Vegetation (Floating River Vegetation) - Office of Public Works

4.3 River corridor water dynamics
A feature associated with Water Courses of Plain to Montane Levels with Aquatic
vegetation (Floating River Vegetation) EU Code 3260 are watercourses with lower water levels
during summer months and increased water levels in winter (EUNIS website). Plant identification
keys show that watercourses supporting floating river vegetation have specific river flow, water
depth and water quality. The characteristics of each watercourse therefore can influence aquatic
species diversity.
Information on the flow rate of the main channels surveyed for floating river vegetation was
compiled from the Office of Public Work hydrometric data available (OPW website). Three flow
rates were selected for comparison, namely 1% corresponding to the flow in cubic metre per second
(m 3 /s) exceeded only 1% of the time 3 - 4 days per year on average, 50% an approximate average
flow and 99% the flow exceeded only 1% of the time in cubic metre per second (m 3 /s). Also
detailed are the summer months when flow was at its lowest and most constant from the graphed
information over a number of recent years.
River Name 1%
m 3 /s
Owenriff
(Oughterard)
Clare River
(Corrofin)
River Corrib (Galway)
River Suir
(Clonmel)
River Nore
(John's Bridge)
Mulkear River
(Annacotty)
Maigue
(Castleroberts)
River Feale (Listowel)
Bandon River
50%
m 3 /s
99%
m 3 /s
No flow rate data available
Low and even flow rates during summer period
(Months)
72.0 10.7 0.97 (2003) April – Mid May, Mid June-Mid July
No flow rate data available
184 33.2 3.60 (2005) Insufficient data
112 17.6 2.47 (1999) Mid June – Mid September
(2000) Mid May – Mid September
83.9 10.4 1.53 (2005) May - September
70.2 7.46 0.7 (2005) May - September
162 9.43 0.81 (2004) Mid May – June
(2005) Mid June – Mid July
79.8 9.44 0.84 (2004) May – September
(Carranure)
(2005) June, Mid July, Mid August - September
Table 15 Flow rates of main channels surveyed for floating river vegetation.
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