Designing water infrastructure for climate uncertainty
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...