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