A botanical survey of Scotland

Gauged river runoff records extend only over limited timespans, mostly commencing post‐1940. Historical sources can provide additional material to assist in extending the hydrological record into the nineteenth century and earlier. Such sources vary, however, in the nature of the detail, in their reliability and in their potential use in hydrological reconstruction. This paper outlines the main categories of sources available, subdivided into those which have been authenticated and those of variable reliability.