Economic Analysis of Structural Flood Proofing

An economic analysis of flood proofing was applied to a case study of residences and commercial establishments in the Boulder Creek flood plain of Boulder, Colo. Two alternate plans (one involving nine items and the other four items of flood proofing) were analyzed in terms of their costs of installation and the benefits derived from reduced flood damages. Data on levels of inundation for floods up to the 100-yr flood were obtained for each structure in the flood plain from field surveys. Costs of flood proofing were estimated from standard construction cost references. Damages were based on standardized flood depth-damage relationships for the structure and its contents. The results indicate that, in general, flood proofing all structures in a flood plain, such as Boulder Creek, is not economically justified, but that on an individual structure basis some residences and many commercial establishments can be flood proofed at costs less than the benefits derived.