1. Lecture 22: Using ArcToolbox Tools in Python
Jeffery S. Horsburgh
CEE 5190/6190
Geographic Information Systems for Civil Engineers
Spring 2016

2. Objectives
Create a Python script that automates a complex geoprocessing task not easily accomplished with core GIS software functionality
Introduction to the Python programming language
Write and execute computer code to automate repetitive tasks
Become proficient in the use of GIS tools to conduct spatial analyses

3. Python Programming Challenge
Using the DEM and outlet shapefile provided, write a Python script that extracts streams and delineates the watershed above the outlet
Fill pits
Calculate flow direction raster
Calculate flow accumulation raster
Extract stream network raster (Threshold = 500)
Snap outlet point to outlet raster
Delineate watershed raster
Convert watershed raster to polygon
Run the tools from ArcToolbox and copy the code
Generate one .py script file and save
Load and execute in ArcMap Python window

4. Result Watershed

5. Hints
If you run the tools and create the datasets, you will have to delete them before you try to run your script or you will get errors
Check to make sure the geoprocessing Environment setting “Processing Extent” and “Snap Raster” are set to process the extent of the NED grid