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<br />') <br /> <br />CHAPTER VI <br /> <br />CALCUIATION OF PHYSICAL FLOOD DAMAGE <br />UNDER FUTURE CONDITIONS WITHOUT-PROJECT <br /> <br />OVERVIEW OF THE PROCESS <br /> <br />This chapter outlines the procedures used to account for all changes <br /> <br />that would occur during the period of analysis if no project were <br /> <br />undertaken in response to the study. According to ~, "'future' is any <br /> <br />time period after the year in which the study is completed" (P&G, p. 36). <br /> <br />The period of analysis is defined as the project life, which is usually 50 <br /> <br />or 100 years, depending on the type of flood damage reduction measure <br /> <br />being considered. The period of analysis begins with the base year, when <br /> <br />the project becomes fully operational. Due to the high degree of <br /> <br />) <br /> <br />uncertainty over time, all economic activity, demolgraphic, and hydraulic <br /> <br />characteristics are held constant after the 50th year. All benefits are <br /> <br />discounted to the base year. A large discount rate can greatly reduce the <br /> <br />effect of any future changes on the overall project benefits. <br /> <br />This chapter describes how changes in land use, economic activity, <br /> <br />and physical setting can affect flood damages. Projections have two major <br /> <br />purposes: 1) to determine how changes in drainage patterns, that occur as <br /> <br />a result of physical development, will affect elevation-frequency <br /> <br />relationships; and, 2) to determine how changes in development and <br /> <br />economic activity will affect elevation-damage relationships. These two <br /> <br />relationships are combined to estimate damages under future without- <br /> <br />project conditions. Hydrologic, demographic, and economic changes are <br /> <br />) <br /> <br />VIol <br />