Drought occurs somewhere in the United States almost every year and results in serious economic, social, and environmental costs and losses. Drought is more commonly associated with the western United States because much of this region is typically arid to semiarid. For example, this region experienced widespread drought conditions from the late 1980s through the early 1990s. The widespread and severe drought that affected large portions of the nation in 1988 resulted in an estimated $39 billion in impacts in sectors ranging from agriculture and forestry to transportation, energy production, water supply, tourism, recreation, and the environment (Riebsame et al., 1991). In the case of agriculture, production losses of more than $15 billion occurred and especially devastated corn and spring wheat belts in addition to reducing exports to other nations. In 1995, the U.S. Federal Emergency Management Agency (FEMA) estimated annual losses attributable to drought at $6–8 billion (FEMA, 1995). Since 1995, drought has occurred in nearly all parts of the country, and many regions have been affected on several occasions and in consecutive years. Most of the eastern United States experienced an extremely severe drought in 1998– 99, and in parts of the southeast, drought occurred each year from 1999 through 2002, especially in Florida and Georgia. Figure 9.1 depicts nonirrigated corn yields for Nebraska for the period from 1950 to 2002. Nebraska is one of the principal agricultural states in the United States, and corn is one of its primary crops. The drought effects on yields are most apparent during the severe droughts of the mid-1950s, mid-1970s, 1980, 1983, 1988–89, and 2000. Extremely wet years, such as 1993 in the eastern part of the state, also depressed corn yields. Monitoring drought presents some unique challenges because of its distinctive characteristics (Wilhite, 2000). The purpose of this chapter is to document the current status of drought monitoring and assessment in the United States, particularly with regard to the agricultural sector.
