Processing ArcHydro Datasets with NHDPlus Version 2, Emphasizing StreamStats Data Development

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Processing ArcHydro Datasets with NHDPlus Version
2, Emphasizing StreamStats Data Development

• Webinar SeriesPart 4 StreamStats-specific
  Datasets and Tools
• Alan Rea and Pete Steeves
• ID and MA-RI Water Science Centers

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Webinar Series Overview

• May 9Concepts and Preprocessing
• May 23ArcHydro Data Development
• June 6Basin Characteristics
• June 19StreamStats-specific Datasets and Tools

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Course Web Site

• http//streamstats09.cr.usgs.gov/DataPrepWorkshop/
  Workshop2012/

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Todays Agenda

• Discussion of Exercise 3
• Regression regions setup and processing
• Exclusion polygons setup and examples
• NHD Navigation tools
• Demonstration
• Take-home exercise (optional)

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Discussion of Exercise 3
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Regression Regions

• Many states are divided into regions with
  different regression equations
• In general, these regions are defined based on
  the set of gages that were used in the regression
  analysis
• Often there is no region polygon feature class
  developed
• You need to develop one

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Regions

• Peak-flow and bankfull equations

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Region Dataset Preparation

• We actually need a grid, with the values being
  the NSS region ID
• The NSS region IDs can change, so give us a grid
  having regions matching your regression report
• Must run RegionsPrepro to compute percent areas
  for regions by hucpoly

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Which to show on the web?
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Exclusion Polygons

• Used as an initial test before delineation
• If delineation point falls in an exclusion
  polygon 2 possibilites
• ExcludeCode 1 No delineation allowed
• ExcludeCode ? 1 Delineation with warning

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Exclusion PolygonsAdvanced Treatment

• It is possible to have even more control with
  exclusion polygons
• For example, you can set it up so in certain
  areas only peak flows will be run, but not low
  flows
• The mechanics of this are difficult to explain
• Ask for more details if you need this