This technical note describes how David Ford Consulting Engineers, Inc. (Ford Engineers) developed and demonstrated a method for estimating the benefit of the levee inspection program that the California Department of Water Resources (DWR) carries out on over 1,600 miles of levees in the Central Valley. Ford Engineers measured the benefit of DWR’s levee inspection program by computing the reduction in flood risk attributable to levee flood fighting and maintenance activities—the activities that result directly from the inspection program.
Specifically, Ford Engineers assessed flood risk reduction as economic damage avoided and reduction in statistical lives lost (SLL) due to flood fighting at four sites and attributable to levee maintenance at five sites. In addition, at one of the sites for levee maintenance assessment, ecosystem benefit was assessed as the reduction in the acreage of giant garter snake habitat. This risk assessment employed available tools and information common to planning studies.
The study found that levee maintenance reduces expected annual damage, SLL, and expected annual loss of habitat acreage. Similarly, the study found that flood fighting reduces expected annual damage and SLL. The study developed and applied successfully a systematic, repeatable, and understandable procedure for assessing risk reduction attributable to flood fighting and levee maintenance activities, using expert opinion elicitation to provide information otherwise unattainable. This procedure can be applied to other facilities of the State Plan of Flood Control (SPFC) to assess the benefit of DWR programs.