Terrain Analysis

Terrain Analysis in ArcGIS Pro

Kendrick Wittmer

Date: 5/7/2025 

    This assignment involved a series of terrain analysis tasks using elevation data for the Driftless Area in southeastern Minnesota. The lab focused on visibility analysis, elevation profiling, and watershed delineation using ArcGIS Pro’s 3D and spatial analyst tools. The work was divided into two main projects, each producing a map layout and providing practical experience with real-world elevation modeling techniques.

Visibility and Elevation Profiles

In this section, I worked with a 3-meter resolution LiDAR-derived DEM to examine line-of-sight visibility and vertical terrain profiles.

• Viewshed Analysis: Using the Geodesic Viewshed tool, I identified all areas visible from a specific observer point. The resulting map highlights visible zones in orange, simulating real-world line-of-sight visibility for activities like lookout tower placement or scenic analysis.

• Sightline Tool: I ran a Line of Sight analysis along a line feature to determine which parts of the path were visible or obscured. The output showed visible (green) and hidden (red) sections of the line, clearly illustrating how terrain blocks sightlines.

• Elevation Profile: I applied the Interpolate Shape tool on a local road network to extract elevation values along a path. This was used to generate a road profile chart, which visualizes elevation changes over distance.

  
  
  

Final Deliverable:

    The final map includes the hillshaded terrain, viewshed zones, sightline results, and a clean elevation profile graph. Together, these outputs help visualize how terrain affects visibility and movement in rugged landscapes like the Driftless Region.

Project 2: Watershed Delineation

    The second portion of the lab focused on hydrological modeling using the same DEM to derive a watershed around Brush Valley Creek.

Key Tasks:

• Fill Tool: Corrected small depressions in the DEM that could obstruct water flow modeling.

• Flow Direction and Accumulation: Modeled how water would flow downhill across the terrain and accumulated flow across cells.

• Stream Thresholding: Applied a 50,000-cell threshold to isolate likely stream channels, then reclassified and converted them into vector format for clarity.

• Outlet Point & Snap Pour Point: Digitized an outlet point for the main stream and snapped it to the nearest high-flow cell to define the watershed boundary.

• Watershed Tool: Used the snapped pour point to generate the final watershed raster and converted it into a vector polygon for map presentation.

Final Deliverable:

    The map shows the Brush Valley Creek watershed shaded in green, with streams delineated in blue, and the outlet point marked in red. 

Takeaways

    This lab demonstrated the versatility of elevation data in environmental analysis. From modeling what can be seen to understanding how water flows, terrain analysis in ArcGIS Pro offers essential tools for planning, conservation, and geospatial analysis. The ability to combine raster and vector workflows also highlighted the power of GIS in tackling diverse geographic questions.