Avoiding Future Disruption of Services
this will be obvious: land-locked countries need not consider sea-level rise, nor need low-elevation, low-latitude areas be concerned with changes in freeze/thaw cycles. But because the key variables are not always this obvious, there should be an initial general understanding about which variables need to be examined in detailed quantitative terms.20 Given the limits on the information available, a risk assessment approach should be both qualitative and quantitative to minimize the costs of engineeringbased adaptation strategies and loss (box 2.10). Besides raw climate information, sound strategy should map critical infrastructure links—kilometers of railroad tracks or roads, percentage of roads paved or gravel-surfaced, number of bridges or length of subway lines—as well as the physical and institutional context. (This has begun for Ethiopia.21) What is the landscape surrounding the asset? Who has jurisdiction over operations, maintenance, and design—both the original design and future retrofits? Are drainage systems integral? Are they managed by the roads authority or by the urban water and sanitation authority? What standards and manuals provide technical specifications? What is the intended design life? Has it already been, or is it likely to be, exceeded? What climate-related problems have already arisen? What non- climate-related problems? Knowing the internal state of a structure is also important. Innovative technologies, such as nano-sensors, can monitor how during extreme events infrastructure reacts to water levels and currents, wave action, winds, and excessive temperatures.
Box 2.10 A Five-Step Risk-Assessment Approach to Infrastructure Design 1. Focus on infrastructure that has a long life (more than 40–50 years); infrastructure designed for a shorter life already has flexibility incorporated into the facility replacement schedule. 2. Identify geographic areas that are particularly sensitive to climate change, such as coastal or low-lying areas. 3. Assign a likely probability of environmental change to these sensitive areas to determine if such changes are likely over the useful life of the facility. 4. Create several designs based on different standards to account as needed for a changing environment. For each design estimate the cost, both replacement and economic, of any disruption. 5. Apply the hazard probability to design components that will be affected by a changing environment. Estimate the likely costs of each in current dollars. Choose the design with the lowest net value cost. The third step is particularly critical. The accuracy of the predicted probability of e nvironmental change will depend on the reliability of the climate projections. Hence, planners must interpret results with caution, using corridors of values rather than single optimal values. Source: Adapted from Meyer 2007.
Turning the Right Corner • http://dx.doi.org/10.1596/978-0-8213-9835-7
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