Reservoir Sustainability and Sediment Management

AbstractDespite mounting demand for a more sustainable worldwide water supply system, available reservoir capacity is relentlessly diminishing due to sedimentation. Neither sustainable reservoir life spans nor intergenerational equity is achieved through conventional cost-benefit analyses (CBAs), which render all benefits and costs projected to occur more than several decades into a project as negligible. Consequently, future costs, including dam decommissioning or retrofitting with sediment management facilities, would be regarded as nonfactors in an analysis. CBAs have also historically failed to account for infrastructure and environmental impacts of sedimentation over time. Alternatives to the traditional application of the CBA do exist, however, such as dam owners instituting retirement funds or insurance policies, beneficiaries paying for rehabilitation or maintenance, and economists incorporating infrastructure damages and potentially logistic discount rates into their analyses. A brief case study of Gavins Point Dam shows that available information on damages due to a lack of sediment management account for 70% of the actual construction cost and would likely exceed construction costs if all damage information were available. By integrating these alternatives, economic analyses for reservoirs will be more accurate, reservoir life spans will be more sustainable, profits will be extended indefinitely, and the economic burdens placed on future generations will be lessened.