Page 100 - Freshwater-Biology-and-Ecology-Handbook

CHAPTER 2 7.6

7.6 Environmental measurements for RIVPACS

RIVPACS samples must always be accompanied by certain field measurements that are used by the predictive model, all of
which are annual averages. These parameters must be measured with every sample as they are also useful more generally for
interpretation.

Width Average of three measurements taken across different places within the sampling area
Depth Average of three measurements taken across the sampling area

Estimate of the percentage cover of different size particles, excluding bedrock:
Substrate
• Clay & silt • Sand • Gravel & pebbles • Cobbles & boulders

Table 2.4
Substrate categories used for RIVPACS

Substrate Width Description
Category (millimetres)

Clay <0.06 Sticky and cohesive
Soft in texture and not abrasive to the hands
Silt <0.06
when rubbed. Not cohesive or sticky.
Smaller than instant coffee granules and, unlike
Sand 0.06–2
silt/clay, abrasive to the hands when rubbed
Gravel 2–16 Instant coffee granule to broad bean
Pebble 16–64 Broad bean to half fist size

Cobbles 64–256 Half fist to head size
Boulders >256 Head size and larger

100 | Freshwater Biology and Ecology Handbook
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