GIS Tutorial for Watershed Delineation CEE 577, Spring 2013 Liz Isenstein Objective: Learn how to delineate a watershed for a point of interest using a digital elevation model (DEM) and the ArcGIS Spatial Analyst Extension Background: A digital elevation model (DEM) is a regularly spaced grid of numbers representing elevation – using DEM and spatial analyst tools in ArcGIS. Abstract. In this workflow the parameter has been set (not shown) to mark a single watershed. Watershed management field manual Watershed survey and planning. Watershed Result Step 10 – Create watersheds (Shapefile) Now that you have your watershed delineated in raster format, you can convert this to a shapefile with the basins as individual polygons. The grid processor needs three grid layers: pour points, flow accumulation, and flow direction. The last function to run is Watershed Grid to Shapefile. Many of these tools are not activated until other requirements are met; often this requirement is to have used other tools in this menu. How To: Create a watershed model using the Hydrology toolset Summary. This area can be delineated from a digital elevation model (DEM) using the Hydrology toolset from the Spatial Analyst toolbox. The watershed boundaries do a … The Stream Reach and Watershed function also has the option to delineate subwatersheds draining to each stream reach. •Mark the high points adjacent to the water body •Connect the marks; always cross a contour line at right angle (perpendicular). Procedure Start with a “lakeshed”; the land area contributing (draining) to a lake. Coordinate System For watershed delineation functions, the menu serves as a roadmap: the workflow proceeds from top to bottom in order. List of Examples. If you are using this tutorial as a guide for another datasets or watershed, make sure that your DEM covers larger area than just the watershed boundary. Downloading and Importing Gauge station location (Point Data) 2. A watershed is an upslope area that contributes water flow as concentrated drainage. 55 Watersheds in GIS Definition (Hydrologic): A watershed is a contiguous region of land that all drains to a single location called the watershed outlet. Do not use a DEM that is clipped exactly to the watershed … In the recent year’s advances in terrain data collection techniques, most notable Light Detection and Ranging (LiDAR), computing power, and geographical information systems (GIS… The outlet, or pour point, is the point on the surface at which water flows out of an area. 1. We will also delineate the watershed using online delineating tools. It is the lowest point along the boundary of a watershed. Watershed components. The last step in watershed delineation is to perform the function itself. 1.2 Definitions Delineating watersheds. Various GIS tools are available under the GIS menu (Figure 1). Watersheds can be delineated from a DEM by computing the flow direction and using it in the Watershed tool. Introduction and concepts. Visualizing the landscape represented by the topographic map will make the process much easier than simply Downloading the DEM and NHD data from ESRI Online Sources 3. • In the toolbox, navigate to Conversion Tools → From Raster → Raster to Polygon • Choose sl_watersheds as the input raster. The processing will include: 1. delineating watersheds by using any pre-processing tool. 9. Delineating Exercise 1. 1.1 The need for watershed survey and planning. Extracting the DEM data 4. Here are the contour lines placed atop the watersheds. Definition (GIS): A watershed is the set of al pixels whose downstream flowpath passes through a selected (outlet) pixel. Delineating watersheds. outputs a vector stream network shapefile and grid representing the watershed as a whole. by T.C. Delineating a Watershed The following procedure and example will help you locate and connect all of the high points around a watershed on a topographic map shown in Figure F-4 below. Foreword. sewer, or combined systems involves delineating catchments and overland flow paths. Introduction. Delineating the Watershed from DEMs 5. Sheng FAO CONSERVATION GUIDE 13/6 FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS Rome, 1990 TABLE OF CONTENTS.