How to generate a perennial stream network

Utah stream network process

• Download NHD data for Utah from TMN Download v2

  • Include Utah as part of the Map Extent

  • Under the Data section, check “Hydrography (NHDPlus HR, NHD, WBD)”

  • Under Subcategories, only check “National Hydrography Dataset (NHD)”

  • Under Data Extent, check “State”

  • Under File Formats, check “Shapefile”

  • Click on “Search Products”

  • Click “Download Link (ZIP)” for the USGS National Hydrography Dataset Best Resolution (NHD) - Utah (published 20230505) Shapefile

• Create NHD Stream network

  • Load NHDFlowline shapefile into QGIS

  • NHD categorizes different types of reaches using FCodes, we need to select the FCodes for perennial, artificial paths, and connectors

    • A list of FCodes can be found here

  • Open up attribute table for NHDFlowline and click on “Select features using an expression”

• Type the following code then click Select Features

“fcode” IN (‘55800’,’33400’,’46006’)

• Use the Extract selected features tool to create a new shapefile with only perennial, artificial path, and connector features

• Right click output and go to Export > Save Features As…, save as ESRI Shapefile with name of NHDFlowline_STATE_ArtificialPathsConnectorsPerennial

• Short segment shapefile - removed connectors that were shorter than .5km

  • Select by expression

    • “lengthkm” < 0.5 AND “fcode” = ‘33400’

  • Invert selection

  • Extract selected features

  • Export file