merge with river_poly layer as needed. These seem to overlap.

river rapids
? waterway=rapids is only listed for nodes and polylines, not areas
RP: we can use it for either, don't worry about what it says on the wiki; that's only a guide
the same naming problem as for rapids_cl exists here also
HB Aug 2012: for name we can use whitewater:section_name from the osm Whitewater_sports wiki page. We don't know the grade, so just putting whitewater=rapids. With that, looks ok to me now.
for the record: a review of the vector layers shows that rapid_cl and rapid_poly do not overlap in the source data, although sometime they adjoin when one expands into the other.
Further ML discussion:
and ?