Drainage generation using_arc_gis
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This document describes how to generate a drainage line in ArcGIS using spatial analyst and ArcHydro tools. It involves calculating the aspect, flow direction, and flow accumulation from a digital elevation model, then using ArcHydro tools to define streams, segment streams into grids, and convert the stream links grid into vector drainage line features. The key steps are 1) preparing elevation and other raster data, 2) calculating hydrology rasters, and 3) using ArcHydro tools to extract and convert stream networks into vector drainage lines.
Drainage generation using_arc_gis
- 1. Drainage generation using ArcGIS Drainage generation using ArcGIS Ashok Peddi
- 5. Open Tools Extensions and verify that the Spatial Analyst function is available and checked function is available and checked.
- 6. Calculate the Aspect using Surface Analysis tool in Spatial Analyst tools • Select Spatial Analyst Surface Analysis Aspect Analysis Aspect on the Spatial Analyst toolbar. At the dialog that appears select Digital Elevation Model image as the input surface. input surface • Click on ok .
- 10. Calculate Flow Direction • Assign a flow direction to each grid cell based on the neighboring cell with the lowest based on the neighboring cell with the lowest elevation • O Open the Toolbox . Open ArcToolbox, select h T lb O A T lb l Spatial Analyst Tools Hydrology Flow Direction, double click on Fl Di i d bl li k Flow Direction. Di i Give the DEM as Input
- 12. Flow Direction
- 13. Calculate Flow Accumulation Calculate Flow Accumulation Flow accumulation is calculated from flow directions. directions It calculates the number of grid cells drain into an individual grid cell individual grid cell • With ArcToolbox With ArcToolbox open, select Spatial Analyst Tools Hydrology Hydrology Flow Accumulation, double click on Flow Flow Accumulation
- 16. Drainage line processing Drainage 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 ArcGIS download it p fromhttp://www.crwr.utexas.edu/gi g s/archydrobook/ArcHydroTools/Tool s.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 y in the ArcMap main window
- 17. Enabled ArcHydro E bl d A H d tools l
- 18. To generate Drainage line first we need to find out stream defination using ArcHydro t l t d fi ti i A H d tools • Stream Definition Stream Definition • This step generates stream grid from stream accumulation grid. from stream accumulation grid • From ArcHydro tool bar, select Tarrain P T i Preprocessing – S i Stream Definition. Use FlowAcc as flow accumulation grid, Str as stream l i id S grid to be generated.
- 21. Stream Segmentation Stream Segmentation • Stream segmentation generate a grid of stream segments from flow direction grid and stream fl di ti id d t grid created from stream definition processing. p g • Input the dialog as following. FlowDir as the flow direction grid and Str as the Stream Grid. grid and Str as the Stream Grid Output link grid will be Lnk.
- 23. Drainage line processing • Thi This process converts the t th stream link grid into a drainage line feature class that g we 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: