Working to Protect Ontario’s Watersheds, their Natural Heritage, and our Receiving Waters
OHMapping
February 2019 — OHMapping is in stasis OHMapping was a valuable program that performed two simple functions: it colour-coded watercourses by stream order and it imposed a boundary for combined first and second-order catchments. These simple GIS outputs to aerial photographs of five watersheds enabled people to more easily trace the course of their local streams and to see some of the real outcomes of human development on the landscape, as per the map below.
We had hoped that government agencies would incorporate these simple GIS outcomes into their normal mapping routines, for which very little effort would render substantial benefits. They have not, and we need to re-evaluate if we will continue to request their increased attention or if we shall pursue or abandon more mapping ourselves.
Regardless, OHMapping led to three other outcomes we continue to deliver: Headwater Hikes; the development of a series of indicators of headwater health for inclusion in watershed report cards; and the need to identify and protect Contiguous Upland Headwater Catchments in watersheds experiencing significant development.
Excerpt from OHMapping of the Credit Watershed As OHMapping developed, we affectionately called it our “superficially meaningful tool”, as various realities popped off the maps due our simple efforts to colour-code the watercourse by stream order and to install boundaries for combined first and second-order catchments. Here is what can be seen in the map below:
1. Without any streams visible, this large agricultural area is probably in drainage tile;
2. These first (green) and second-order streams (blue) have been straightened to facilitate drainage and lack much stream-side vegetation. These watercourses offer low ecological value compared to meandering streams, while the absence of riparian plants may result in thermal loading.
3. Here we see evidence of development practices no longer acceptable – streams placed underground to facilitate development. Results include diminished natural habitat and ecological values, reduced exchanges with groundwater, and dank water flowing downstream.
