During River Habitat Surveys on the physical structure of the watercourses
in the U.K., channel vegetation types were recorded as present or extensive
in 10 m wide belt transects at 50 m intervals over 500 m reaches for some
2435 stratified random sites in 1995-96. Data on attached, submerged, emerg
ent and free-floating aquatic vegetation were grouped into nine broad morph
ological groups such as submerged broad-, linear- and fine-leaved, free-flo
ating, emergent, etc. Vegetation data are supported by assessments of physi
cal parameters at each site including dimension, flow types, channel substr
ate and the slope of the channel. The general habitat requirements for each
group are shown to agree with assumed requirements but with a broader dist
ribution of habitats. Eight percent of channels had excessive growths of ve
getation and would normally be considered for weed control; this was a mini
mum estimate.