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2024 Hennepin County All -Jurisdiction Hazard Mitigation Plan <br />Volume 2 — Hazard Inventory <br />�Hazard Assessment: DROUGHT <br />4.3.8.1. Definition <br />A generalized definition of drought is a period of <br />abnormally dry weather sufficiently prolonged for the <br />lack of water to cause serious hydrologic imbalance in <br />. u <br />the affected area. In easier to understand terms, a <br />drought is a period of unusually persistent dry weather��� <br />that persists long enough to cause serious problems ' <br />such as crop damage and/or water supply shortages <br />If the drought is brief, it is known as a dry spell, or <br />partial drought. A partial drought is usually defined as <br />more that 14 days without appreciable precipitation, <br />whereas a drought may last for years. Another type of drought is a flash drought, which is a "rapid onset <br />or intensification of drought [... ] set in motion by lower -than -normal rates of precipitation, accompanied <br />by abnormally high temperatures, winds, and radiation" (MIDIS, 2024). When a drought begins and ends <br />is difficult to determine because rainfall data alone won't tell you if you are in a drought, how severe your <br />drought may be, or how long you have been in drought. <br />The most used drought definitions are based on meteorological, agricultural, hydrological, and <br />socioeconomic effects: <br />1. Meteorological — A measure of departure of precipitation from normal. Due to climatic <br />differences, what might be considered a drought in one location of the country may not be a <br />drought in another location. <br />2. Agriculture — Refers to a situation where the amount of moisture in the soil no longer meets the <br />needs of a particular crop. <br />3. Hydrological — Occurs when surface and subsurface water supplies are below normal. <br />4. Socioeconomic— Refers to the situation that occurs when physical water shortages begin to affect <br />people. <br />4.3.8.2. Range of Magnitude <br />The severity of the drought depends upon the degree of moisture deficiency, the duration, and the size <br />of the affected area. The magnitude of a considered drought event corresponds to the cumulative water <br />deficit over the drought period, and the average of the cumulative water deficit over the drought period's <br />mean intensity. <br />• Most Severe Drought: 1030-1936 Dust Bowl or 'Dirty Thirties' <br />• Longest Drought: 1944-1950s: Southwestern United States <br />• Costliest: Second to the Dust bowl that is estimated to have cost $1 billion in 1930's money is the <br />drought of 1989 and 1999. It is estimated the drought costs somewhere between $80 and $120 <br />billion worth in damage. <br />143 <br />