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SOCRATES ERASMUS Intensive Programme

ArcHYDRO: GIS for Water Resources
Source: Center for Research in Water Resources, University of Texas at Austin

Tutorial: Watershed and Stream Network Delineation
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Goals of the Exercise
The purpose of this exercise is to illustrate, step-by-step, how to use the majorfunctionalities available in the Arc Hydro tools for Raster Analysis. You will perform drainage analysis on a terrain model for the San Marcos Basin. The Arc Hydro tools are used to derive several data sets that collectively describe the drainage patterns of the catchment. Raster analysis is performed to generate data on flow direction, flow accumulation, stream definition, stream segmentation, andwatershed delineation. The utility of the Arc Hydro tools is demonstrated by applying them to develop attributes that are useful for hydrologic modeling. ____________________________________________________________

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Main Steps
Exploring the DEM … Developing Terrain Preprocessing: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. DEM Reconditioning Fill Sinks Flow Direction Flow AccumulationStream Definition Stream Segmentation Catchment Grid Delineation Catchment Polygon Processing Drainage Line Processing Drainage Density Evaluation

HydroEurope 2007/2008 – W. Berolo

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ArcHYDRO / Watershed and Stream Network Delineation

Available Data
The data are provided in the accompanying zip file, Data.zip. The data files used in the exercise consist of DEM grid for the San MarcosBasin in Texas and the hydrography data. Data.zip contains a data folder with the raw DEM named smdem_raw (from the NED – National Elevation Dataset of the United States), and a geodatabase named NHD.mdb (National Hydrography Dataset). Inside NHD.mdb, you will be interested in NHDFlowline and NHDPoint feature classes stored in Hydrography feature dataset.____________________________________________________________

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Procedure
Exploring the DEM …
i. Open ArcMap and load Arc Hydro tools

HydroEurope 2007/2008 – W. Berolo

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ArcHYDRO / Watershed and Stream Network Delineation

Open ArcMap. Create a new empty map, and save it as Exercise.mxd (or any other name – Ex3 is the name used in this tutorial). Right click on the menu bar to pop up the context menushowing available tools as shown below.

Check the Arc Hydro Tools menu. If the Arc Hydro Tools menu does not appear in the list, click on “Customize” (Scroll down the list to see “Customize”). In the Customize dialog that appears, check the Arc Hydro Tools box.

You should now see the Arc Hydro tools added to ArcMap as shown below. You can leave it floating or you may dock it in ArcMap.HydroEurope 2007/2008 – W. Berolo

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ArcHYDRO / Watershed and Stream Network Delineation

Note that it is not necessary to load the Spatial Analyst, Utility Network Analyst, or Editor tools because Arc Hydro Tools will automatically use their functionalities on as needed basis. These toolbars need to be loaded though if you want to use any general functionality that they provide (such asgeneral editing functionality or network tracing). However, the Spatial Analyst Extension needs to be activated, by clicking Tools > Extensions…, and checking the box next to Spatial Analyst.

ii. Data Setup
The existing NHD data to be used in this exercise are stored in a geodatabase and loaded in the map. All vector data created with the Arc Hydro tools will be stored in a new geodatabase thathas the same name as the stored project or ArcMap document (unless pointed to an existing geodatabase) and in the same directory where the project has been saved (your folder for Ex3). By default, the new raster data are stored in a subdirectory with the same name as the dataset or Data Frame in the ArcMap document (called Layers by default and under the directory where the project is stored)....
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