Planet WGSW-24010 User Manual page 50

As it is best to survey macrophytes when the river has been at low flow for several days, the
definition of channel area is fairly easy to interpret in a consistent manner. Obviously some
degree of judgement and common sense is required to decide whether a macrophyte species is
in the channel. Macrophytes overhanging the channel but not rooted in the defined channel area
should not be counted. In general, records will be for those macrophytes which occur in the
region of the river which is rarely uncovered, and those shallow sections which have an upper
limit that may be exposed for a maximum of 50 days in any one year.
'Bank' macrophytes are those plants that occur above the limit of the river plants, and are thus
out of the water for more than 50 days in any one year, yet will be submerged or partly so, during
average flow periods.
4.4.3 Location of the sur vey length
If having completed a survey the results appear to have been affected by the physical constraints
of the survey-length location, then consideration should be given to moving the location of the
survey length within the guidance given in Box 2.
Quality assurance
If using the pacing system, each surveyor charged with determining the upstream and
downstream limits of the survey length must check, at the beginning of each survey day, the
number of their paces required to measure out the survey length. Do this for 10m as
suggested above.
The survey length should agree with the relocation features marked on the sketch map.
Decisions regarding channel definition — which specimens are 'in' and which 'out' of the
channel — are a common cause for inter-surveyor differences. Application of strict discipline
is thus required: always check whether the roots of an overhanging specimen are in the
channel or not, and do not be tempted to record specimens which are not rooted in the
channel just because they 'score'. If a species is only recorded from the waterline, mark this
on the field sheet (this will help clarify disputes between primary surveyor and auditor).
R&D Technical Report E38 36