Delineating Sub-Watersheds Using Terrain Analysis in ArcInfo Chris Klaube Landscape Ecology 704:450

➲ Objectives ➲ Rundown in ArcInfo Workstation ➲ Speedbumps / Caveats ➲ Results ➲ Discussion

The Task ➲ Delineate subwatershed boundaries using DEM and Contour layers ➲ HUC-23 to HUC-26 ➲ HUC- Hydrological Unit Code

The Watershed

Goals ➲ To compare stream layer derived from county with stream layer created from DEM ➲ To create a 2-ft Contour layer for the entire watershed

Data ➲ Original DEM and Contour layers from NJDEP ➲ Monmouth County provided original stream layer

ArcInfo Commands import project fill flowdirection flowaccumulation *streamnet streamorder streamlink streamline watershed

streamnet ➲ Set threshold for the flow accumulation at several different values in order to create a stream layer with the right intricacy ➲ Usage streamnet = con(flowacc>2000, 1) ➲ Set at: 2, ,000 – 500

Stream Layers

Creating Contours ➲ Original Contour layer used to delineate HUC-polygons was at a 10-ft interval ➲ Used ArcInfo to create 2-ft interval contour ➲ Usage: LATTICECONTOUR {base_contour} {contour_item} {weed_tolerance} {z_factor}

Caveats ➲ New layers created by ArcInfo were in UTM projection ➲ Used ArcMap and ArcCatalog to redefine in NJ Stateplane  Arc Toolbox  Data Management Tools  Projections and Transformations ➲ New Contours begin at elevation ‘0’

References ➲ ESRI GIS and Mapping: Support Center