INFORMATION FROM RIVER-CORRIDOR SURVEYS

A river-corridor survey (RCS), routinely undertaken on behalf of the N ational Rivers Authority (NRA), provides a consistent national approac h to gathering and recording environmental information on 500-m stretc hes of river corridor. The development of RCS is reviewed and the meth odology which is currently applied within the NRA is described. A rese arch programme, sponsored by the NRA, to develop scientifically-valid methods for extracting quantitative information from RCS maps is outli ned. The methodology allows for spatial distortions and operator varia nce in mapping the 500-m stretches. It is based on an abundance scale and therefore provides data which can be quantitatively combined and a nalysed (a) to highlight different properties of the river corridor an d (b) to summarize those properties over different corridor lengths. T he results of an example application of these methods of information e xtraction to a 14.5-km length of river corridor are presented.