Sustaining Our Water Resources (1993) / Chapter Skim
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Changing Concepts of System Management
Changing Concepts of System Management
Pages 78-91
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From page 78... ...
Over the past decade committees of the Water Science and Technology Board (WSTB) have reached similar conclusions concerning water resource management.
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From page 79... ...
In this paper I focus on two ecological concepts, discuss some recent developments in ecological thought relating to those concepts, consider the management implications of these developments, and end with a discussion of future challenges for ecology. ~ O CHANGING ECOLOGICAL CONCEPTS: NATURE IN BALANCE The first concept is one that is as much philosophical as ecological -- nthe balance of nature." Over the past 50 years, ecologists have gradually come to recognize that nature is not always in balance.
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From page 80... ...
Long before humans began building dams, beavers were major agents for channel modification throughout much of North America. The activities of beavers greatly alter stream ecosystem function, increasing retentiveness, increasing anaerobic processes, and lengthening the turnover time of material in the streams (Neiman et al., 1988~.
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From page 81... ...
Each of these ~patches" has characteristic biotic communities with associated rates of organic matter processing, and each operates on a somewhat different time scale. For example, insects of the shifting sandy sediments have very short generation times, whereas many species on the more stable woody debris have only one generation per year.
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From page 82... ...
.__ . ——— Sustaining Our Water Resources August o o · O · O · O o o o o zooplankton are abundant, algal biomass is lower with proportionally fewer small individuals, water clarity is greater, heat content is higher, and mixing depth is greater.
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From page 83... ...
For example, when disturbances caused by variable water discharge, high summer temperatures, and massive sediment transport are removed, the system changes. This has happened below Glen Canyon Dam, and it is one of the issues addressed by the WSTB's Glen Canyon Environmental Studies (GCES)
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From page 84... ...
. This includes incorporating environmental dimensions into decisions on dam operation, operating the dam in an experimental mode in which different release schedules are followed to assess their effect on downstream ecosystems as well as on power generation, and ongoing scientific assessment of the downstream ecosystem to provide continued guidance to dam operators.
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From page 85... ...
I offer the following partial list of desired future conditions that are guiding watershed management as an example of how this new perspective could alter management of lands that in decades past have been managed primarily to meet a specified timber yield: · populations of native fish species that equal or exceed current levels, · maintenance of a diversity of stream productivity levels to maintain diverse gene pools of aquatic species, and
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From page 86... ...
In past decades, riparian management objectives in the West have focused on controlling stream temperatures and limiting sediment input to meet water quality goals while still harvesting timber. Ecological research has shown that the riparian zone provides habitat and food resources for fish and other wildlife, provides channel structures (most important, woody debris)
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From page 87... ...
Studies currently being contemplated by the WSTB on the science of inland aquatic ecosystems could provide further guidance in this area. Current problems in water resource management offer numerous challenges to the ecologist.
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From page 88... ...
A final research challenge for ecologists is provided by the need to restore aquatic ecosystems, so well documented by the recent WSTB report Restoration of Aquatic Ecosystems (NRC, 1992~. As human assaults on natural systems have accelerated over the past decade, so has the need for a more holistic concept of system management that has the goal of maintaining and restoring the ecological integrity of the resource rather than simply preserving water quantity or quality.
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From page 89... ...
National Review Council, Committee to Review the Glen Canyon Environmental Studies. National Academy Press, Washington,D.C.
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From page 90... ...
Pp.124-177 in Colorado River Ecology and Dam Management. National Research Council, Committee to Review the Glen Canyon Environmental Studies.
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From page 91... ...
Pp. 75-101 in Colorado River Ecology and Dam Management.
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