2023 Track 1 Day 2: Cowan


Sewershed and Overland Flow Route Delineation with ArcHYDRO


Like many municipalities in Ontario, the Town of Caledon is required to apply for consolidated linear infrastructure (CLI) environmental compliance approval (ECA) for their Municipal Stormwater Management System. The Town of Caledon commissioned the Sustainable Technologies Evaluation Program (STEP) to complete a stormwater drainage study for overall 24 settlement areas within the Municipality.

This presentation provides details on how one (1)-meter resolution Light Detection and Ranging (LiDAR) data was used in conjunction with ArcHYDRO (i.e. tools of ArcGIS) to delineate sewersheds and overland flow routes during frequent storm events – termed as “minor flow” for storms with 2 to 10 year return periods – and infrequent storm events – termed as “major flow” for storms with a return period of ten years or greater.

In addition to LiDAR and ArcHYDRO, sewer shapefiles and other geospatial data from the Town of Caledon was used to delineate these minor system flow patterns.

Ultimately, the methodology employed allowed the minor and major flow systems to be delineated successfully for each of the settlement areas. The results of this study also helped to identify points of interest in the Town of Caledon’s drainage where additional investigation may be needed.

Beyond supporting the CLI ECA process, this study will pave the way for identifying maintenance considerations and green infrastructure retrofit opportunities for the Town of Caledon’s stormwater infrastructure.


James Cowan

James Cowan, Credit Valley Conservation (CVC)

James Cowan is a coordinator with the Integrated Water Management team at Credit Valley Conservation (CVC). James is a recent graduate of the University of Guelph’s Environmental Engineering program, and his current role is to support green infrastructure and low-impact development projects at CVC.