Hi! Welcome to my Channel! I will show you how to calculate catchment area using Arc GIS software in this video You need a Digital Elevation Model (DEM) file to calculate catchment area DEM file can be downloaded from the link provided in the description Select required region from download page I have downloaded region which covers a portion of Nepal I have used Arc GIS Version 10.3 to calculate catchment area in this video Click on Catalog in lower right If you don’t find it, select it from Menu bar by clicking on window and then catalog On Catalog, click on Connect to Folder and select the location for folder containing DEM file which you have downloaded Now, connected folder is displayed in catalog, right click on selected folder which displays available DEM file and Select required DEM file Next, create a folder where you want to save your work. I have created a folder with name Catchment Connect folder Catchment to your catalog Right click folder you just connected, hover to New, and then Shape File A new dialog box “Create New Shape File” appears Enter name, and select feature type to point, click on edit to select the co-ordinate system to WGS 1984 On Left in layers, the shape file appears Right click on shape file, hover to edit features and click on start editing In create features on the right, click on intake or name you have given Hover mouse anywhere in working panel over the map and right click and select absolute X Y Define the co-ordinates of intake in either units available from the drop down menu Click on Editor and Stop editing Zoom in the map to appropriate size such that the total catchment area falls in the zoomed view Search for Clip in the right and select Clip Data Management Select the original DEM file in Input raster, click on environment, processing extent and then select same as display in extent dropdown menu A new clip will appear in layers which you can see in left. This will be the working layer now. You can turn off visibility of other layers. You can also change the size shape file appears Go to Search and search fill Select Fill Spatial analyst, select clip in input surface raster, and give the filename of your choice to save it in folder you defined earlier Search flow direction and select flow direction spatial analyst. Select fill in input surface raster, define filename and location to be saved Search flow accumulation and select flow accumulation spatial analyst. Give path to flow direction raster, file name for flow accumulation raster If the shape file does not lie in the stream itself, you can drag it to necessary location. Click on Editor, Start Editing and select the shape file When you have moved it to desired location, click on Editor and stop editing Search Snap Pour Point and input shape file as pour point data, and flow accumulation raster , give desired name in output raster Search for watershed and input flow direction raster, pour point data, defined output Raster appears which should be converted to polygon to calculate the area Search for raster to polygon conversion tool and select the watershed as input raster, define the output file name and location Polygon shape file appears. You can change its appearance using available options Right click on polygon in layers on left and select open attribute table. Click on add field, give name and select precision level Right click on defined name and select calculate geometry In this case, a projected coordinate system has to be created Click on View , Data frame properties in Menu bar Click on New Projected Coordinate System. Define Name, false easting, central meridian and scale factor. Select unit type and click OK. Select new PCS and click Apply , OK On attribute table, Right click area and calculate geometry Catchment can be viewed in Google Earth tool. Search for layer to KML Define shape file you want to export and save filename and location Open the KML file browsing saved directory, and you can view it in google earth THANK YOU FOR WATCHING!
