Vegetation (Floating River Vegetation) - Office of Public Works

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With the exception of the Owenriff River and the River Corrib where no flow rate data was available, all the other rivers showed elevated flow rates in winter time which were substantially reduced in summer months. The only rivers not to possess a period of low flow without significant floods lasting more than a month during the summer were the River Feale and the Clare River. A period of consistently low flow rate was evident for all other main channels from May to July or May to September. Similarly to flow rate, data for water levels for the main channels surveyed data was also collated from the Office of Public Work hydrometric data. Three levels were selected for comparison, namely 1% corresponding to a very high water level, recorded in metres above ordnance survey datum, 50% an approximate average water level and 99% a very low water level, recorded in metres above ordnance survey datum. The Poolbeg datum is used by OPW, mean sea level is about 2.7m. Also detailed is the summer months when water level was at its lowest and most constant from the graphed information. River Name Owenriff (Oughterard) Clare River (Corrofin) River Corrib (Galway) River Suir (Clonmel) Nore (John's Bridge) Mulkear River (Annacotty) Maigue (Castleroberts) River Feale (Listowel) Bandon River 1% mAOD 50% mAOD 99% mAOD 10.86 10.43 10.30 (2003) erratic Description of water level during summer months 27.91 25.97 25.17 (2003) April – Mid May, Mid June-Mid July No data available 19.2 7 17.50 16.83 (2005) Mid June-July, August - September 45.7 44.8 44.6 (1999) Mid June – September 12.7 9 10.7 2 18.1 2 (2000) Mid May – August (2001) Mid May – Mid August 10.87 10.57 (2004) Mid May – Mid August (2005) May-July 9.81 9.03 (2005) June - September 17.03 16.75 (2003) erratic (2004) Mid May – Mid June (2005) Mid June - July 8.28 7.42 7.04 (2004) May – Mid June (Carranure) (2005) Mid June – Mid July. Table 16 Water levels of main channels surveyed for floating river vegetation. mAOD – metres above ordnance datum 36
Not shown in the above data set is the effect of weirs on water levels, which may be estimated based on the hydrometric point data and the consistent water level throughout the year. For floating river vegetation the above data illustrates that a rise and fall in water levels occurs on the main channels surveyed. A direct comparison cannot be made between changes in water levels during summer and winter months, which are characteristic of Habitat EU 3260, as weirs are influential in regulating the water levels of some watercourses, colonised by aquatic vegetation. It is apparent that other factors are more important for determining floating river vegetation. Water quality of the main channels (Table 17) and a selection of tributary rivers (Table 18) surveyed for floating river vegetation was compiled from the EPA river water quality map noting the location of the EPA sample site, the water quality status and the year in which the sampling took place. Where possible a selection of sites was chosen for each river. River Name Owenriff River Clare River River Corrib Bridge upstream Lough Corrib 1km upstream Oughterard Bridge 1km downstream Lough Affard Corrofin Bridge Bridge South of Turloughmore Clare Galway Bridge Location Pollution Rating Year Unpolluted Unpolluted Unpolluted Moderately Polluted Unpolluted Slightly polluted 2002 2002 2002 2003 2003 2003 Salmon Weir Bridge Galway Unpolluted 2000 River Suir Marlfield upstream Clonmel River Nore Mulkear River River Maigue River Feale Kilsheeelin Bridge & 1.5km upstream Carrick 1 km upstream Green's Bridge Fennessy's Mill (Ossory Bridge) North East of Warrington Annacotty Bridge & 2km downstream station Ford downstream of Killeengarriff River Howardstown Bridge Bridge in Croom & Castleroberts Bridge 2km Downstream Listowel RHS Listowel Bridge Finuge Bridge Unpolluted Moderately polluted Unpolluted Slightly polluted Slightly polluted Unpolluted Unpolluted Slightly polluted Moderately polluted Unpolluted Unpolluted Moderately Polluted Bandon Bridge 3km South East of Dunmanway & Manch Bridge Slightly polluted 2003 River Bridge upstream Bandon River Unpolluted 2003 Table 17 Water quality of main channels. Rivers with floating river vegetation highlighted (yellow). 37 2005 2005 2004 2004 2004 2002 2002 2002 2002 2005 2005 2005
Page 1 and 2: ISSN 1649 - 9840 SERIES OF ECOLOGIC
Page 3 and 4: Foreword This Ecological Impact Ass
Page 5 and 6: Executive Summary Table of Contents
Page 7 and 8: 1.0 Introduction This study was com
Page 9 and 10: and fauna. The OPW has a multi-annu
Page 11 and 12: Currently twenty-one Special Areas
Page 13 and 14: 2.1.4 Lower River Shannon Special A
Page 15 and 16: 2.2.4 Site elevations within the Lo
Page 17 and 18: 2.3.4 Site integrity of the Lower R
Page 19 and 20: 3.0 Ecological Assessment of Water
Page 21 and 22: 3.2 Distribution and extent of floa
Page 23 and 24: 3.2.1 Floating river vegetation of
Page 25 and 26: aquatic moss. 3.2.3 Floating river
Page 27 and 28: 3.2.5 Floating river vegetation wit
Page 29 and 30: Starwort, Callitriche species •Ro
Page 31 and 32: Each form of reproduction requires
Page 33 and 34: prevented aquatic growth. Water lev
Page 35 and 36: G.densa was the dominant floating r
Page 37 and 38: 4.0 Description of maintenance oper
Page 39 and 40: consultation with the Foreman / Tec
Page 41: 4.3 River corridor water dynamics A
Page 45 and 46: 4.4 Physical, chemical and biologic
Page 47 and 48: •Survey watercourses to determine
Page 49 and 50: The primary riverbed substrate of w
Page 51 and 52: gravel require loosening assess the
Page 53 and 54: • Livestock should be restricted
Page 55 and 56: River Breagagh Winter 2006 River Br
Page 57 and 58: River Breagagh Winter 2006 Ranuncli
Page 59 and 60: 6.0 Conclusion and summary •Arter
Page 61 and 62: References •Blamey, M., Fritter,
Page 63 and 64: Appendix A - Special Areas of Conse
Page 65 and 66: Lower River Shannon Special Areas o
Page 67 and 68: Channel name Location coordinates E
Page 69 and 70: Appendix C - Habitat classification
Page 71 and 72: Lower River Shannon Special Area of
Page 73 and 74: Lough Corrib Special Area of Conser
Page 75 and 76: 7 Lower River Suir Special Area of
Page 77 and 78: C1 Lower River Shannon Special Area
Page 79 and 80: 6 C1/12/2 C1/18/1/1 /14/7/3 C/20/1
Page 81 and 82: Appendix E - Physical parameters re
Page 83 and 84: River Barrow and River Nore Special
Page 85 and 86: Latin Name English Name Appendix F
Page 87 and 88: Latin Name English Name Potamogeton

Vegetation (Floating River Vegetation) - Office of Public Works

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