Geographic Information Systems
Bloomsburg, PA 17815
Maps By Mitch
June 11, 2012
Welcome to "Maps By Mitch". A "blog" of sorts to highlight various maps and the techniques used to create them. I hope to have a new "map" posted on a monthly basis.
This month’s map comes from a gentleman who approached me last month and asked a very intriguing question: what would the Pennsylvania counties look like if they were to be based on watersheds rather than demographics? Presently, this question was prompted by the difficulty to manage water resource projects in Pennsylvania. This is because a single watershed may span multiple counties. After some discussion with the gentleman, I decided to take this idea and create a correlating map.
First a little background on PA watersheds. Pennsylvania is comprised of six main watersheds with a Hydrologic Unit Code (HUC) 4. They are: Delaware, Erie, Genessee, Ohio, Potomac and Susquehanna. As HUC numbers increase, the size of the watershed decreases. For instance, a HUC 6 watershed contains fewer square miles than a HUC 4 watershed. The data used for the maps contains HUC 4 and HUC 10 watersheds.
The map at the top of the page shows PA’s HUC 4 watersheds, shades of blue, with the current county boundaries. The lower map shows a rendition of what the counties may look like if based on HUC 10 Watersheds. This map was created by merging HUC 10 watersheds together in order to encompass a major river and its tributaries. Therefore, no tributary from one HUC 10 (county) enters any other county.
This map was created using data collected from the Pennsylvania Spatial Data Access (PASDA) website and I wish to thank Eric Jespersen from Fisher Associates for his insight and help with this project.
Click on the map for a PDF (3.7 MB).