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Understanding Drought

Understanding Drought. Gloria Forthun Regional Climatologist Southeast Regional Climate Center. Drought Characteristics. Drought Characteristics. Normal part of climate variability. Drought Characteristics. Normal part of climate variability No universal definition.

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Understanding Drought

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  1. Understanding Drought Gloria Forthun Regional Climatologist Southeast Regional Climate Center

  2. Drought Characteristics

  3. Drought Characteristics • Normal part of climate variability

  4. Drought Characteristics • Normal part of climate variability • No universal definition

  5. Drought Characteristics • Normal part of climate variability • No universal definition • Complex – interdisciplinary

  6. Drought Characteristics • Normal part of climate variability • No universal definition • Complex – interdisciplinary • Impacts can be economic, social, environmental

  7. Drought Characteristics • Normal part of climate variability • No universal definition • Complex – interdisciplinary • Impacts can be economic, social, environmental • Impacts can linger for years

  8. Drought Vs. Other Natural Disasters

  9. Drought Vs. Other Natural Disasters • Onset and end of drought is difficult to determine

  10. Drought Vs. Other Natural Disasters • Onset and end of drought is difficult to determine • No precise and universally accepted definition of drought

  11. Drought Vs. Other Natural Disasters • Onset and end of drought is difficult to determine • No precise and universally accepted definition of drought • Nonstructural impacts and spread over a large geographic area

  12. Types of Drought

  13. Types of Drought • Common to all droughts is that they originate from a deficiency of precipitation that results in water shortage for some activity or for some group. National Drought Mitigation Center

  14. Types of Drought • Meteorological Drought

  15. Types of Drought • Meteorological Drought • Measured in terms of the degree of dryness (intensity) and the duration of the dry period

  16. Types of Drought • Meteorological Drought • Measured in terms of the degree of dryness (intensity) and the duration of the dry period • Region Specific

  17. Types of Drought • Agricultural Drought

  18. Types of Drought • Agricultural Drought • Meteorological drought that impacts agriculture

  19. Types of Drought • Agricultural Drought • Meteorological drought that impacts agriculture • Usually the first economic sector to be hit

  20. Types of Drought • Agricultural Drought • Meteorological drought that impacts agriculture • Usually the first economic sector to be hit • Precipitation shortages, ET, soil moisture, etc…

  21. Types of Drought • Agricultural Drought • Meteorological drought that impacts agriculture • Usually the first economic sector to be hit • Precipitation shortages, ET, soil moisture, etc… • Plant water demand versus available soil moisture

  22. Types of Drought

  23. Types of Drought • Hydrologic Drought

  24. Types of Drought • Hydrologic Drought • Impacts of rainfall shortages on the hydrologic system (groundwater, rivers, lakes, reservoirs)

  25. Types of Drought • Hydrologic Drought • Impacts of rainfall shortages on the hydrologic system (groundwater, rivers, lakes, reservoirs) • Communities vary in degree of vulnerability depending on their water source

  26. Types of Drought • Hydrologic Drought • Impacts of rainfall shortages on the hydrologic system (groundwater, rivers, lakes, reservoirs) • Communities vary in degree of vulnerability depending on their water source • Connections between basins, regions affect other regions

  27. Types of Drought • Hydrologic Drought • Impacts of rainfall shortages on the hydrologic system (groundwater, rivers, lakes, reservoirs) • Communities vary in degree of vulnerability depending on their water source • Connections between basins, regions affect other regions • Out of phase or lag meteorological drought

  28. Source: National Water and Climate Center

  29. Types of Drought • Socio-economic drought

  30. Types of Drought • Socio-economic drought • Demand exceeds supply of some economic product as a result of weather-related low precipitation event(s)

  31. Types of Drought • Socio-economic drought • Demand exceeds supply of some economic product as a result of weather-related low precipitation event(s) • Precipitation or water represents SUPPLY, which varies by sector, DEMAND can be for products or for the water itself

  32. Types of Drought • Socio-economic drought • Demand exceeds supply of some economic product as a result of weather-related low precipitation event(s) • Precipitation or water represents SUPPLY, which varies by sector, DEMAND can be for products or for the water itself • Occurs more frequently • change in how often or long a drought occurs • in the vulnerability within society • or both

  33. Differences Between Droughts

  34. Differences Between Droughts • Intensity • Degree of precipitation deficit and/or severity of impacts

  35. Differences Between Droughts • Intensity • Degree of precipitation deficit and/or severity of impacts • Departure of a climate index from normal; linked to duration to determine impacts

  36. Differences Between Droughts • Duration

  37. Differences Between Droughts • Duration • Seasonal • Single-year • Multiple-years

  38. Differences Between Droughts • Duration • Seasonal • Single-year • Multiple-years • Multiple timescales • Example: • Year One – below normal • Year Two -- near normal; timing off for crop demand • Year Three – near normal; not enough to recover from hydrologic drought.

  39. Differences Between Droughts • Spatial Extent

  40. Differences Between Droughts • Spatial Extent • Regional in nature • Result of large scale anomalies in atmospheric circulation patterns

  41. Differences Between Droughts • Spatial Extent • Regional in nature • Result of large scale anomalies in atmospheric circulation patterns • One or more regions, one or more states

  42. Differences Between Droughts • Spatial Extent • Regional in nature • Result of large scale anomalies in atmospheric circulation patterns • One or more regions, one or more states • Can shift from season to season

  43. Risk and Vulnerability

  44. Risk and Vulnerability • Hazard: Probability of occurrence, within a specified area and time, of a potentially damaging natural event (drought) Wilhite, 1997

  45. Risk and Vulnerability • Hazard • Vulnerability: Characteristics of people, activities, or the environment that makes them susceptible to the impacts of drought; measure of the ability to anticipate, cope with, resist, and recover from the impacts of drought Wilhite, 1997

  46. Risk and Vulnerability • Hazard • Vulnerability • Risk: Result of exposure to hazard and vulnerability

  47. Drought Reduction in rainfall over an extended period of time Social Component Demand exceeds Supply Intensity Duration Spatial Extent Natural Hazard Vulnerability RISK

  48. Monitoring Drought • Why should we monitor drought?

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