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GIS and Drought Applications

GIS and Drought Applications. Keith Stellman Senior Hydrologist Lower Mississippi River Forecast Center Slidell, LA. Outline. Overview of CPC products History/Background info/Examples Validity of the Data Gridded Normals? Compositing Possibilities. Normal CPC Drought Graphics.

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GIS and Drought Applications

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  1. GIS and Drought Applications Keith Stellman Senior Hydrologist Lower Mississippi River Forecast Center Slidell, LA

  2. Outline • Overview of CPC products • History/Background info/Examples • Validity of the Data • Gridded Normals? • Compositing • Possibilities

  3. Normal CPC Drought Graphics

  4. CPC Graphics Cont’

  5. CPC Graphics Cont.

  6. Overview / History • Stage III • 4 x 4 km resolution • Gridded PRISM data • ABRFC • Computed daily average from PRISM data • Posted output images to web • LMRFC • Converted prism grids to HRAP projection in GIS • Computed monthly images on 1st of the month

  7. CPC Percent of Normal

  8. RFC Graphics1 Month Stage III

  9. RFC Graphics

  10. WGRFC/ABRFC/OHRFC Examples

  11. Detailed RFC Images

  12. Details, Details • County to county rainfall surplus/deficits • Grid to grid comparisons • Water supply issues from county to county

  13. RFC Observed Analysis • Daily rain gage analysis in GIS using IDW method of interpolation on 4x4 km grid • Grids are archived • Grids are summed for monthly totals • Rain gage analysis can then be used for percent of normal

  14. Observed Analysis1 Month Totals

  15. LMRFC Observed Analysis

  16. Comparisons Minimums

  17. How Accurate is the Data?1 month totals for October 2002

  18. What is Normal? • PRISM (Parameter-elevation Regressions on Independent Slopes Model) • Knowledge-based system using point data, digital elevation model, & other spatial data sets • Generates gridded estimates of climatic parameters (such as precipitation & temperature) • Accounts for rain shadows, inversions, coastal proximity, and others

  19. Orographic Enhancement

  20. PRISM Maps

  21. Where Can I Find PRISM Data? • Digital via Web Sites SCAS: www.ocs.orst.edu/prism/ NRCS: www.ftw.nrcs.usda.gov/prism/prism.html Contact Info: Christopher Daly Director Spatial Climate Analysis Service Oregon State University Corvallis, Oregon

  22. How do we get the results • PRISM data is on a 4x4 km grid • Stage III data is on a 4x4 km grid • ((((StageIII-Prism)/Prism)+1)*100) = % of Normal Precipitation • GIS Software does grid calculations and exports result as a JPEG • Program is automatically run on 1st of the month for previous 1,2,3 and 6 months

  23. Who is doing what? • ABRFC,WGRFC,LMRFC,OHRFC,CBRFC • Utilize gridded datasets • CBRFC lists under water supply in form of pdf document • MBRFC,NERFC and MARFC • Utilize observed datasets on larger scale • MBRFC uses pdf document under water supply

  24. Composite • Southern Region RFC Web Team • Goal is to composite graphics with levels of zoom • Each SR RFC (SERFC,WGRFC,LMRFC,ABRFC) sends daily StageIII totals to WGRFC • Data is summed into monthly totals and compared to PRISM data

  25. Coming Very Soon!

  26. Future Possibilities • Providing each monthly calculation as a shapefile or ascii grid • Incorporating more than SR RFC’s into the datasets • Utilizing gage only datasets across SR

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