to this generalization are the skillful measurements of small-scale subsurface water storage and flow processes in some field and laboratory experiments and monitoring studies. Yet there have recently been some technological revolutions affecting the availability, or in some cases the promise, of more and better data than have been available before.
|
From page 35... ...
, radar measurements of snow water equivalent (Shi and Dozier, 1996) , highprecision topography for low-lying areas such as valley floors, and even surface soil moisture for some restricted range of environments.
|
From page 36... ...
However, among hydrologic scientists, only hydrometeorologists seem in a position to make such requests, because of the previously mentioned lack of theoretical convergence and agenda building among hydrologists. The chance to guide hydrologic data collection could be an important product of agenda building.
|
From page 37... ...
In its oversight of the science the committee could take some responsibility for maximizing the nation's entire investment in hydrologic research by promoting interactions between academe and the federal agencies interested in water. This interaction has declined precipitously during the past 10 to 15 years as federal budgets have tightened.
|
From page 38... ...
We have to extend our ability to use or at least to understand a wide variety of new technologies that for the first time offer to measure the spatial characteristics of hydrologic processes and characteristics at scales up to regional and global. Finally, the oversight mentioned above needs to be provided by the NRC, which would not only act as an authoritative voice on scientific hydrology but also generate a stream of creative advice about continuing opportunities in hydrologic science.
|
From page 39... ...
1998b. Stochastic forcing of sediment transport in channel networks.
|
From page 40... ...
1992. Physically based hydrologic modeling.
|
From page 41... ...
Pp. 255-280 in The Geology of North America, O-1: Surface Water Hydrology.
|
From page 42... ...
1995. On the relative roles of hillslope processes, channel routing, and network geomorphology in the hydrologic response of natural catchments.
|
From page 43... ...
1963. A theoretical analysis of ground water flow in small drainage basins.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.