Last Friday I managed to get a picture from the air that captures all of Ottawa's main rivers. Although there are three of them, Ottawa is not to be confused with Trois Rivières just west of Quebec, a town whose citizens are known as Trifluviens, the rivers in their neighbourhood being the St. Laurent, the St. Maurice and the Bécancour.
Here are the Rideau, the Gatineau and the Ottawa:
It's striking to see how close is the Rideau-Ottawa confluence to the Gatineau-Ottawa confluence. Interestingly enough the sources of the Gatineau and the Ottawa Rivers are also fairly close together (in the lake system north of the Baskatong reservoir), although they meander for hundreds of kilometres in different directions beyond that point.