Overview

Figure 1. Decision Analytic Process used to helped
water agencies consider climate change

As water planners and managers become increasingly aware of global climate change and its possible impacts on water resources, they are seeking climate change information pertinent to their planning needs. To address these needs, RAL scientists, supported by the Water Research Foundation and NCAR's Assessment Program have developed climate change educational materials for the water resources community. Despite the pressing need, many water utility managers remain unsure if or how they should adapt to climate change. They correctly note that many uncertainties remain. In particular, reliable projections of local–scale changes in precipitation are not yet possible.

Figure 2. Process diagram for Palm Beach Count Water
Decision Support Process

This uncertainty arises partly from fact that precipitation is inherently much more variable over time and space than is temperature. It also arises from the inability of coarse–resolution climate models to adequately simulate the fine–scale processes that determine where and when precipitation occurs. Statistical and dynamical downscaling techniques and higher–resolution climate models, made possible by more powerful computers, can help to increase the reliability of regional climate projections, but they won't eliminate all sources of uncertainty. In short, we know that climate change is likely to affect water resource availability and quality but we also know that we have a limited ability to foresee the full details of those changes, especially at local scales relevant to water planning.

Figure 3. A screen–shot showing the Upper Colorado,
Platte, and Arkansas Basins within the Water Evaluation
and Planning (WEA) decision support model

Uncertainty is not a new phenomenon for water planners. Substantial uncertainties have long surrounded projections of future population growth, changes in water use habits, and construction costs. Uncertainty surrounding future climate projections is not fundamentally different from these more familiar uncertainties, except in degree and in the length of the time horizon. Effective planning can proceed, despite such uncertainties, by adopting a risk–management approach that considers a range of plausible projections for the most relevant, but uncertain variables.

Figure 4. Simplified Water–Energy Nexus

Over the past few years, we have engaged with a select set of municipal water providers and related regional coordinating bodies in the development of a decision support process to facilitate assessments of water utility vulnerabilities and response options to prospective climate changes. These projects focused, in particular, on the problem of planning in the context of uncertainties surrounding the local–scale hydrologic changes that will result from global climate change. This has resulted in several reports, including Climate Change in Water Utility Planning: Decision Analytic Approaches. The projects have developed and demonstrated a structured assessment process to help the drinking water industry conduct scientifically sound and cost–effective assessments of utility vulnerabilities and adaptation options in the context of climate variability and change.

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Primary Contacts

• RASMUSSEN, Roy: | HAP DIRECTOR | ph: 8430 | email: rasmus

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Lara Ziady, Web developer
ziady@ucar.edu
+1-303-497-8442

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