Data interpretation
On the river level data pages, the graphs show the change in
river level over the last two to three days. An increase in river
level is normally associated with rainfall in the catchment.
However, certain sites are subject to artificial control by, for
instance, hydro power stations that may artificially influence the
level of the river (see the Glass at Kerrow Wood as an example).
SEPA uses river level data to calculate the river flow since the
direct measurement of flow is difficult and expensive.
The graphs show the river level relative to a local datum and may
not directly represent the depth of water. To give the user some
perspective of the relative level of the river, a 'base level' has
been given for each site. The base level represents a typical
summer level in the river and has been calculated as the level that
is exceeded for 95% of the time. The level will be below this for
approximately 18 days in an average year. At some sites this figure
is not available.