Location: Athlone, Co. Westmeath (including townland in Roscommon) Unique ID: 260448 (from PFRA database) Initial OPW Designation APSR AFRR IRR Co-ordinates Easting: 205000 Northing: 239999 River / Catchment / Sub-catchment Type of Flooding / Flood Risk (identify all that apply) Shannon and tributaries / Shannon Fluvial non-tidal Fluvial tidal Coastal Stage 1: Desktop Review 1.1 Flood History (include review of Floodmaps.ie) River Flow Path The River Shannon runs through Athlone and flows southward towards Lough Derg. There are two main tributaries to the Shannon in Athlone. The Al River flows westerly to it s confluence with the Shannon near the weir. The Cross River flows easterly to it s confluence with the Shannon downstream of the weir. Flood Event Records Thirty flood records are listed in floodmaps.ie. The main flooding is from the River Shannon but the Al river also the cause of flooding. 1.2 Relevant information on flooding issues from OPW and LA staff PFRA database comments (in italics): OPW comments Designated APSR on the basis of predictive analysis and historical extents. Combine with Clonown and Creggan. Flooding from Shannon and Al rivers LA comments WWTW and Waterworks at risk Waterworks within 600mm Nov 09WWTW Golden Island, underwater Nov 09,- Risk of powerloss due to substations at the lock Meeting / discussion summary comments: OPW comments Athlone floods from the Shannon and has a long history of flooding River Al south east of town is also a cause of flooding to parts of Athlone. LA comments There is a planning application to the east at Creggane for a large development. This site is identified as being in the flood plain of the River Al within the PFRA. Levels in the vicinity of the site are controlled by sluice gates. Westmeath County Council suggested a range of potential flood risk management options that should be explored for Athlone, including removal of Parteen Weir and a better control of levels within Lough Derg and Lough Ree. Flood Risk Review Report UoM 25 26 Athlone V0_A 1
1.4 PFRA Data 1.4.1 PFRA hazard mapping PFRA mapping available in GIS layer: Yes No PFRA mapping included on FRR map: Yes No 1.4.2 Summary of Principal Receptors Type Primary_School Nursing_Home Hospital WTP UWWTP Arch_Local Arch_Regional Arch_National_ Monument_LV FRI score (if available) 252.5 25 250 25 25 3.1 197 25.5 42.1 1.7 Stage 1 Evaluation Total 8141.25 Aspect Clearly APSR Uncertain Flood History (1.1) OPW / LA Information (1.2) PFRA Evaluation (1.4) Overall Desktop Evaluation (if any above aspect is uncertain then overall designation is uncertain) 1.8 Proposed level of Level A Site Visit assessment for Stage 2 site visits Level B Site Visit Flood Risk Review Report UoM 25 26 Athlone V0_A 2
Stage 2: Site Inspection Level B Assessment Date and Time of Inspection Names of inspection team (including OPW/LA staff if present) Peter Smyth James Murray Date: 26/05/11 Time:18:00 2.3 Local knowledge - on-site comments (OPW, LA and any info volunteered by local residents during visit) No on-site comments. 2.4 Comments on hydraulic constrictions (bridges, etc.) and conveyance routes There are three bridge crossings within the town centre over the river Shannon; two road and one rail. The Athlone weir is at the downstream end of the town. Its span is approximately 200m. The gates controlling the levels at the weir only span 30 to 40m of this length. The ability of the sluice gates to provide any meaningful control of levels upstream of Athlone during extreme flow conditions is questionable. A large section of the Al River, on it s approach to it s confluence with the Shannon is culverted. There are several culverts upstream which could cause a constriction to flow. 2.6 Defence Assets Formal and Informal Flood Defence Assets (include effective and ineffective assets to inform asset survey and potential mitigation measures) Open Channel Watercourses Man-made river channel Flood relief channel Canal Mill leat Drainage channels / back drains Bridges and Culvert crossings Single Arch bridge Multi-Arch bridge Single Span bridge Multi-Span bridge Box culvert(s) Pipe culvert(s) Arch Culvert(s) Culverted Watercourses (culvert length is greater than just a crossing) Box culvert(s) Pipe culvert(s) Arch Culvert(s) Irregular Culvert(s) Walls and Embankments Embankment(s) Raised wall(s) Retaining wall(s) Control Structures weirs, gates, dams Fixed crest weir Adjustable weir Dam / Barrage Sluice gates Lock gates Radial gates Storage On-line storage (natural) On-line storage (artificial) Off-line storage Outfalls Flapped outfall(s) into watercourse Unflapped outfall(s) into watercourse Flood Risk Review Report UoM 25 26 Athlone V0_A 3
i.e. from smaller watercourses, drains etc. into river / estuary / sea Tidal flap(s) Tidal sluice(s) i.e. from main watercourse into estuary / sea Other Pumping Station Erosion Protection Sand Dunes Additional notes (if required): 2.8 Initial Potential Mitigation Measures Non-structural measures Structural measures Planning and Development control Sustainable Urban Drainage Systems Flood forecasting / warning Change in Operating Procedures for water level control: Public awareness campaign Individual property protection Land use management Strategic development management for floodplain development: (integration of measures into strategic development proposals) Storage: On-line Off-line Flow diversion: Flood relief channel Flood relief culvert Increase conveyance: Bridge works Channel works Floodplain Flood defences: Walls Embankments Localised works: Defence raising In-fill gaps Trash screen Maintenance works: Culvert / channel clearance Asset maintenance Relocation of properties: Improve existing defences: (describe) Other (describe): Outcomes Recommended Designation Summary Comments (if required) APSR not an APSR IRR There are two different sources of flooding within Athlone; the Shannon and the Al River. Both of these rivers have very different hydrological characteristics. Athlone has a long history of flooding. The PFRA mapping predicts an ongoing significant flood risk with this conclusion supported by both Local Authorities and the OPW. Athlone was confirmed as an APSR following a desk based assessment, with no on-site verification of this conclusion required. Flood Risk Review Report UoM 25 26 Athlone V0_A 4
Photo1: Sluices at weir in Athlone. Photo 2: Weir and sluices in Athlone Photo 3: View of Railway Bridge in Athlone Photo 4: View of Road Bridge in Athlone. Flood Risk Review Report UoM 25 26 Athlone V0_A 5
198500 199500 200000 200500 201000 201500 202000 202500 203000 203500 204000 204500 205000 205500 206000 206500 207000 207500 208000 208500 209000 209500 Athlone 244000 244500 245000 245500 246000 246500 ± 199000 243500 Legend APSR Boundary for CARs only @ @ 242500 243000 H Historic Flooding Incidents Water bodies mapped from RADARSAT-2 * Hydrometric Gauging Stations EPA River Network Roads (National Roads Authority) Airport Land OPW Embankments Historic Flood Data Architectural Heritage G _ ^ UNESCO Sites Special Protection Area Special Area for Conservation Proposed National Heritage Area National Heritage Area Benefiting Lands Rail Stations N Nursing Homes N Residential Care for the Elderly E Schools Ports and Harbours Flood Extents (PFRA, 2010) 10% AEP Flood Extent (1 in 10 chance in any given year) 1% AEP Flood Extent (1 in 100 chance in any given year) 0.1% AEP Flood Extent (1 in 1000 chance in any given year) OPW Buildings Health Centres G Garda Stations H Hospitals F Fire Stations 239000 239500 240000 240500 241000 241500 242000 R ] O H # o Rail Network Civil Defence Head Quarters Airports * Data Source - Service Régional de Traitement d Image et de Télédétection (SERTIT) (acquired on the 5th of December 2009). 238500 Client 238000 Project 237500 The PFRA Flood Extents shown are indicative. They have been developed using simple and cost-effective methods that are suitable for the PFRA. They should not be used for local decision-making or any other purpose without verification. Shannon CFRAM Study Flood Risk Review Map Title Drawing Status Job No. Athlone FINAL 32102500 Figure No. CAR 6 Scale 1:35,000 @ A3 Drawn AD/SF 0 0.5 1 2 Km Includes Ordnance Survey Ireland data reproduced under OSi Licence number EN0021011. Unauthorised reproduction infringes Ordnance Survey Ireland and Government of Ireland copyright, Ordnance Survey Ireland, 2011. Copyright reserved Jacobs UK Ltd 95 Bothwell Street, Glasgow, G2 7H Revision Jun 30, 2011 Checked Review JC KK/JM Approved IB/PS