Channel dimensions, influences and special features

Page 4 of the form contains Section L – channel dimensions. These are measured at one location within the 500m. Ideally, that location should be in a straight or uniform reach (i.e. not on a sharp bend), with clearly defined banks and preferably across a riffle. If riffles are not present in the site, a uniform location with clearly defined banks should be used. Channel dimensions do not have to be measured at a spot-check.


Guidance on how to measure the channel is included in the spot-check key. Where it is safe to do so, the bankfull width, wetted water width and water depth should be recorded, preferably using the ranging pole. A rangefinder will be needed for estimating the width of larger rivers, and these instruments should be calibrated regularly.


Page 4 also establishes the absence, presence (✓) or extensive occurrence (E) of the following: 

  • ‘features of special interest’ (Section M); 
  • ‘notable nuisance plants’ (Section O); 
  • alders, including diseased trees (Section Q). 


Features marked by an *asterisk (e.g. *leafy debris) can be recorded as ‘present’ even if they do not occupy at least 1% of the site.


Section N requires surveyors to record whether or not the channel is choked with vegetation. This is important since RHS might be carried out at times when plant growth in rivers is at its greatest.


Section P contains text prompts to assist surveyors in describing the overall characteristics of the site, as well as providing a space for noting other relevant observations. Additional relevant observations are encouraged and these should be included on a separate sheet, provided that the mid-site grid reference is clearly marked on it.


Section R contains seven cross-check prompts to ensure that all parts of the survey form have been completed correctly.