Information from River-Corridor surveys

A river-corridor survey (RCS), routinely undertaken on behalf of the National Rivers Authority (NRA), provides a consistent national approach to gathering and recording environmental information on 500-m stretches of river corridor. The development of RCS is reviewed and the methodology which is currently applied within the NRA is described. A research programme, sponsored by the NRA, to develop scientifically-valid methods for extracting quantitative information from RCS maps is outlined. The methodology allows for spatial distortions and operator variance in mapping the 500-m stretches. It is based on an abundance scale and therefore provides data which can be quantitatively combined and analysed (a) to highlight different properties of the river corridor and (b) to summarize those properties over different corridor lengths. The results of an example application of these methods of information extraction to a 14.5-km length of river corridor are presented.