Better Analysis of Uncertainty Needed for Water Resource Projects

When the Corps of Engineers estimates costs and benefits of proposed water resource projects, it encounters uncertainty. The two basic probability approaches to analyzing uncertainty are the "relative frequency" approach which relies on past events and the "subjective interpretation" approach which depends on whether an event will occur at all.

The Corps is more successful in analyses of costs and benefits which depend on the "relative frequency" approach. For example, if floods have occurred at a certain frequency in the past, they can be expected to occur at similar frequencies in the future. However, predictions of events such as future development in a flood-prone area are subjective. The Corps' treatment of this type of uncertainty could be improved. For example, when an estimate of future events is based on the judgment of a panel of experts, it should reflect the degree of agreement in the panel, not just the "average" opinion.

Recommendations

Our recommendations from this work are listed below with a Contact for more information. Status will change from "In process" to "Open," "Closed - implemented," or "Closed - not implemented" based on our follow up work.

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