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The survey area and sampling area
The sampling site should be in a survey area with consistent features to ensure that a minor error in
re-locating a site does not upset the monitoring result. This also helps to ensure that the site is not
in an isolated habitat.
The survey area must be seven channel widths, up to a maximum of 50 metres, either side of
the sampling area (Figure 2.3). This reduces differences between samples taken on different
occasions that may not be in the exact location sampled previously. Surveys that need more
intensive sampling, for conservation or those which require replicate samples, can also use this
larger area.
Survey area
Sampling area
7 widths 7 widths
Survey area
Sampling area
50 metres 50 metres
Figure 2.3
The sampling area should be centred in a survey area with the same characteristics
and extending 7-widths (in a narrow stream) or up to 50 metres (in a wider stream)
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