The Aire and Calder catchment ranges from the heights of the Pennines and Yorkshire Dales to low-lying floodplains. Bradford, Leeds, Huddersfield, Skipton and Halifax are part of the highly urbanised areas where much of the former industrial land alongside the rivers is the focus for regeneration. In excess of 2.2 million people live in the catchment. There is an extensive canal network in the catchment, including the Leeds Liverpool Canal which is the longest in Britain.