My book "Thousands are Sailing: a brief song history of Irish emigration" contains 20 songs, each one supported by a contemporary prose account illustrating the same aspect, some commentary and pictures. It contains "Paddy on the canal" but as said above it has no specific location.I know of no song which has a location on the Welland Canal - have you looked in Edith Fowke's works or at her unpublished collection which is (I believe) at York University in Toronto?