Local mitigation strategy (LMS) - Volusia County Government

SECTION 5: HAZARD PROFILES5.9 DROUGHT5.9.1 BackgroundDrought is a normal part of virtually all climatic regions, including areas with high and low averagerainfall. Drought is the consequence of a natural reduction in the amount of precipitation expected overan extended period of time, usually a season or more in length. High temperatures, high winds, and lowhumidity can exacerbate drought conditions. In addition, human actions and demands for waterresources can hasten drought-related impacts. Droughts are typically classified into one of four types 9 : Meteorological: The degree of dryness or departure of actual precipitation from an expectedaverage or normal amount based on monthly, seasonal, or annual time scales. Hydrologic: The effects of precipitation shortfalls on stream flows and reservoir, lake, andgroundwater levels. Agricultural: Soil moisture deficiencies relative to water demands of plant life, usually crops. Socioeconomic: The effect of demands for water exceeding the supply as a result of a weatherrelatedsupply shortfall.Droughts are slow-onset hazards, but over time can have very damaging affects to crops, municipalwater supplies, recreational uses, and wildlife. If droughts extend over a number of years, the directand indirect economic impact can be significant.5.9.2 Location and Spatial ExtentThe Palmer Drought Severity Index (PDSI) is based on observed drought conditions and range from -0.5 (incipient dry spell) to -4.0 (extreme drought). Evident in Figure 5.9, the Palmer Drought SeverityIndex Summary Map for the United Stated, droughts affect most areas of the United States, but areless severe in the Eastern United States.Drought typically covers a large area and cannot be confined to any geographic or politicalboundaries. According to the Palmer Drought Severity Index (Figure 5.9), Florida has the relativelylow risk for drought hazard. However, local areas may experience much more severe and/orfrequent drought events than what is represented on the Palmer Drought Severity Index map.Further, it is assumed that Volusia County would be uniformly exposed to drought, making thespatial extent potentially widespread. Periods of drought can exacerbate the ignition of wildfiresthat can damage the natural and built environment, as has occurred before in Volusia County.9 Multi-Hazard Identification and Risk Assessment: A Cornerstone of the National Mitigation Strategy, FEMAVolusia County Multi-jurisdictional Local Mitigation StrategyFebruary 20105:44