[OSM-talk] Large Rivers in general, mapnik rendering in Particular

[David Earl]

You could do it as a relation.

The river bank would be a set of ways (each of which shares its end 
nodes with the ends of one of the others), and you could have a role for 
the one or two ways which close the loop which says "this is structural, 
not really part of the river bank". The renderer would have to assemble 
the polygon from the constituent ways (start with one way, find the end 
node as the start node of another way and so on), but then rendering 
would be as per any other polygon.

It's a bit fiddly, but it removes the problems of the
artificial connections across the water not eing idetifiable while at 
the same time still providing a complete polygon (albeit indirectly) for 
the renderer to work on.

David