4 HYDRAULIC MODEL DETAILS

4.1 CARRICK-ON-SUIR

4.1.1 Introduction

Model 7 comprises four of the AFAs under the Suir CFRAM Study; these are Carrick-on-Suir, Piltown, Portlaw and Clodiagh. Model 7 is subject to both fluvial and tidal flood risk. It encompasses a 33km stretch of the River Suir, as well as nine associated tributaries and one canal reach.

The Carrick-On-Suir AFA is affected by the River Suir (at the upstream extent of the model) and its tributaries the Glen River, Lingaun River and the Suir Trib 1. The Piltown AFA is affected by a tributary of the Suir River, the Pil River. The Fiddown AFA is affected by the Suir River. The Portlaw AFA is affected by a tributary of the Suir River, the Clodiagh River, two small tributary of the Clodiagh and a short stretch of canal.

The Suir catchment catchment is predominantly rural. The majority of the Suir catchment drainage enters Model 7 at the Suir River upstream of Carrick-on-Suir AFA. The tributaries of the Suir River that drain that largest areas are the Clodiagh River draining an area of 130km2, the Pil River draining an area of 85km2 and the Glen River draining an area of almost 44km2.

There are two gauging stations located along the length of the Model:

 Fiddown (16061) has continuous tide data from 1968 to 2005 which is considered to be of good quality and therefore can be used for verification of the hydrometric model for this reach of the Suir.  Carrick-on-Suir (16062) has continuous tide data from 1972 to 2005. For the purpose of the CFRAM study, the tide data for this gauge is to be used as part of the development for the hydraulic model.

A number of watercourse have been identified as HPW in Model 7. Stretches of the Suir River, Glen River and Ligaun River are identified as HPW as they pass through the Carrick-on-Suir AFA. These reaches have been modelled as 1D-2D using the MIKE suite software. A short stretch of the Pil River has been identified as HPW as it passes through the Piltown AFA. A stretch of the Clodiagh River and canal are identified as HPW as they pass through the Portlaw AFA. All of these reaches and the associated designated MPW reaches have been modelled as 1D using MIKE.

4.1.2 Hydraulic Model Schematisation

The maps below illustrate the extent of the modelled catchment, river centre line, HEP locations and AFA extents as applicable. Model 7 contains 9 Upstream Limit HEPs, 1 Downstream Limit HEP, 2 Gauging Station HEPs, 10 Intermediate HEPs and 16 Tributary HEPS. Due to the quantity of tributary HEPS, the intermediate HEPs are not shown.

The maps below illustrate the modelled extents and general topography of the catchment.

4.1.3 Hydraulic Model Construction

4.1.3.1 Critical Structures Photographs of the structures are not available. As such the cross-section of the structure is shown below for reference.

2775 (Creamery Rd., Piltown AFA) - Restricts flow in the River Pil

2860 (Main St., Piltown AFA) – Restricts flow in the River Pil

697J (Sir Johns Rd., Carrick-on-Suir AFA) – Restricts flow in the Glen River (4612 chainage)

662J (Railway Bridge, Carrick-on-Suir AFA) – Restricts flow in the Glen River (4650 chainage)

418J (Orchard Crescent, Carrick-on-Suir AFA) – Restricts flow in the Glen River (4888 chainage).

218J (Clonmel Rd., Carrick-on-Suir AFA) – Restricts flow in the Glen River

4.1.3.2 Defences Type Watercourse Bank Model Start Model End Modelled Chainage Chainage Standard of (approx.) (approx.) Protection (AEP)

1 WALL GLEN/GLEN LEFT GLEN TRIB GLEN 4974 2% AEP TRIB 231

2 EMBANKMENT GLEN LEFT 4974 5080 2% AEP

3 EMBANKMENT GLEN RIGHT 4884 5020 2% AEP 4 WALL GLEN RIGHT 5020 5080 2% AEP

5 WALL GLEN LEFT 5094 5244 2% AEP

6 WALL GLEN RIGHT 5094 5244 2% AEP

7 EMBANKMENT SUIR LEFT 9215 9408 2% AEP

8 WALL SUIR LEFT 9408 9769 2% AEP

9 EMBANKMENT SUIR RIGHT 9446 9515 2% AEP

10 WALL SUIR RIGHT 9515 9769 2% AEP

11 WALL SUIR LEFT 9787 10058 2% AEP

12 WALL SUIR LEFT 10078 10280 2% AEP

13 EMBANKMENT SUIR LEFT 10280 10496 2% AEP

14 WALL GLEN TRIB 1 LEFT 158 210 2% AEP

Informal

15 WALL SUIR LEFT 17443 17545 0.1% AEP The figure below shows the locations of the flood defences in Carrick-on-Suir:

14 3 1 4

6 2

5 7 8

13 11 9 12 10

There are 14 formal defences (6 walls and 8 embankments) in the Carrick-on-Suir AFA. The main defences are located along the right and left banks of the Suir River, with seven located along the left and right banks of the Glen River. All defences have been represented using the survey crest heights. All of the flood defences in Carrick-on-Suir are designed to defend up to a 1 in 50 year event (2% AEP).

There are no formal flood defences in the Piltown or Portlaw AFAs. There is a short stretch of flood wall in the Fiddown AFA (shown above).

4.1.3.3 Information on Other Structures No survey data was available for a culvert at the downstream end of the Glen River at 1556 chainage, this was estimated from a site visit and using aerial mapping.

On the River Suir in Fiddown AFA the bridge is too large to be hydraulically significant. As such it was not included in the model. However, to ensure the affect of the bridge piers was accounted for in the model the resistance was locally increased. In addition to this, the data on the southern limb (right) of the Suir River here was estimated as no data was available.

In Fiddown AFA the watercourse splits into two. No data was available for the bridge on the southern limb (right) the Suir River (chainage 17453). The data on the southern limb (right) of the Suir River here was estimated using aerial imaging as no data was available (see below).

4.1.3.4 Data Review & Quality Survey data for this model was surveyed in 1960s in the MPWs and 2007 in the HPW reaches. The original survey data was not available and so verification of this data has not been possible. The downstream reach (1.5km) of the Piltown River survey data was not available, including the dimensions of the railway bridge crossing. Cross-sections were interpolated along this reach.

In Carrick-on-Suir AFA there were no levels available for the flood wall at the downstream end of the Glen River. This level was taken from the parapet of the bridge which is considered an acceptable approach; see photo below. Floodwall

Culvert Parapet

The bathymetry has been adjusted to account for the deck levels of roads and bridges.

4.1.3.5 Model Boundaries Full details of the flow estimates are provided in the Suir CFRAM Hydrology Report. The boundary conditions implemented in the model are shown below.

A number of inflow hydrographs are used as the upstream boundaries of the model. No adjustments have been made to the hydrological inputs. The below figure below provides an example of the associated upstream hydrograph generated for the 0.1% AEP return period in the Suir River.

The downstream boundary condition is a tide hydrograph. Outputs from the Irish Coastal Protection Strategy Study (ICPSS) have resulted in extreme tidal and storm surge water levels being made available around the Irish Coast for a range of Annual Exceedance Probabilities (AEPs). The locations of the ICPSS nodes along with the relevant AFA locations are shown in the figure below. The associated AEP water levels for each of the nodes are contained in the table following the location diagram.

The coastal boundary for this model is set across Waterford Harbour. The closest ICPSS point to the boundary is W_5. This was used to provide the extreme water level information.

ICPSS AEP (%) Node 50 20 10 5 2 1 0.5 0.1

Highest Total Water Level to OD Malin (m)

W_5 2.33 2.42 2.49 2.55 2.63 2.69 2.76 2.9

A representative tidal profile for Waterford Harbour was generated based on Admiralty Tide Table data for Dunmore East.

A normalised 48 hour surge profile was scaled based on the difference between the peak water level of the generated tidal profile and the target extreme water level from the table above. The scaled surge profile was then appended to the tidal profile to achieve a representative combined tidal and storm surge profile for the required AEP events. The figure below illustrates the tidal profile, storm surge profile and resultant combined water level profile. The water level profile was applied as a dynamic water level boundary at the downstream extent of the Suir River in Model 7 (chainage 32750). The figure below provides an example of the associated downstream tide hydrograph in the Suir River.

4.1.3.6 Model Roughness

Canal - CLOM_0720W Canal - CLOM_1093W

Manning’s n = 0.060 Manning’s n = 0.040

Clean winding, some weeds and stones, medium to Clean winding, gravel bottom, light brush on banks dense brush in winter Pil Trib – 744 Clodiagh River – 19CLOD004608

Manning’s n = 0.035 Manning’s n = 0.040

Clean fairly straight with stones and weeds, Clean, winding, with some pools and shoals floodplain has short grass

Clodiagh River – 19CLOD002333 Clodiagh Trib 1 – 16CLO10002363

Manning’s n = 0.040 Manning’s n = 0.0400

Clean, winding some pools and shoal, floodplain Straight, lower stages, ineffective slopes and has light brush and trees in summer sections, floodplain has short grass

Clodiagh Trib 1 – 16CL3000110 Clodiagh Trib 2 – 19CL2000387

Manning’s n = 0.040 Manning’s n = 0.040

Clean straight, lower stages more ineffective slopes Clean winding, some pools and shoals, floodplain and sections has light brush and trees in summer

Glen River – 719 Glen River – 3101

Manning’s n = 0.035 Manning’s = 0.035

Clean, straight, full stage, no rifts or deep pools, Clean, winding, some pools and shoals, with some some stones and weeds weeds and stones

Glen Trib 1 – 119A Linguan River – 1796

Manning’s n = 0.035 Manning’s n = 0.040

Clean, straight, some pools and shoals, some Clean winding, lower stages, more ineffective stones and weeds slopes and sections, some pools and shoals

Linguan River – 466 Pil River – 1010

Manning’s n = 0.040 channel, 0.07 banks Manning’s n = 0.035 channel

Channel; Winding, some pools and shoals, lower Channel; Clean, winding no rifts or deep pools stages, more ineffective slopes and sections

Banks; Medium to dense brush in summer

Pil River – 2161 River Suir Trib 1 – 1013

Manning’s n = 0.035 Manning’s n = 0.035

Clean, winding, with some weeds and stones Clean, straight, no rifts or deep pools, but some stones and weeds

Suir Trib 1 – 559 Suir River – 42065

Manning’s n = 0.035 Manning’s n = 0.030 Clean, winding, some stones and weeds, some Clean, straight, full stage, no rifts or deep pool pools and shoals

Manning’s n = 0.025

Clean, straight, full stage, no rifts or deep pools

4.1.4 Hydraulic Model Calibration, Verification and Performance

4.1.4.1 Key Historical Floods (a) Recurring. Minutes of a meeting with the Portlaw Area Engineer and Waterford County council, dated 20/02/2006, states that a low point on the R680 regional road floods on a regular basis at Toberagattabrack.

Toberagattabrack is located approximately 1km west of Carrick-on-Suir. The flood extent does not reach Toberagattabrack during all simulated return periods (10%, 1 % and 0.1%), suggesting that this flood event is not fluvial/tidal and is possibly pluvial.

Toberagattabrack

(b) Feb 2014. An article found on the www.nationalist.ie recalls a flood event occurring at Clonmel, upstream of Carrick-on suir. The flood extent was limited to the Quay area in Clonmel due to the installed flood defences, no properties or major amenities were affected. The article suggests that during flooding of this extent at Clonmel, fluvial flooding would have usually occurred at Carrick-on-Suir. No flooding occurred at Carrick-on-Suir during this event since the flood defences at in Carrick-on-Suir have been completed.

In 2003 the Carrick-on-Suir Flood Alleviation Scheme was completed, resulting in the construction of 14 walls and embankments along the Suir River and its Tributary the Glen River which defend up to the 50 year return period flood or 2% AEP event. The figure below shows the water level in the River Suir does not over top the embankments during a 1% AEP fluvial event.

Peak water level at Suir River 9425 chainage during 1% AEP Fluvial event

Below shows the flood extent in Carrick-on-Suir during the 10% AEP and 1% AEP events. No flooding occurs in the Carrick-on-Suir AFA which shows the defences are functional during the 10% AEP. Flooding occurs in Carrick-on-Suir during the 1% AEP event, this is due to the Glen River overtopping its banks.

10% AEP Fluvial event

1% AEP Fluvial event (c) Nov 2009. A review of the historic data found in the OPW 2011 Suir Catchment Flood Risk Assessment and Management Study, Hydrology Report describes flood defence walls constructed along the Suir and its tributary the Glen River in 2003. A flood extent map of the 2009 flood is included in the report (see below), showing the effect of the walls on retaining flood flows. The 10% AEP fluvial modelled extent is shown below. This suggests the November 2009 event was around a 10% AEP fluvial event.

(d) February Minutes to a meeting with the Portlaw Area Engineer and Waterford County 2006 Council, dated 20/02/2006, states a breach in a flood protection embankment of the River Suir results in several hundred acres of Farmland on the Suir Floodplain being inundated with floodwaters during every high tide event. Water levels during the 10% AEP tidal event are 3mOD where the Clodiagh River joins the Suir River, a cross-section through the Suir is shown below. The channel cross-sections were taken from NDHM data which has not picked up any flood defences. This shows that flooding occurs here during the 10% AEP tidal event.

(e) Oct 2004. Minutes of a meeting with the Newarth (Kilkenny County Council) Area Engineer for flooding indicate that flooding occurred in Piltown in Oct 2004, at Main Street and Creamery Road. These are recurring events, which affect commercial properties, residential properties and agricultural land. Review of the historic data found on www.floodmaps.ie indicated flooding occurred at Portlaw as a result of high water levels in the Suir, resulting in high water levels in the Clodiagh. Some residential properties in Portlaw were flooded, no further information on levels or flood extent is available for this event so it cannot be used for calibration.

The modelled flood extents during a range of return periods (10% 1% and 0.1% AEP) show that flooding occurs on Main Street and Creamery Road due to incapacity of the Clodiagh channel. Flooding occurs during the 10% AEP return period with flood depths of approximately 0.6m, affecting three residential properties. The figure below shows the maximum flood extent during the 10% AEP return period at Main Street and Creamery Road, Piltown.

Creamery Road Main Street

10% AEP fluvial event (f) Nov 2002 A review of the historic data found on www.floodmaps.ie included a list of areas that flood and require flood alleviation works. During November 2002 Piltown Village was flooded at Old Main Street (N24 Rd.) and Creamery Rd. Flooding was attributed to high tides, south-easterly winds and heavy rainfall. Roads affected were impassable, 8 residential properties and 4 commercial properties were affected. The flooding is ranked by two levels, level 1; six times a year and level 2; four times a year. Level 1 flooding only affects farmland and rear gardens. No extents or levels are available for this event, thus it should only be used for verification of the modelled results.

The modelled flood extents during all return periods (10% 1% and 0.1% AEP) show that flooding occurs on Main Street and Creamery Road. Flooding occurs during the 10% AEP return period with flood depths of between 0.6-1.2m approx, affecting three residential properties. This event helps verify the model to recurring flood event in Portlaw as flooding will occur here during a much lower event than the 10% AEP return period. The figure above shows the maximum flood extent during the 10% AEP return period at Main Street and Creamery Road, Piltown.

(g) Nov 2000. Review of the historic data found on www.floodmaps.ie shows an aerial photograph, displaying a large area of agricultural land at Ballylynch, immediately north of the Suir River as flooded. No other information exists about this flood extent or depths so its usefulness is limited to verification of the hydraulic model.

The figure below shows the flood extent at Ballylynch.

Direction photo taken

The 10% AEP modelled extent shown above is slightly wider than the flood extent shown in the photo. This suggests that flooding at Ballylynch was less extreme than a 10% AEP return period. (h) Jan 1996. Review of the historic data found on www.floodmaps.ie indicated that a major flood event occurred in Carrick-on-Suir and Clonmel started on 4 Jan 1996, continuing for several days and eventually subsiding completely on 11 Jan 1996. Tide levels were 900mm higher than predicted, this coupled with an extreme rainfall event over Tipperary and Waterford resulted in flooding in Carrick-on-Suir and Clonmel.

Runoff from agricultural land damaged roads at Ballyrichard. On Saturday 6 January 1996, 200/250mm of flooding occurred on the National 24 Road by Davin Park, however it remained open. River level rose on Saturday afternoon and peaked at 20.30, by now two residential properties in Oven Lane carpark, the school at Clonmel Road, The Filling Station, the Accountants Office and the Vetinary Clinic on Clonmel Road were flooded. By Sunday 7 Jan at 8.00, the N24 at Davin Park had 750mm of flooding on it and was impassable; the Southern end of Mill Street was inundated with 300mm of flooding affecting three residential properties. Two residential properties were flooded at Ash Park and thirteen residential properties were flooded at Markievicz Terrace on Mill Street. Two residential properties on the North Quay and seven residential properties on the South Quay were flooded; one of the properties on the North Quay had never previously been affected by flooding, in its forty years since being built.

Carrick-on-Suir is protected from the Suir River and Glen River up to the 0.5% AEP event since the Carrick-on-Suir Flood Alleviation Scheme was completed. However, during the 1% AEP fluvial modelled event flooding occurs in Carrick-on- Suir. The below figure shows that Mill Street and Clonmel Road are still affected by flooding. However, the North Quay and South Quay are now defended. Due to the construction of the defence, no further calibration can be carried out by this event.

Clonmel Rd. Mill St.

Pre 2003 2% AEP extent

North Quay

South Quay

(i) Dec 1989. Review of the historic data found on www.floodmaps.ie indicates flooding occurred in Portlaw in December 1989. High water levels in the Clodiagh River overtopped banks resulting in flooding on a public road and at a private property. This event resulted in the closure of a road for one week while remedial works costing £30,000 were carried out.

See information about event (c) relating to Portlaw and the Clodiagh.

4.1.4.2 Gauging Stations There are two gauging stations on the model reach:

(a) Fiddown (16061)

This gauging station has reliable tide level record from 1968 to 2012. The Fiddown gauge is tidal and therefore does not have an FSU classification and as such it does was not included in the FSU.

(b) Carrick-on-Suir

This gauging station has reliable tide level records from 1972 to 2012. The Carrick-on-Suir gauge is tidal and therefore does not have an FSU classification and as such it was not included in the FSU.

4.1.4.3 Consultation and Other Information To be completed following Local Authority consultation.

4.1.4.4 Comparison of Flows

PEAK WATER FLOWS

AFA Name Carrick-on-Suir Model Code HA16_SUIR7 Status DRAFT Date extracted from model 10/10/2014

Peak Water Flows

River Name & Chainage AEP Check Flow (m3/s) Model Flow (m3/s) Diff (%) 10 381.29 384.02 0.71 SUIR 7 3858.65 1 485.80 489.15 0.69

0.10 579.00 582.94 0.68 10 382.54 386.17 0.95 SUIR 7 6691.25 1 487.38 491.73 0.89

0.10 580.89 585.90 0.86 10 385.27 386.16 0.23 SUIR 7 7063.00 1 490.86 491.69 0.17

0.10 585.03 585.85 0.14 10 49.97 50.14 0.34 RIVER CLODIAGH 2603.00 1 68.36 68.36 0.03

0.10 86.40 85.78 -0.72 10 10.98 11.54 5.07 RIVER GLEN 3797.39 1 15.35 14.82 -3.46

0.10 19.56 18.23 -6.81 10 11.48 11.73 2.17 RIVER GLEN 5226.67 1 16.04 15.58 -2.89

0.10 20.44 19.98 -2.27 10 11.48 26.84 133.82

RIVER LINGAUN 2371.31 1 16.04 38.32 138.85

0.10 20.44 41.21 101.58 PIL TRIB 1405.32 10 5.91 5.56 -5.83 1 8.22 7.71 -6.23

0.10 10.49 9.82 -6.38 10 18.34 18.91 3.12

RIVER PIL 488.19 1 25.62 26.29 2.60

0.10 32.66 33.45 2.44

The table above provides details of flow in the model at every HEP check point and gauging station.

The modelled peak flows in the Clodiagh River (Ch 2603) are within 1% of the estimated peak flows during all return periods simulated (10%, 1% and 0.1% AEP). The modelled peak flows in the Suir River (Ch 3858.65, 6691.25 and 7063) are within 1% of the estimated peak flows during all return periods simulated (10%, 1% and 0.1% AEP). The modelled peak flows in the Glen River (Ch 5226.67) are within 3% of the estimated peak flows during all return periods simulated (10%, 1% and 0.1% AEP). The modelled peak flows in the Pil River are between 2-3% different when compared to the estimated peak flows during all return periods simulated (10%, 1% and 0.1% AEP). As such for all of these rivers the modelled flows are well anchored to the hydrologically derived peak flow estimates.

The modelled peak flows in the River Pil Tributary (Ch 1405.32) are between 5-6% lower when compared with the estimated peak flows during all return periods simulated (10%, 1% and 0.1% AEP). This difference is no greater than 0.5m3/s and likely caused by a higher degree of hydraulic attenuation than is captured in the design flow estimations. Given that the catchment is small and ungauged it is considered that difference is well within acceptable tolerances and the modelled flows are well anchored to the estimates.

The modelled peak flows in the Glen River (Ch 3797.67) are between 3-5% different when compared to the estimated peak flows for the 10% and 1% AEP return periods. The modelled peak flow during 0.1% AEP return period is 7% different when compared to the estimated peak flow. Given that the catchment is small and ungauged it is considered that difference is well within acceptable tolerances and the modelled lows are well anchored to the estimates.

The modelled peak flows in the Lingaun River are between 101-133% higher than estimated peak flows during all return periods simulated (10%, 1% and 0.1% AEP). During all return periods simulated the River Suir has high water levels which back up into the Lingaun. In this scenario flood extents from the Lingaun and Suir join and as such it is not possible to make a direct comparison between modelled flows and catchment descriptor based hydrological estimates. Hydrological estimates consider only flow emanating from the Lingaun catchment while in the model, flow emanating from the Suir is also passing the point on the modelled Lingaun watercourse which is represented by the HEP.

4.1.4.5 Model Stability Overall the model has limited instabilities. There are a small number of minor instabilities shown in the MIKE 11 results discharge curves; these are at Lingaun River 628 chaiange and in the upper reach of Glen River at 3338 chaiange. These do not have an affect on the water level and are not near any critical structures where they could potentially affect flows.

4.1.4.6 Model Assumptions, Refinements & Limitations

The in-channel roughness coefficients, initially selected based on normal bounds, have been reviewed during the calibration process. Where the model is 1D, both in-channel and floodplain roughness have been represented in the 1D channel. It is assumed that the final selected values are representative. The time-to-peak of inflow hydrographs generated during the hydrological analysis have been reviewed during the calibration process. No adjustments were made. For design run simulations it has been assumed that all culverts and screens are free of debris and sediment. A 2 second time-step for both the MIKE 11 and MIKE 21 models has been selected in order to achieve a successful model simulation for all return periods. The delta factor is set at 0.8 and the Inter1Max is set at 100 in the M11 HD Parameters. A 5m grid Digital Terrain Model was used. The upstream face only of all structures in the model was surveyed and so the upstream face has been duplicated and used as the downstream face of the structure. This is assumed acceptable as all structures were of short length and so there should be minimal difference between the upstream and downstream orifice of each structure. Survey data provided for the MPW stretch of the model was surveyed in the 1960s which is a limitation to this study as the channel shape may have since changed. Cross-sections were extended in the Suir channel, Clodiagh River and Pil River, and Pil tributary using NDHM data which has an accuracy of +/-1.5m. 4.1.4.7 Summary of Model Performance Overall the model performance is satisfactory for assessment of hazard and risk and further option appraisal.

4.1.5 Sensitivity Analysis

To be completed in the final version of the report.

4.1.6 Discussion of Flood Hazard and Mechanisms

This model is influenced by both coastal and fluvial sources, as such a range of events were simulated with fluvial or tidal influences dominating flows. The Q10, Q100 and Q1000 fluvial return periods were simulated, all coinciding with the Q2 tidal event. The Q10, Q200 and Q1000 tidal return periods were also simulated, all coinciding with the Q2 fluvial event.

The Carrick-On-Suir AFA is protected from flooding up to the 2% AEP return period. Modelled results show Carrick-on-Suir to be defended during the 10% AEP return period from the Glen River and the 1% AEP return period from the Suir River. Flooding in Carrick-on-Suir is a result of culvert incapacity in the Glen River; the culverts below John’s Bridge (697J) and the Railway Bridge (662J) are insufficient to convey flood flows (see 1% AEP event longitudinal results below), resulting in flooding within the AFA during the 1% AEP return period. In the Glen River two structures restrict flow but do not result in flooding during the 1% AEP event, these are (418J) at Orchard Street and (218J) at Clonmel Road. The River Glen is the main cause of flooding to the Carrick-on-Suir AFA.

John’s Bridge Railway (697J) Bridge (662J)

The Piltown AFA is not defended against flooding during any AEP return period. The AFA is affected by flooding during all return periods simulated (10%, 1% and 0.1% AEP). Flooding is a result of culvert incapacity in the River Pil. Structures diverting flow under Creamery Road (2775) and Main Street (2860) are insufficient to convey flood flows (see the flood map included in Section 4.1.4.1(f)); constricting flows and causing elevated water levels. The River Pil is the main source of flooding in the Piltown AFA.

The Fiddown AFA has an informal defence on the left bank of the Suir River immediately downstream of Fiddown Bridge. The crest of this defence is above the 1% AEP water level. The Fiddown AFA is largely unaffected by flooding from the Suir, some fluvial flooding occurs on the left bank of the Suir which affects a small agricultural/ silo area.

The Portlaw AFA is not defended against flooding during all return periods simulated (10%, 1% and 0.1% AEP). The River Clodiagh has high water levels which cause a small area of flooding south of the Clodiagh, upstream of the Queen Street Lower/Coolfinn road bridge. The flooding is fluvial with some tidal influence; a backwater effect from the Suir River causes elevated water levels downstream of the bridge. The bridge itself does not restrict flood flows; the flooding in Portlaw AFA is a result of channel incapacity.

4.1.7 Conclusions and Recommendations

To be completed in the final version of the report.

APPENDIX A1 CARRICK-ON-SUIR

Model Reference: HA16_SUIR7 AFAs included in the model: Carrick –on-Suir, Piltown, Fiddown & Portlaw Primary Watercourses / Water Bodies (including local names): Reach ID Name 1 River Glen 2 River Linguan 3 River Pil 4 *named Pil Trib in model 5 *named River Suir Trib 1 in model 6 River Suir *named Suir 7 in model 7 *named River Glen Trib 1 in model 8 River Clodiagh 9 *named River Clodiagh Trib 1 in model 10 *named River Clodiagh Trib 2 in model 11 *named Canal in model. Software Type (and version): (a) 1D Domain : (b) 2D Domain: (c) Other model elements: MIKE 11 (2011) MIKE 21 - Rectangular Mesh MIKE FLOOD (2011) (2011) x-y Coordinates of River (Upstream extent):

River Name x y 1 River Glen 237650 125445 2 River Linguan 241860 122842 3 River Pil 246374 122033 4 *Pil Trib 245250 122928 5 *Suir Trib 1 233800 122800 6 River Suir 230534 123392 7 *River Glen Trib 1 239770 122270 8 River Clodiagh 245593 115515 9 *River Clodiagh Trib 1 246640 114531 10 *River Clodiagh Trib 2 246300 114820 11 Canal 246112 115360

Total Modelled Watercourse Length: 54.12 km (approx.) 1D Domain only Watercourse Length: 35.02 km 1D-2D Domain Watercourse 19.1 km (approx.) Length: (approx.) 2D Domain Mesh Type / Resolution / Area: Rectangular / 5 metres/37.5 km2 (approx.)

Survey Information Survey Folder Structure: First Level Folder Second Level Folder Third Level Folder Survey data was extracted from ISIS model supplied by to RPS by OPW

Survey Folder References:

Reach ID Name File Ref.

Hydraulic Boundary Table:

Hydraulic Model Parameters: MIKE 11 Timestep (seconds) 2 Wave Approximation High Order Fully Dynamic Delta 0.8 MIKE 21

Timestep (seconds) 2 Drying / Flooding depths (metres) 0.02 / 0.03 Eddy Viscosity (and type) 0.25 (Flux Based) MIKE FLOOD Link Exponential Smoothing Factor Default (where non-default value used) Lateral Length Depth Tolerance (m) Default (where non-default value used) Model Handover Notes: All 3 fluvial simulations, and the 10% and 1% AEP tidal events ran successfully. The 0.1% AEP tidal event failed to run due to high water levels were the Lingaun River joins the Suir River. These levels are accurate as the floodplain is deep here. The model was run again with the initial settings file in MIKE set to a maximum water level of 20.

HYDRAULIC MODEL STRUCTURES

1D Structures (in-channel along Number of Bridges and Culverts: 35 modelled watercourses): Number of Weirs:

Structure Details – Bridges and Culverts

SPRING RIVER LENGTH HEIGHT MANNINGS CHAINAGE ID OPENING SHAPE HEIGHT (m) WIDTH (m) BRANCH (m) FROM N INVERT (m) Inistioge Link 260.5 15ILIK00025E 1.48 2.27 5.92 - 0.014

GS 15006 Brownsbarn NORE 51 (15NORE01718D) 2 8.00 2 of 4 ARCHES LW-TABLE 4.12 7.09 0.53 0.014

GS 15006 Brownsbarn NORE 51 (15NORE01718D) 2 8.00 2 of 4 ARCHES LW-TABLE 4.12 7.09 0.53 0.014

Suir 7 17453.9 32221J ------

Pil Trib 1272.5 173 5.00 CROSS-SECTION DB 1.49 3.56 0.31 0.013

Pil Trib 1254 195A 14.00 CROSS-SECTION DB 1.12 4.13 - 0.013

Pil Trib 609.25 883A 8.50 CROSS-SECTION DB 1.94 1.76 0.78 0.013

Pil Trib 549.5 889d 5.00 CROSS-SECTION DB 1.12 2.00 0.51 0.013

Pil Trib 152 1290A 8.00 CROSS-SECTION DB 2.23 2.58 2.02 0.013

River Pil 1388 1799 18.00 8.84 27.54 1.04 0.013 1 of 2 ARCHES CROSS- SECTION DB

1 of 2 ARCHES CROSS- River Pil 1388 1799 18.00 SECTION DB 8.18 21.41 1.11 0.013

1 of 2 ARCHES CROSS- River Pil 402.5 2775 7.00 SECTION DB 1.83 2.66 0.72 0.013

1 of 2 ARCHES CROSS- River Pil 402.5 2775 7.00 SECTION DB 2.00 2.64 0.78 0.013

1 of 2 ARCHES CROSS- River Pil 319.5 2860 9.00 SECTION DB 5.01 4.74 2.36 0.013

1 of 2 ARCHES CROSS- River Pil 319.5 2860 9.00 SECTION DB 3.69 4.80 - 0.013

River Glen Trib 1 225.54 42 ------

River Glen Trib 1 150.035 119 8.07 CROSS-SECTION DB

River Lingaun 1679.2 781J 6.40 CROSS-SECTION DB 4.24 18.4 - 0.013

River Lingaun 628 1831J 6.40 CROSS-SECTION DB 4.20 12.18 - 0.013

River Glen 5253.4 48J 6.82 CROSS-SECTION DB 1.92 3.76 - 0.013

River Glen 5085.845 218J 15.69 CROSS-SECTION DB 1.51 4.61 - 0.013

River Glen 4884.52 418J 9.04 CROSS-SECTION DB 0.73 1.41 - 0.013

River Glen 4810.705 489J ------

River Glen 4713 588J 10.40 CROSS-SECTION DB 1.05 2.04 - 0.013 River Glen 4650 662J 20.00 CROSS-SECTION DB 2.36 3.74 - 0.013

River Glen 4612 697J 18.00 CROSS-SECTION DB 2.18 3.61 - 0.013

River Glen 4418.775 884J 5.55 CIRCULAR 0.89 0.89 - 0.013

River Glen 4223.72 1079 1.44 CROSS-SECTION DB 2.70 8.21 - 0.013

River Glen 2208.23 3095 ------

1 of 2 ARCHES CROSS- River Suir Trib 1 836.68 201 13.73 SECTION DB 0.81 0.54 - 0.013

1 of 2 ARCHES CROSS- River Suir Trib 1 836.68 201 13.73 SECTION DB 0.85 0.62 - 0.013

River Suir Trib 1 661.5 390 23.00 CROSS-SECTION DB 0.87 0.69 - 0.013

River Suir Trib 1 78.27 1013 6.55 CIRCULAR 1.09 0.99 - 0.013

Suir 7 10068 39702J-Road Bridge ------

Suir 7 9769.65 40002-Old Bridge ------

HYDRAULIC MODEL DELIVERABLES

MIKE FLOOD MIKE 21 MIKE 21 RESULTS HA16_SUIR7_MF_CAL_1_10AEP_Fluvial HA16_SUIR7_M21_CAL_1_10AEP_Fluvial HA16_SUIR7_M21_CAL_1_10AEP_Fluvial HA16_SUIR7_MF_CAL_1_1AEP_Fluvial HA16_SUIR7_M21_CAL_1_1AEP_Fluvial HA16_SUIR7_M21_CAL_1_1AEP_Fluvial HA16_SUIR7_MF_CAL_1_01AEP_Fluvial HA16_SUIR7_M21_CAL_1_01AEP_Fluvial HA16_SUIR7_M21_CAL_1_01AEP_Fluvial HA16_SUIR7_MF_CAL_1_10AEP_Tidal HA16_SUIR7_M21_CAL_1_10AEP_Tidal HA16_SUIR7_M21_CAL_1_10AEP_Tidal HA16_SUIR7_MF_CAL_1_1AEP_Tidal HA16_SUIR7_M21_CAL_1_1AEP_Tidal HA16_SUIR7_M21_CAL_1_1AEP_Tidal HA16_SUIR7_MF_CAL_1_01AEP_Tidal HA16_SUIR7_M21_CAL_1_01AEP_Tidal HA16_SUIR7_M21_CAL_1_01AEP_Tidal

MIKE 11 - SIM FILE & RESULTS FILE MIKE 11 - NETWORK FILE MIKE 11 - CROSS-SECTION FILE MIKE 11 - BOUNDARY FILE HA16_SUIR7_M11_CAL_1_10AEP_Fluv HA16_SUIR7_BND_CAL_1_10AEP_Fluv ial HA16_SUIR7_NWK_CAL_1 HA16_SUIR7_XNS_CAL_1 ial HA16_SUIR7_M11_CAL_1_1AEP_Fluvi HA16_SUIR7_BND_CAL_1_1AEP_Fluvi al al HA16_SUIR7_M11_CAL_1_01AEP_Fluv HA16_SUIR7_BND_CAL_1_01AEP_Fluv ial ial HA16_SUIR7_M11_CAL_1_10AEP_Tida HA16_SUIR7_BND_CAL_1_10AEP_Tida l l HA16_SUIR7_M11_CAL_1_1AEP_Tidal HA16_SUIR7_BND_CAL_1_1AEP_Tidal HA16_SUIR7_M11_CAL_1_01AEP_Tida HA16_SUIR7_BND_CAL_1_01AEP_Tida l l MIKE 11 - DFS0 FILE MIKE 11 - HD FILE & RESULTS FILE HA16_SUIR7_HD_CAL_1_10AEP_Fluv Suir7_DFS0_50%AEP_All ial HA16_SUIR7_HD_CAL_1_1AEP_Fluvi Suir7_DFS0_10%AEP_All al HA16_SUIR7_HD_CAL_1_01AEP_Fluv Suir7_DFS0_1%AEP_All ial HA16_SUIR7_HD_CAL_1_10AEP_Tida Suir7_DFS0_01%AEP_All l HA16_SUIR7_HD_CAL_1_1AEP_Tidal HA16_SUIR7_HD_CAL_1_01AEP_Tida HA16_SUIR7_DFS0_Peak at 36hrs l

Quality Assurance: Model Constructed by: Conor Delaney / Laura Howe Model Reviewed by: Stephen Patterson Model Approved by: Grace Glasgow