The orientation of the canyon is determined relative to the flow of the water, not the viewer’s perspective. The sides of a canyon are named either Canyon Left or Canyon Right. You also have both Upstream and Downstream. There will be sometimes an exception to this rule where the river can flow in reverse depending on tidal flow. These types of exceptions are usually only found in canyons connected to oceans.
U Upstream – The direction from which water is flowing from.
D Downstream – The direction in which (or to which) water is flowing.
CL Canyon Left – The left side of the channel when looking downstream.
CR Canyon Right – The right side of the channel when looking downstream.
Note: It’s always important thing to remember is that “canyon left” and “canyon right” are always from the direction of flow.