Hydrology in ArcGIS Pro, Lab Exercise 11: Finding the Shortest Path Through the Stream Network

In this lab exercise we will learn how to use the "Create Trace Network", "Enable Network Topology", and "Shortest Path" tools to build a trace network from our Streams that we created in Lab Exercise 7, and then to find the distance between two spring locations through that network.

We often want to know how far apart two features are, such as when we are worried or hopeful about the possibility of a species in one location successfully colonizing a nearby location. If this is an invasive species, then we hope the distances is great enough to prevent movement. If this is an endangered species we are trying to recover, then we hope the distance is short enough to allow the species to cross.

This kind of analysis is fairly easy to do when we just care about straight-line, “as-the-crow-flies” distances. However, not everything is able to travel in straight lines. If our species are fish, or some other aquatic obligate that cannot survive outside of wetlands and riparian corridors, then the distance between two sites should really be considered the distance through the hydrologic network.

ArcGIS Pro offers a way to generate this “Trace Network” from our streams, which can then be used to find the shortest path through that network. The tools are a little flaky; there are lots of steps, and most steps are easy to do wrong and many of the parameters are poorly explained. You are also limited to the shortest path between two points at a time, so these methods won’t work to generate all possible paths between multiple points unless you write code to do the analysis.

Basic Hydrologic Analysis in ArcGIS Pro Lecture:    • Basic Hydrologic Analysis in ArcGIS Pro  

Lab Exercises:
Lab 1: Calculating Areas from Raster Datasets;    • Hydrology in ArcGIS Pro, Lab Exercise 1:  ...  
Lab 2: Problems when creating Watersheds without filling the DEM;    • Hydrology in ArcGIS Pro, Lab Exercise 2:  ...  
Lab 3: Filling Sinks in a DEM;    • Hydrology in ArcGIS Pro, Lab Exercise 3:  ...  
Lab 4: Calculating an Accurate Flow Direction Raster;    • Hydrology in ArcGIS Pro, Lab Exercise 4:  ...  
Lab 5: Generating an Accurate Watershed;    • Hydrology in ArcGIS Pro, Lab Exercise 5:  ...  
Lab 6: Creating a Flow Accumulation Raster;    • Hydrology in ArcGIS Pro, Lab Exercise 6: C...  
Lab 7: Generating a Stream Network using Strahler Stream Orders;    • Hydrology in ArcGIS Pro, Lab Exercise 7:  ...  
Lab 8: Aspect Statistics within Watershed;    • Hydrology in ArcGIS Pro, Lab Exercise 8:  ...  
Lab 9: Slope Statistics within Watershed;    • Hydrology in ArcGIS Pro, Lab Exercise 9:  ...  
Lab 10: The Topographic Wetness Index (TWI);    • Hydrology in ArcGIS Pro, Lab Exercise 10: ...  
Lab 11: Finding the Shortest Path Through the Stream Network;    • Hydrology in ArcGIS Pro, Lab Exercise 11: ...  

Extra Materials:
Word Document with walk-throughs of lab exercises: https://docs.google.com/document/d/13...

Data for Lab Exercises: https://drive.google.com/file/d/1i07m...

Manuscripts discussing TWI: https://drive.google.com/file/d/1W4Ty...