South Eastern CFRAM Study HA15 Hydraulics Report – DRAFT FINAL

South Eastern CFRAM Study

HA15 Hydraulics Report –

Inistioge Model

DOCUMENT CONTROL SHEET

Client OPW

Project Title South Eastern CFRAM Study

Document Title IBE0601Rp0015_HA15 Hydraulics Report

Model Name Inistioge

Office of Rev. Status Modeller Reviewed by Approved By Issue Date Origin

D01 Draft L. Howe I. Bentley G. Glasgow Belfast/ 07/03/2014 Limerick D02 Draft L. Howe I. Bentley G. Glasgow Belfast/ 06/06/2014 Limerick L. Howe / R. Belfast/ F01 Draft Final K. Smart G. Glasgow 03/02/2015 Clements Limerick L. Howe / R. Belfast/ F02 Draft Final K. Smart G. Glasgow 13/08/2015 Clements Limerick

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Table of Reference Reports Relevant Report Issue Date Report Reference Section South Eastern CFRAM November IBE0601 Rp0001_Flood Risk Review_F01 3.3.8 Study Flood Risk Review 2011 South Eastern CFRAM IBE0601Rp0008_HA 15 Inception Study Inception Report July 2012 4.3.2 Report_F02 UoM15 South Eastern CFRAM October IBE0601Rp0010_HA15_Hydrology Study Hydrology Report 4.9 2013 Report_F01 UoM15 South Eastern CFRAM January IBE0601Rp0016_South Eastern CFRAMS Study HA11-17 SC4 1.1 2014 Survey Contract Report_F01 Survey Contract Report

4 Hydraulic Model Details...... 4-1

4.10 inistioge ...... 4-1

4.10.1 General Hydraulic Model Information ...... 4-1

4.10.2 Hydraulic Model Schematisation ...... 4-2

4.10.3 Hydraulic Model Construction ...... 4-9

4.10.4 Sensitivity Analysis ...... 4-15

4.10.5 Hydraulic Model Calibration and Verification ...... 4-16

4.10.6 Hydraulic Model Assumptions, Limitations and Handover Notes ...... 4-23

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4 HYDRAULIC MODEL DETAILS

4.10 INISTIOGE

4.10.1 General Hydraulic Model Information

(1) Introduction:

The South Eastern CFRAM Study Flood Risk Review report (IBE0601 Rp0001_Flood Risk Review_F01) highlighted Inistioge as an AFA for fluvial and tidal flooding based on a review of historic flooding and the extents of flood risk determined during the PFRA.

Model 9 represents the Inistioge AFAin south County Kilkenny, and encompasses the most downstream reach of the River Nore prior to joining the Barrow Nore Estuary Upper. The Inistioge AFA is affected by the River Nore and a small tributary of the Nore flowing from the west which is also included as a HPW within the model.

The Nore catchment as a whole is predominantly rural. The total contributing area at the downstream limit of the model is 2,519km2 i.e. the entire Nore catchment. 96% of this area enters Model 9 at the upstream limit (downstream output from Thomastown Model 7). TheCroum River is a modelled tributary which meets the Nore within Inistiogeand has a total contributing area of 4.5km2. Downstream of the AFA, several small, steeply sloping tributaries enter the River Nore; the largest of which is the Clodiagh River (14km2). As the model is tidally influenced, the downstream boundary of the model is a tidal hydrograph; further details of this are included in Section 4.10.3(5).

One gauging station, Brownsbarn (15006 – OPW), is located on the modelled reach at the upstream limit of the model. This gauge is an A2 classified station and there is high confidence in it.Further information on the gauge is provided in Section 4.10.5. A CFRAM rating review was undertaken for the gauge; see Section 4.10.5(4)(a) for a full review.

A rainfall runoff model has not been constructed as there is already high confidence in the gauge.This station was used as a pivotal site to adjust the index flows for Model 9. However, in the case of smaller tributaries entering the Nore, a review of pivotal site options revealed that using Station 15006 pushed the resulting Qmedvalues above the 68%ile upper limit. Therefore, as an alternative, the most suitable geographically close station was used (Station 14013 or 15001 as appropriate)for the smaller tributaries.

A number of rivers have been identified as HPW within the Inistioge model, including Croum River, Inistioge Link River and a portion of the Nore River which passes through the AFA. These reaches have been modelled as 1D-2D using the MIKE software suite. Upstream and downstream of the AFA, the Nore River is designated as MPW and has been modelled as 1D. The model has been extended upstream by 800m to enable the rating review of the Brownsbarn (15006) gauging station.

(2) Model Reference: HA15_INIS9

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(3) AFAs included in the model: INISTIOGE

(4) Primary Watercourses / Water Bodies (including local names):

Reach IDName

NORE NORE A

NORE NORE B

ILIK INISTIOGE LINK

COUM THE CROUM

(5) 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)

4.10.2 Hydraulic Model Schematisation

(1) Map of Model Extents:

Figure 4.10.1 and Figure 4.10.2 illustrate the extent of the modelled catchment, river centreline, HEP locations and AFA extents. The Nore catchment contains two Upstream Limit HEP, one Downstream Limit HEP and six Tributary HEPs (one of which is modelled). Brownsbarn (15006) gauging station is located at the upstream extent of the model reach. A rating review is to be carried out for this gauge and so the model has been extended 800m upstream to allow for this.

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Figure 4.10.1: Map of Model Extent

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Figure 4.10.2: Map of Model Extents at the AFA

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(2) x-y Coordinates of River (Upstream extent):

River Name x y NORE NORE 261499 138341 ILIK INISTIOGE LINK 262600 137500 COUM THE CROUM

263690 137635 (3) Total Modelled Watercourse Length: 19.8 (km)

(4) 1D Domain only Watercourse Length: 13.0km (5) 1D-2D Domain 6.8km (approx.) Watercourse Length: (approx.)

(6) 2D Domain Mesh Type / Resolution / Area: Rectangular / 5 metres /9.8 km2

(7) 2D Domain Model Extent:

Figure 4.10.3 2D Model Extent

Figure 4.10.3 shows the extent of the LiDAR data used in the 2D model. For details of the approach to modelling buildings in the 2D area, please refer to Section 3.3.2 of this report.

Figure 4.10.4 shows the extent of the NDHM data used. The black line shows the river network and the red boundary represents the LiDAR extent (as shown in Figure 4.10.3). A buffer zone was created between the two datasets which were smoothed together by interpolation.

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4.10.4 NDHM Extent

Figure 4.10.5shows an overview drawing of the model schematisation. Figure 4.10.6 shows a detailed view of critical structures in the model. The overview design diagram covers the model extents, showing the surveyed cross-section locations, AFA boundary and river centreline. It also shows the area covered by the 2D model domain. The detailed areais provided where there is the most significant risk of flooding. These diagrams include the surveyed cross-section locations, AFA boundary and river centreline. They also show the location of the critical structures as discussed in Section 4.10.3(1) along with the location and extent of the links between the 1D and 2D models.

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4.10.5Model Schematic Overview (A)

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4.10.6 Model Schematic – Critical Structures

(8) Survey Information

(a) Survey Folder Structure:

First Level Folder Second Level Folder Third Level Folder

CCS_S15_M09_15COUM_WP2_Finals_13 15COUM Data Files 0118 15COUM GIS Inistioge 15COUM Photos 15COUM00000_DS CCS – Surveyor Name Photos (Naming S15 – South Eastern CFRAM Study Area, convention is in the Hydrometric Area 15 format of Cross-Section M09 – Model Number 9 ID and orientation -

15COUM– River Reference? upstream, downstream, WP2 – Work Package 2 left bank or right bank)

(b) Survey Folder References:

Reach ID Name File Ref.

NORE NORE A CCS_S15_M09_15NORE_A_WP2_Finals_130118

NORE NORE B CCS_S15_M09_15NORE B_WP2_Finals_130115

ILIK INISTIOGE LINK CCS_S15_M09_15ILIK_WP2_Finals_130118

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COUM THE CROUM CCS_S15_M09_15COUM_WP2_Finals_130118

(9) Survey Issues: There are no known queries with the survey data provided.

4.10.3 Hydraulic Model Construction

(1) 1D Structures (in-channel along See Appendix A.1 modelled watercourses): Number of Bridges and Culverts: 12

Number of Weirs: 0

The survey information recorded includes a photograph of each structure, which has been used to determine the Manning's n value. Further details are included in Chapter 3.5.1. A discussion on the way structures have been modelled is included in Chapter 3.3.4.

Three critical structures have been identified in the model. These are afootbridge (15COUM00044D) (Figure 4.10.7), a road access bridge (15COUM00042I) (Figure 4.10.8), and a culvert near Hatchery Lane (15COUM00026D)(Figure 4.10.9) over the Croum River.

The capacity of these three structures is insufficient to convey flood flows during the modelled events (10%, 1% and 0.1% AEP). All three structures restrict flows causing flow to build up upstream. However, out-of-channel flow only occurs during the 0.1% AEP event; this is due to the high capacity of the Croum River channel.

Figure 4.10.7: Footbridge over Croum River (15COUM00044D)

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Figure 4.10.8: Road access bridge over Croum River (15COUM00042I)

Figure 4.10.9: Culvert over Croum River near Hatchery Lane (15COUM00026D)

The overtopping structure (weir) shown in Figure 4.10.10was not included in the model for the 15COUM00031D culvert due to the headwall being over 3 metres above the culvert soffit, and so overtopping of the structure would not occur.

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Figure 4.10.10: Photograph (left) and survey data (right) of 15COUM00031D

(2) 1D Structures in the 2D domain Four arches were identified in the floodplain(see red ellipse (beyond the modelled watercourses): below in Figure 4.10.11) beneath the R700 road bridge(structure 15NORE01718D) across the Nore River at Brownsbarn town. The structures are included in the model as 2D structures.

Figure 4.10.11: 15NORE01718D (R700 Road Bridge)

(3) 2D Model structures: None

(4) Defences:None

Type Watercourse Bank Model Start Chainage Model End (approx.) Chainage (approx.)

Informal - none

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(5) Model Boundaries - Inflows:

Full details of the flow estimates are provided in the Hydrology Report (IBE0601Rp0010_HA15 Hydrology Report_F02- Section 4.9and Appendix D).The boundary conditions implemented in the model are shown in Table 4.10.1.

Table 4.10.1: MIKE 11 Boundary Information

A review of flows was carried out during the calibration process, and no changeswere made. Further details on how the modelled flows compare with estimated flows in included in Appendix A.3.Figure 4.10.12 provides an example of the associated upstream hydrograph generated for the 0.1% AEP in the Nore River.

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Figure 4.10.12: Upstream Inflow (0.1% AEP)

(6) Model Boundaries – The downstream boundary condition is a tidal hydrograph extracted from Downstream Conditions: the New Ross model (HA14 Model 14) at the confluence of the Nore River and Barrow River.Figure 4.10.13 shows the tide hydrographs used for Model 9.

Figure 4.10.13: Tide curve taken from New Ross(HA14 Model 14)

(7) Model Roughness:

(a) In-Bank (1D Domain) Minimum 'n' value: 0.035 Maximum 'n' value: 0.05

(b) MPW Out-of-Bank (1D) Minimum 'n' value: 0.03 Maximum 'n' value: 0.085

(c) MPW/HPW Out-of-Bank Minimum 'n' value: 0.034 Maximum 'n' value: 0.067

(2D) (Inverse of Manning's 'M') (Inverse of Manning's 'M')

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Figure 4.10.14: Map of 2D Roughness (Manning's n)

Figure 4.10.14 illustrates the roughness values applied within the 2D domain of the model. Roughness in the 2D domain was applied based on land type areas defined in the CORINE Land Cover Map with representative roughness values associated with each of the land cover classes in the dataset.

(d) Examples of In-Bank Roughness Coefficients

The Croum River – 15COUM00041J The Croum River – 15COUM00066

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Figure 4.10.15: 15COUM00041JRoughness Figure 4.10.16: 15COUM00066 Roughness

Manning’s n = 0.04 Manning’s n = 0.05

Standard natural stream or river in stable condition, Standard natural stream or river in stable condition, with some weeds and stones with some weeds and large amount of stones

Inistioge Link River – 15ILIK00026 Nore River – 15NORE01403

Figure 4.10.17: 15ILIK00026 Roughness Figure 4.1. 1 15NORE01403Roughness

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

Standard natural stream or river in stable condition Standard natural stream or river in stable condition,

4.10.4 Sensitivity Analysis

Sensitivity analysis to be reported in Final Version of report (F02), as agreed with OPW.

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4.10.5 Hydraulic Model Calibration and Verification

(1) Key Historical Floods (fromIBE0601Rp0008_HA15 Inception Report_D02, unless otherwise specified):

NOV 2009 A review of historical flood events indicated that flooding occurred in Thomastown and Inistioge on 19th November 2009. However, details of the flood extents are not available. At Brownsbarn hydrometric station (15006), located between these two AFAs, the peak flow measured during this event was 396m3/s, which is close to the modelled peak flow of a 10% AEP fluvial event (coincides with 50% AEP tidal event)of 415.97m3/s.

A review of the 10% AEP model results shows Inistioge town to experience flooding during this event, see Figures 4.10.19 and 4.10.20 and the flood maps.

th JAN 2008 A Review of the historical data indicated that a flood event occurred on 10 January 2008 ATThomastown and Inistioge. At the Met Eireann weather station in Kilkenny, 33.6mm of heavy rain fell mainly during a 12 hour period on 9th to 10th January and caused the Nore to burst its banks. In Inistioge, the R700 was flooded. Flood gates saved several houses from flooding. In the case of one house, the gate was not put in place in time. The quay area was flooded to a depth of 300mm.

At the Brownsbarn hydrometric station (15006), locatedbetween the Thomastown and Inistioge AFAs, the recorded peak flow was 364.71 m3/s which is close to the modelled peak flow of a 10% AEP Fluvial event (coincides with 50% AEP tidal event)of 415.97m3/s.

Model results show the R700 is inundated with floodwaters in Inistioge town during the 10% AEP fluvial (coincides with 50% AEP tidal) event. The quay area, adjacent to the R700 Inistioge road bridge, is also inundated with waters up to a depth of 950mm,see Figures 4.10.19 and 4.10.20 and the flood maps.

NOV 2000 The historical review indicated that a flood event occurred in Ballyragget, Kilkenny, Thomastown, Inistioge, and Ballyhale in November 2000. The flooding was caused by heavy rainfall causing the River Nore to overflow. References to flooding in Thomastown, Inistioge and Ballyhale on this date were also found. The N9 at Ballyhale was closed.

A peak flood level of 8.0mOD (Malin), and a corresponding peak flow of 376m3/s,were recorded at the Brownsbarn hydrometric station (15006). This flow is close to a modelled 10% AEP fluvial event (coincides with 50% tidal event) at the Brownsbarn Gauge, of415.97m3/s.

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No further information was found on the damage caused to these towns.

During the 10% AEP fluvial (coincides with 50% tidal) event, the peak flow at Brownsbarn gauge is 415.97m3/s. A review of the 10% AEP model results shows Inistioge town to experience flooding during this event, see Figures 4.10.19 and 4.10.20 and the flood maps.

th JAN 1996 Kilkenny, Callan, Thomastown and Inistiogeexperienced flooding on 6 January 1996 following heavy rainfall.References to flooding in Inistioge, where the Green and GAA pitch were flooded, were found. At the Brownsbarn Hydrometric Station (between Thomastown and Inistioge) on 7th January, the peak flood level reached 8.06mOD (Malin) with a corresponding peak flow of 388m3/s.

At the Brownsbarn hydrometric station (15006),between theThomastown and Inistioge AFAs, the recorded peak flow was 388 m3/s which is close to the modelled peak flow of a 10% AEP fluvial event (coincides with 50% AEP tidal event) of 415.97m3/s.

A review of the 10% AEP model results shows that the GAA pitch and green experience flooding up to depths of 1.8m during this event, see Figures 4.10.19 and 4.10.20 and the flood maps.

DEC 1960 Review of the historical data indicated that flooding occurred in Kilkenny, Callan, Thomastown and Inistioge on 1st December 1960 caused by heavy rainfall and snowmelt. In Inistioge, houses were flooded to a depth of 3 to 4 feet. At Brownsbarn Hydrometric Station (15006), between Thomastown and Inistioge, a peak flood level of 8.24mOD (Malin) was recorded.The peak recorded flow was 411 m3/s, which is close to the modelled peak flow of a 10% AEP fluvial event (coincides with 50% AEP tidal event) of 415.97m3/s.

A review of the 10% AEP model results shows that houses off the R700, adjacent to The Square, experience flooding up to 1m (approx. 3-4 ft); see Figures 4.10.19 and 4.10.20 and the flood maps. All buildings were removed from the floodplain and so the exact depths in the houses cannot be calculated.

th MAR 1947 A major flood event was found to have occurred on 14 March 1947 in Freshford, Kilkenny, Callan, Thomastown and Inistioge.In Inistioge, the lower part of the village was flooded to a depth of five feet. Ten houses were affected. No information on flows or levels was found.

During the 10% AEP fluvial event (coincides with 50% tidalevent), peak flood depths of 1.5m (approx. 5 ft) are shown in the lower part of Inistioge near the Nore River. Over a dozen houses are shown to be affected during this event, see Figures 4.10.19

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and 4.10.20 and the flood maps.

OCT 1763 A review of the historical data indicated that flooding occurred in Kilkenny, Thomastown and Inistioge on 2nd October 1763 caused by 24 hours of incessant rain. It was reported that every bridge on the Nore was washed away except for one in Ballyragget and one in Inistioge, which was badly damaged (Kilkenny County Council Report, Jul 1985).This is the worst known flood in the history of the area.

During all simulated fluvial events (10%, 1% and 0.1% AEP fluvial events coinciding with 50% tidal event), the two bridges on the model reach (the R700 road bridge at Brownsbarn and the R700 bridge at Inistioge town) are inundated with floodwaters suggesting damage to the original bridges is likely, see Figures 4.10.19 and 4.10.20 and the flood maps.

No flow or level data is available for calibration.

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R700 Bridge at Brownsbarn NORE RIVER

Figure 4.10.18 Modelled 10% AEP flood extent and depths (metres) at the R700 road bridge adjacent to Brownsbarn village.

GAA PITCH

NORE RIVER The Square

R700

Figure 4.10.19 Modelled 10% AEP flood extent and depths (metres) in Inistioge town; the R700 road is indicated with a red line.

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Summary of Calibration There are a number of historic flood events to calibrate/validate the model to in the AFA. The model results are well validated at the 10% AEP return period. However, there is limited gauge data with relevant flood information (extents, depths) for the higher return periods, so calibration/validationis limited to lower flow (10% AEP) events.

A rating review was carried out for the Brownsbarn gauging station (15006). Brownsbarn calibrates well with the recorded rating review and has therefore been used for calibration with historical events.

A mass balance check has been carried out on the model to ensure that the total volume of water entering and leaving the model at the upstream and downstream boundaries balances with the quantity of water remaining in the domain at the end of the simulation. The mass error in the 1% AEP design run was found to be -0.3%, which is within acceptable limits (Section 3.11 of this report details acceptable limits).

Model flows were validated against the estimated flows at HEP check points to ensure the model is well anchored to hydrological estimates. However, as the downstream extent of the model (HEP 15_1839_1) is a tidal boundary it is not possible to validate. A test model was run using the 0.1% AEP inflows and the downstream boundary set to a Q-h boundary. The modelled peak flow at HEP 15_1839_1 is within 5% of the estimated peak flow (824.68 m3/s) at HEP 15_1839_1. As such, the model is considered well anchored to the hydrological estimates.

There are no significant instabilities shown in the model results. Overall, the model is performing well and is supported by historic information.

(2) Public Consultation Comments and Response:

To be completed for final version of the report (F02).

(3) Standard of Protection of Existing Formal Defences:

Defence Type Watercourse Bank Modelled Standard Reference of Protection (AEP)

None

(4) Gauging Stations:

(a) Brownsbarn (15006)

Gauging station 15006 is located in County Kilkenny on the River Nore. Figure 4.10.21 shows the location of the gauge.

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Figure 4.10.20Brownsbarn (15006) Gauging Station Location

This gauging station has an FSU rating of A2, suggesting that there is confidence in the rating up to 3 approximately 1.3 times the Qmed. For FSU, a Qmedvalue of 299.3 m /s was extracted from records between 1972 and 2011. The OPW have assigned the rating standard at the Brownsbarn station a data quality code of 36 up to 1.37 m, and a data quality code of 56 from 1.37m up to 3.23 m above staff gauge zero.

A rating review was carried out for this gauge. During calibration the model was adjusted to achievebest fit of the modelled rating to the highest flow spot gauging (316.52 m3/s; stage 3.395 m, 7.79 m OD Malin).During initial calibration of the model, a lack of agreement between the modelled rating and the OPW rating in the low flow Q-h range was found, regardless of the roughness values used. Only the upstream face cross-section of the bridge structure was surveyed and a review of the cross-sections downstream of the bridge suggests that there may be a high point in the channel at a location downstream of the bridge, which was not captured in the survey, and which controls the low stage Q-h relationship. To account for this, a cross-section was interpolated downstream of the bridge structure with the bed levels raised until agreement could be achieved with the low flow spot gaugings.This low flow control point was investigated and a cross-section was surveyed at the location,this cross-section is now included in the model in place of the interpolated section. A Manning’s n value of 0.028 on the cross-section at the gauge was required for the model to replicate the existing OPW spot gaugings. This is slightly lower than the usual value of 0.03 for a clean, straight channel with minimal vegetation on the banks. A review of survey photographs and aerial photographs of the river confirmed that this is an appropriate value for this reach.

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A Manning’s n value of 0.02 was applied to each of the arches comprising the bridge structure, and an inflow loss coefficient of 0.3 was applied to each arch. After applying these values, the model Q-h represented the existing OPW rating fairly well.

The gauging station is located on a HPW reach, and as such the model has been constructed from surveyed cross-sections in the 1D channel of the model, and LiDARDTM representing the 2D floodplain. Flow is accurately represented both in-channel and within the floodplain. The model produced a stable rating curve up to 799.19 m3/s (stage 3.43 m; 9.58 m OD Malin). The rating curve for the 1D-2D linked model is considered reliable up to 799.19 m3/s (stage 3.43 m; 9.58 m OD Malin), which is an estimated 0.1% AEP flow.

The results of the rating curve are shown in Figure 4.10.22. The graph depicts the RPS modelled rating curve against the OPW rating curve. The graph shows that the model accurately represents the OPW rating curve based on the highest flow spot gaugings up to the highest spot gauging 317.15 m3/s (stage 3.43; 7.2 m OD Malin). The model passes through the highest flow spot gauging and can be considered well calibrated to the spot gaugings.

4.10.21 Comparison of Existing OPW Rating Curve, RPS Rating Curve and Spot Gaugings

(5) Other Information:

None

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4.10.6 Hydraulic Model Assumptions, Limitations and Handover Notes

(1) Hydraulic Model Assumptions: a) The in-channel, structure and floodplain roughness coefficients, initially selected based on normal bounds, were reviewed using aerial photography and survey data during the calibration process. It is considered that the selected values are representative.

(b) The time-to-peak of inflow hydrographs generated during the hydrological analysis have been reviewed during the calibration process. No changes were made to flows.

(c) For design run simulations it has been assumed that all culverts and screens are free of debris and sediment.

(d) No overtopping structure (weir) was included for the 15COUM00031D culvert as the headwall is over 3 metres above the culvert soffit (see photograph in Section 4.10.3(1). The 0.1% AEPevent flow does not reach this level, and as such it is assumed acceptable to exclude the overtopping structure from the model. e) It should be noted that observed flooding of rural roads and outlying properties may be represented less accurately than flooding within the AFA. The MPW was modelled using cross-section data only and the cross-sections did not contain enough data on the left and right banks. As water levels increased, the floodplain was not accurately represented as water was not able to spill as required. The majority of the cross-sections on the Nore River (from chainage 6902.19 m to 17323 m)were extended with the use of the NDHM to provide enough information on the floodplain and to allow water to spill as necessary. Background mapping from the NDHM wasapplied to the MPW which allowed for more accurate floodplain representation between the 1D cross sections. Specific areas where floodwaters were subject to glass- walling beyond the 1D cross sectionswere connected to the nearest cross-section to produce a more accurate mapping output. It should be noted that this method simply projects the water level from the associated cross-section onto the topography. This methodology is further discussed in Section 3; essentially it provides no attenuation for the MPW but provides improved mapping. This is reflected in the model check flows which are discussed in Appendix A.3.

(2) Hydraulic Model Limitations and Parameters:

Hydraulic Model Parameters:

MIKE 11

Timestep (seconds) 1

Wave Approximation High Order Fully Dynamic

Delta 0.85

MIKE 21

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Timestep (seconds) 1

Drying / Flooding depths (metres) 0.02 / 0.03

Eddy Viscosity (and type) 0.5 (Flux Based)

MIKE FLOOD

Link Exponential Smoothing Factor River Nore, Ch 2362-3478 and 4072-4975: 0.8.

(where non-default value used)

Lateral Length Depth Tolerance (m) Default

(where non-default value used)

(3) Design Event Runs & Hydraulic Model Handover Notes:

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 10%, 1% and 0.1% AEP fluvial events were simulated, all coinciding with the 50% AEP tidal event. The 10%, 0.5% and 0.1% AEP tidal events were also simulated, all coinciding with the 50% AEP fluvial event.

There are three critical structures in the model, all located in the AFA along the Croum River; these are 15COUM00044D (Footbridge over River Croum), 15COUM00042I (Road Access bridge over River Croum) and 15COUM00026D (Culvert under Hatchery Lane), which restrict flows during all return periods (10%, 1% and 0.1% AEP). Out-of-bank flooding only occurs in the 0.1% AEP event, due to the large capacity of the Croum River, and affects approximately 10 properties.

During the fluvial events in Inistioge town, the capacity of the Croum River is shown to be adequate for most return periods (10% and 1% AEP). A limited amount of out-of-channel flooding occurs during the 0.1% AEP event, flooding a small number of properties on Hatchery Lane and Mill Road. During the tidal events in Inistioge town, the capacity of the Croum River is shown to be adequate for all modelled return periods (10%, 0.5% and 0.1% AEP).

Extensive out-of-channel flooding occurs from the Nore River and Inistioge Link stream during all modelled fluvial and tidal return periods along the entire AFA and HPW reach. A longitudinal section included in Appendix A.2 shows water levels in the AFA during the 1% AEP event.Flooding occurs adjacent to the GAA grounds, across a section of the R700 road through Inistioge town, and at approximately six properties in the AFAduring all modelled fluvialand tidal return periods. This is due to lack of capacity in the Nore River during high flows.

Upstream and downstream of the AFA,extensive flooding occurs due to lack of capacity in the Nore River. The majority of the land flooded is grassland with minimal flooding to properties. During all return periods (10%, 1% and 0.1% AEP fluvial; 10%, 0.5% and 0.1% AEP tidal), significantflooding originates from the Inistioge Link stream and the Nore River, extending 1km downstream from its confluence with the downstream extent of the Inistioge link channel. This flooding is between 2m and 3m deep, affecting grassland and agricultural land adjacent to the River Nore.

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(4) Hydraulic Model Deliverables:

Please see Appendix A.4 for a list of all model files provided with this report.

(5) Quality Assurance:

Model Constructed by: Laura Howe

Model Reviewed by: Stephen Patterson

Model Approved by: Malcolm Brian

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APPENDIX A.1 MODELLED STRUCTURES

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Structure Details – Bridges & Culverts SPRING HEIGHT RIVER LENGTH OPENING SHAPE HEIGHT WIDTH MANNING’S CHAINAGE ID FROM BRANCH (m) (m) (m) n INVERT (m) Culverts Inistioge Link 260.5 15ILIK00025E 1.48 CROSS-SECTION DB 2.27 5.92 - 0.014 Inistioge Link 283 15ILIK00023D 3.4 CROSS-SECTION DB 2.58 5.25 - 0.014 NORE 3481 15NORE01378D 1 6.5 1 of 10 ARCHES LW-TABLE 5.21 6.59 1.67 0.014 NORE 3481 15NORE01378D 2 6.5 1 of 10 ARCHES LW-TABLE 5.55 7.04 1.82 0.014 NORE 3481 15NORE01378D 3 6.5 2 of 10 ARCHES LW-TABLE 5.81 6.93 2.33 0.014 NORE 3481 15NORE01378D 5 6.5 2 of 10 ARCHES LW-TABLE 5.74 7.32 2.16 0.014 NORE 3481 15NORE01378D 6 6.5 1 of 10 ARCHES LW-TABLE 5.96 7.18 2.23 0.014 NORE 3481 15NORE01378D 7 6.5 1 of 10 ARCHES LW-TABLE 5.19 7.29 1.62 0.014 NORE 3481 15NORE01378D 8 6.5 1 of 10 ARCHES LW-TABLE 4.37 7.35 0.27 0.014 NORE 3481 15NORE01378D 9 6.5 1 of 10 ARCHES LW-TABLE 4.01 7.24 0.00 0.014 THE COUM 768.2 15COUM00044D 2.3 CROSS-SECTION DB 1.22 1.95 - 0.014 THE COUM 801 15COUM00042I 5.6 2CIRUCLAR 0.6 0.6 - 0.013 THE COUM 861.67 15COUM00035D 1.3 CROSS-SECTION DB 1.61 2.68 - 0.014 THE COUM 913 15COUM00031D 18.7 ARCHES CROSS-SECTION DB 1.63 2.44 0.91 0.014 THE COUM 964 15COUM00026D 10.48 ARCHES CROSS-SECTION DB 1.58 2.43 1.07 0.014 THE COUM 1020 15COUM00023D 72.98 CROSS-SECTION DB 1.05 3.67 - 0.014 THE COUM 1088 15COUM00014I 9.8 CROSS-SECTION DB 0.77 2.71 - 0.014 THE COUM 1214.2 15COUM00001D 0.72 ARCHES CROSS-SECTION DB 1.18 2.28 0.50 0.015 GS 15006 Brownsbarn NORE 51 8 1 of 4 ARCHES LW-TABLE 4.12 7.09 0.53 0.02 (15NORE01718D) 2 GS 15006 Brownsbarn NORE 51 8 1 of 4 ARCHES LW-TABLE 7.88 12.82 3.93 0.02 (15NORE01718D) 3 GS 15006 Brownsbarn NORE 51 8 1 of 4 ARCHES LW-TABLE 7.54 12.80 3.64 0.02 (15NORE01718D) 4 GS 15006 Brownsbarn NORE 51 8 1 of 4 ARCHES LW-TABLE 6.86 13.00 2.97 0.02 (15NORE01718D) 1

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APPENDIX A.2

RIVER LONG SECTION PROFILES

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River Nore 1% AEP Peak Water Levels

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APPENDIX A.3

ESTIMATED PEAK FLOW AND MODEL FLOW COMPARISON

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IBE0601 SE CFRAM STUDY RPS PEAK WATER FLOWS

AFA Name INISTIOGE Model Code HA15_INIS9 Status DRAFT FINAL Date extracted from model 27/01/2015

Peak Water Flows (FLUVIAL)

Check Flow Model Flow River Name &Chainage AEP (m3/s) (m3/s) Diff (%) THE COUM 1223.45 10% 2.30 35.80 1458.04

15_1996_1 1% 4.23 74.09 1652.82

0.1% 7.51 114.69 1427.82

NORE 17298.6 10% 424.71 840.12 97.81

15_1839_1 1% 598.88 871.84 45.58

0.1% 824.68 1153.30 39.85

Peak Water Flows (TIDAL)

Check Flow Model Flow River Name &Chainage AEP (m3/s) (m3/s) Diff (%) THE COUM 1223.45 10% 2.30 14.58 534.46

15_1996_1 1% 4.23 14.60 245.45

0.1% 7.51 14.63 94.83

NORE 17298.6 10% 424.71 664.41 56.44

15_1839_1 0.5% 598.88 757.96 26.56

0.1% 824.68 760.98 7.72

The table above provides details of flow in the model at every HEP check point, modelled tributary and gauging station. These flows have been compared with the hydrology flow estimation and a percentage difference provided.

The modelled peak flow at HEP 15_1996_1 (CoumCh 1223.45) is between 1,427% and 1,652% different when compared with the estimated peak flow in the fluvial events 10%, 1% and 0.1% AEP. IBE0601Rp0015 4.10 - 31 F02 South Eastern CFRAM Study HA15 Hydraulics Report – DRAFT FINAL

The modelled peak flow is between 94% and 534% different when compared with the estimated peak flows during the 10%, 0.5% and 0.1% AEP tidal events. During these simulated events (10%, 1% and 0.1% Fluvial; 10% 0.5% and 0.1% AEP Tidal) the River Nore has very high water levels which exceed channel capacity on the right bank, flowing overland and connecting with the Croum River (upstream of the HEP) resulting in significant increases in modelled peak flow. This overland flow is the reason for the higher than estimated peak flows.

The River Nore downstream of HEP 15_2002_9 is heavily tidally influenced and therefore reliable flow estimation is not possible. As a result, the difference between modelled flow and estimated flow at the downstream HEP 15_1839_1 is large. However, this difference was not considered to be significant, especially as the mass balance calculations do not indicate significant gains or losses of flow from the model.

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APPENDIX A.4

DELIVERABLE MODEL AND GIS FILES

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MIKE FLOOD MIKE 21 MIKE 21 RESULTS HA15_INIS9_MF_DES_1_F_Q10 HA15_INIS9_M21_DES_1_F_Q10 HA15_INIS9_M11_DES_1_F_Q10 HA15_INIS9_MF_DES_1_F_Q100 HA15_INIS9_M21_DES_1_F_Q100 HA15_INIS9_M11_DES_1_F_Q100 HA15_INIS9_MF_DES_1_F_Q1000 HA15_INIS9_M21_DES_1_F_Q1000 HA15_INIS9_M11_DES_1_F_Q1000 HA15_INIS9_MF_DES_1_T_Q10 HA15_INIS9_M21_DES_1_T_Q10 HA15_INIS9_M11_DES_1_T_Q10 HA15_INIS9_MF_DES_1_T_Q200 HA15_INIS9_M21_DES_1_T_Q200 HA15_INIS9_M11_DES_1_T_Q200 HA15_INIS9_MF_DES_1_T_Q1000 HA15_INIS9_M21_DES_1_T_Q1000 HA15_INIS9_M11_DES_1_T_Q1000

MIKE 11 - SIM FILE & RESULTS FILE MIKE 11 - NETWORK FILE MIKE 11 - CROSS-SECTION FILE MIKE 11 - BOUNDARY FILE HA15_INIS9_M11_DES_1_F_Q10 HA15_INIS9_NWK_DES_1 HA15_INIS9_XNS_DES_1 HA15_INIS9_BND_DES_1_F_Q10 HA15_INIS9_M11_DES_1_F_Q100 HA15_INIS9_BND_DES_1_F_Q100 HA15_INIS9_M11_DES_1_F_Q1000 HA15_INIS9_BND_DES_1_F_Q1000 HA15_INIS9_M11_DES_1_T_Q10 HA15_INIS9_BND_DES_1_T_Q10 HA15_INIS9_M11_DES_1_T_Q200 HA15_INIS9_BND_DES_1_T_Q200 HA15_INIS9_M11_DES_1_T_Q1000 HA15_INIS9_BND_DES_1_T_Q1000 MIKE 11 - DFS0 FILE MIKE 11 - HD FILE & RESULTS FILE* HA15_INIS9_TS_Q2(140224)peaks moved HA15_INIS9_HD_DES_1_F_Q10 HA15_INIS9_TS_Q10(140224)peaks moved HA15_INIS9_HD_DES_1_F_Q100 HA15_INIS9_TS_Q100(140224)peaks moved HA15_INIS9_HD_DES_1_F_Q1000 HA15_INIS9_TS_Q1000(140224)peaks moved HA15_INIS9_HD_DES_1_T_Q10 HA15_INIS9_TS_Tide Curve HA15_INIS9_HD_DES_1_T_Q200 HA15_INIS9_HD_DES_1_T_Q1000

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GIS Deliverables - Hazard

Flood Extent Files (Shapefiles) Flood Depth Files (Raster) Water Level and Flows (Shapefiles) Fluvial Fluvial Fluvial& Tidal O20EXFCD001C0 o20dpfcd001c0 O20NCCDC0 O20EXFCD010C0 o20dpfcd010c0 O20EXFCD100C0 o20dpfcd100c0

Tidal Tidal O20EXCCD001C0 o20dpccd001c0 O20EXCCD005C0 o20dpccd005c0 O20EXCCD100C0 o20dpccd100c0 Flood Zone Files (Shapefiles) Flood Velocity Files (Raster) Flood Defence Files (Shapefiles) To be issued with Final version of this report (F02) Defended Areas O20ZNA_MCDC0 NA O20ZNB_MCDC0 Defence Failure Extent NA

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