7997

• UCREFRP Catalog Number: 7997
• Author: Nash, L. L. and P. H. Gleick.
• Title: The Colorado River Basin and Climatic Change, The Sensitivity of Streamflow and Water Supply to Variations in Temperature and Precipitation.
• USFW Year: 1993.
• USFW - Doc Type: EPA 230-R-93-009,
• Copyright Material: NO

Beyond the scope of this study were several important issues that policymakers and water-supply
managers will have to consider. First, the environmental and ecological impacts of changes in water supply
have not been addressed here. In general ecosystems are more sensitive to seasonal, monthly, daily, and
even hourly changes in streamflow and water quality than to long-term changes. Unlike water supply, the
impacts on the environment cannot be adequately assessed using aggregated time periods or large-scale
models. Undoubtedly, however, given the predicted rate of climatic change and the potential magnitude of
runoff changes examined here, serious ecological problems would occur.

This study has also not taken projected future economic developments nor some future demands
into account. Currently the issue of reserved water rights and Native American claims have obscured future
demand scenarios in the basin. Because of the large amounts of water involved, these unresolved claims
could have dramatic impacts on water allocation throughout the region and thus add to the uncertainty that
the basin faces.
Finally, while this study has suggested what the impacts of climate change could be on water
supply, it has not addressed the impacts of climate change on water demand. In fact, demands will change
both in time and space. Obviously, agricultural water demand will vary as crops and production patterns
are altered in response to climatic changes. Ecosystem water requirements will also vary, both In response
to increased temperature and as a result of ecological and environmental changes. Urban and industrial
usage will change as a result of both changes in climate and changes in population. It is quite possible
that changes in demand over the next 50 to 100 years will equal or exceed changes in supply. In all
likelihood, the greatest possibilities for adapting to climatic change lie in the area of demand management,
particularly in the agricultural and urban sectors, and the potential for conservation and water transfers needs
to be assessed from both a quantitative and an institutional perspective. If we are to plan adaptation
strategies. future research must address the integrated impacts of climatic change on demand and supply
across sectors.

Given the prospect of future climatic changes, it is imperative that we consider how we can increase
the resiliency of our existing water-management systems and minimize the social and environmental impacts
of changes in water availability. We need to identify those responses that will provide us with the greatest
flexibility in the coming decades and to develop management schemes that recognize both the variability
and the dynamic nature of our climate.

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