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Designing Water Infrastructure for Climate Uncertainty

April 30, 2019 |

Media Club [CC BY-SA 2.0 (]

This article was originally published on 

“In Kenya’s second largest city, Mombasa, the demand for water is expected to double by 2035 to an estimated 300,000 cubic meters per day. In Mombasa’s current warm and humid climate, that water comes from a substantial volume of precipitation that may also change significantly as the region warms in the coming decades in line with global climate model projections.

What’s not clear from the projections, however, is whether precipitation levels will rise or fall along with that warming.

The ultimate direction and magnitude of precipitation change is a major concern for designers of a proposed dam and reservoir system that will capture runoff into the Mwache River, which currently totals about 310,000 cubic meters per day. The substantial uncertainty in future runoff makes it difficult to determine the reservoir capacity necessary to meet Mombasa’s water demand throughout its estimated 100-year lifetime. City planner are therefore faced with deciding whether to invest in an expensive, large-scale dam to provide a consistent water supply under the driest future  projected by the models, a smaller-scale dam that could accommodate current needs, or start small and build capacity as needed.

To help cities like Mombasa sort through such consequential decisions, a team of researchers at the MIT Joint Program on the Science and Policy of Global Change has developed a new, systematic approach to designing long-term water infrastructure amid climate change uncertainty. Their planning framework assesses the potential to learn about regional climate change over time as new observations become available, and thus evaluate the suitability of flexible approaches that add water storage capacity incrementally if the climate becomes warmer and drier. The researchers describe the framework and its application to Mombasa in the journal Nature Communications…”

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