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Explains about how to create Drainage step by step.
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Drainage generation using ArcGISDrainage generation using ArcGIS
Ashok Peddi
Add Digital Elevation Model image to ArcMap
Open Tools Extensions and verify that the Spatial Analyst function is available and checkedSpatial Analyst function is available and checked.
Calculate the Aspect using Surface Analysis tool in Spatial Analyst tools
• Select Spatial Analyst Surface Analysis AspectAnalysis Aspect on the Spatial Analyst toolbar. At the dialog that appears select Digital Elevation Model image as the input surfaceinput surface.
• Click on ok .
Generating Aspect
Calculate Flow Direction
• Assign a flow direction to each grid cell based on the neighboring cell with the lowestbased on the neighboring cell with the lowest elevation
O h T lb O A T lb l• Open the Toolbox . Open ArcToolbox, select Spatial Analyst Tools Hydrology Flow Di i d bl li k Fl Di iDirection, double click on Flow Direction. Give the DEM as Input
Flow Direction
Calculate Flow AccumulationCalculate Flow AccumulationFlow accumulation is calculated from flow directionsdirections.It calculates the number of grid cells drain into an individual grid cell
• With ArcToolbox
individual grid cell
With ArcToolbox open, select Spatial Analyst Tools HydrologyHydrology Flow Accumulation, double click onFlowFlow Accumulation
Flow DirectionFlow Direction
Drainage line processingDrainage line processing
• Now we will use ArcHydro to• Now we will use ArcHydro to generate drainage line(if you don’t have ArcHydero tools for ArcGISdownload it fromhttp://www.crwr.utexas.edu/gip gs/archydrobook/ArcHydroTools/Tools.htm.
• Please close the ArcGIS before running the Arc Hydro tools. Once installation process is over please verify whether the ArcHydro tool bar is enable or not.
• To verify go to tools and customize
• Check the ArcHydro tools to enable yin the ArcMap main window
E bl d A H d lEnabled ArcHydro tools
To generate Drainage line first we need to find out t d fi ti i A H d t lstream defination using ArcHydro tools
• Stream DefinitionStream Definition
• This step generates stream grid from stream accumulation gridfrom stream accumulation grid.
• From ArcHydro tool bar, select T i P i STarrain Preprocessing – Stream Definition. Use FlowAcc as flow
l i id Saccumulation grid, Str as stream grid to be generated.
Enter river threshold as per your requirement
Stream SegmentationStream Segmentation
• Stream segmentation generate a grid of stream segments from fl di ti id d tflow direction grid and stream grid created from stream definition processing. p g
• Input the dialog as following. FlowDir as the flow direction grid and Str as the Stream Gridgrid and Str as the Stream Grid. Output link grid will be Lnk.
Drainage line processing
Thi t th• This process converts the stream link grid into a drainage line feature class that gwe are familiar with (we normally represent rivers, streams as line features)streams as line features).
• Select Terrain Preprocessing –Select Terrain Preprocessing Drainage Line Processing. Input the dialog as following:
• Drainage line is ready.• End of the document.