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Drought

Drought. Relevance . Case Studies India Australia Western United States. Table 1: Drought & Sustainability by Dave Chaney & Chuck Ingels , SAREP, Spring, 1991 (v3n3), sustainable agriculture. www.strangecosmos.com/. www.waterencyclopedia.com. earthobservatory.nasa.gov. Background.

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Drought

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  1. Drought

  2. Relevance • Case Studies • India • Australia • Western United States Table 1: Drought & Sustainability by Dave Chaney & Chuck Ingels, SAREP, Spring, 1991 (v3n3), sustainable agriculture www.strangecosmos.com/ www.waterencyclopedia.com earthobservatory.nasa.gov

  3. Background • What is drought ? • Physical phenomena: compression warming (or sinking of air) which inhibits cloud formation

  4. Background • What is drought ? • Physical phenomena: compression warming (or sinking of air) which inhibits cloud formation • Defined by impacts: • Meteorological • Hydrologic • Socioeconomic • Agricultural

  5. Background • How is drought quantified? • Drought indices: varied metrics that integrate drought characterisitics • Percent of Normal • SPI • SWSI • RDI • Deciles • CMI • PDSI • Drought Monitor http://drought.mssl.ucl.ac.uk/graphics/drought_class3.png

  6. Life of a drought (LAD) • How frequent are droughts?

  7. Life of a drought (LAD) • How frequent are droughts? • Where will a drought live?

  8. Life of a drought (LAD) • How frequent are droughts? • Where will a drought live? • How intense is the drought? • How long will a drought live?

  9. Data Set • PDSI • Texas region 7 • Monthly from 1900-2009 • http://gis.ncdc.noaa.gov/website/ims-cdo/div/viewer.htm

  10. Data Set • PDSI • Texas region 7 • Monthly from 1900-2009 • Drought Monitor • Shape Files • Texas • USA • Weekly from 2000-2009 • 0 to 4 • http://gis.ncdc.noaa.gov/website/ims-cdo/div/viewer.htm

  11. Statistical Methods • Descriptive statistic s • Mean, max and min • Regression • Trends with droughts over time • Multivariable regression • Trends with precipitation and temperature • Probability distribution • Test for normality • Chi squared • Cumulative Distributions • Normal and Poisson

  12. Analysis: PDSI • Trends? • Regression Results

  13. Analysis: PDSI • Is the data Normal? • Chi Squared test Mean = 0; STDV = 2.5 Theoretical: 1222 ; Observed: 47OK Cannot reject null hypothesis with 95% confidence

  14. Analysis: PDSI • Normal probability density function • Drought < -3 • Prob [ X< -3] = 13% • Is the data Normal? Mean = 0; STDV = 2.5 Theoretical: 1222 ; Observed: 47OK Cannot reject null hypothesis with 95% confidence

  15. Analysis: PDSI • Prob [ X< -3] = 13% • Poisson distribution

  16. Analysis: PDSI • PDSI • How long does a drought live? • μ = 5 months (invlog) • Is the data Lognormal? Theoretical: 41; Observed: 10 OK Cannot reject null hypothesis with 95% confidence

  17. Analysis: Drought monitor • Texas • Austin

  18. Analysis: Nov ‘07 to May ’09

  19. Analysis: Drought Monitor • > D2 (severe-exceptional) Average: 18%

  20. Analysis: Drought Monitor • > D2 (severe-exceptional) Average: 18% Average: 18%

  21. Analysis: Drought Monitor • > D2 (severe-exceptional) Average: 18% Average: 18% Average: 10%

  22. Conclusion • No statistically significant temporal trends • 13% chance that a severe drought will occur in any given month • Average area covers 18% of the state (similar to national average)

  23. Conclusion • No statistically significant temporal trends • 13% chance that a severe drought will occur in any given month • Average area covers 18% of the state (similar to national average) • Future Work • Seasonal variations • El Nino • More spatial analysis of the drought monitor

  24. Question Yeah…I’m hot, So?

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