South Eastern CFRAM Study HA15 Hydraulics Report – DRAFT FINAL South Eastern CFRAM Study HA15 Hydraulics Report Kilkenny Model DOCUMENT CONTROL SHEET Client OPW Project Title South Eastern CFRAM Study Document Title IBE0601Rp0015_HA15 Hydraulics Report Model Name Kilkenny Approved Rev. Status Author(s) Modeller Reviewed by Office of Origin Issue Date By D01 Draft T. Carberry L. Howe I. Bentley G. Glasgow Limerick/Belfast 01/07/2014 Draft L. Howe / L. Howe / F01 K. Smart G. Glasgow Belfast 14.04.2015 Final R. Clements R. Clements Draft L. Howe / L. Howe / F02 K. Smart G. Glasgow Belfast 13/08/2015 Final R. Clements R. Clements IBE0601Rp0015 F02 South Eastern CFRAM Study HA15 Hydraulics Report – DRAFT FINAL Table of Reference Reports Relevant Report Issue Date Report Reference Section South Eastern CFRAM November 3.3.9 IBE0601 Rp0001_Flood Risk Review_F01 Study Flood Risk Review 2011 3.3.10 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 4.5 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.................................................................................................................... 1 4.1 Kilkenny model ........................................................................................................................ 1 4.1.1 General Hydraulic Model Information .................................................................................. 1 4.1.2 Hydraulic Model Schematisation ......................................................................................... 3 4.1.3 Hydraulic Model Construction ............................................................................................ 10 4.1.4 Sensitivity Analysis ............................................................................................................ 20 4.1.5 Hydraulic Model Calibration and Verification ..................................................................... 21 4.1.6 Hydraulic Model Assumptions, Limitations and Handover Notes ...................................... 37 IBE0601Rp0015 F02 South Eastern CFRAM Study HA15 Hydraulics Report – DRAFT FINAL 4 HYDRAULIC MODEL DETAILS 4.1 KILKENNY MODEL 4.1.1 General Hydraulic Model Information (1) Introduction: The South Eastern CFRAM Flood Risk Review (IBE0601 Rp0001_Flood Risk Review_F01) highlighted Kilkenny, in the Nore catchment, as an AFA for fluvial flooding based on a review of historic flooding and the extents of flood risk determined during the PFRA. Model 5 represents the Kilkenny AFA and encompasses the mid to lower reaches of the River Nore, River Baun, River Breagagh, River Pococke, River Kingsland, and associated tributaries the River Cellar, and Ardboy Stream. The Kilkenny AFA is affected by these watercourses. The River Breagagh joins the River Nore from the west in Kilkenny city; the River Pococke meets the Nore at the downstream end of the AFA. The River Baun joins the Nore just north of the AFA, and the River Kingsland just south of the AFA. The Ballyragget model is located upstream and the Thomastown model is located downstream of the Kilkenny model. All three models are sited on the River Nore. The total contributing area at the downstream limit of the model is 1744.5km2. 71% of this area comprises the upstream Ballyragget model. A significant tributary, the River Dinin, enters the River Nore at the upstream limit of the Kilkenny model (where the Ballyragget model ends). The contributing area of the River Dinin catchment is almost 300km2 and makes up 17% of the total catchment area for the model. A further 4% of the total contributing area comes from the River Breagagh catchment, and 2% from the River Pococke catchment. There are three gauging stations on the River Nore within the Kilkenny model: • Station 15104 Sycamores – OPW – no flow or level data available • Station 15002 Johns Bridge – OPW – was classified “A2” under FSU in 2004 - there is confidence 3 in flow values up to around 1.3 times Qmed. Qmed gauged is 216 m /s (based on AMAX series from 1953 to 2009, but missing 2002 – 2005 during flood relief works). • Station 15105 Archers Grove – OPW – no flow or level data available There is one gauging station on the River Breagagh within the Kilkenny model: • Station 15050 Blackfriar’s Bridge – OPW – classified “C” under FSU, therefore confidence in flow values only extends to 0.8 x Qmed. The OPW hydrometrics team have also advised that the rating is not reliable post May 2004. A new rating is required following the installation of a data logger following the flood relief works at the end of 2005. The FSU ungauged catchment descriptor 3 based equation predicts Qmed at 8.02 m /s. The OPW have not requested a rating review for this IBE0601Rp0015 4.6 - 1 F02 South Eastern CFRAM Study HA15 Hydraulics Report – DRAFT FINAL gauging station to be undertaken as part of the Study. However rainfall runoff modelling was 3 undertaken for this station during hydrological analysis which yielded a Qmed value of 11.1m /s that carries greater statistical certainty (Refer to UoM 15 Hydrology Report (IBE0601Rp0010) for details). Initial Qmed estimates at the various HEPs were adjusted based on the gauges at John’s Bridge (Station 15002 - Nore) or Blackfriar’s Bridge (Station 15050 - Breagagh). However the initially estimated index flow from the Dinin River was adjusted using the upstream pivotal site at Dinin Bridge (Station 15003). Refer to UoM 15 Hydrology Report (IBE0601Rp0010) for full details on hydrology estimation. The Kilkenny Flood Relief Scheme was completed in 2005. It consisted of a combination of river widening and deepening, flood walls, embankments and associated drainage works. A number of rivers have been identified as HPW within the Kilkenny Model, including Ardboy River, Baun River, Breagagh River, Cellar River, Crokershill Link River, Kingsland River, Pococke River, Robertshill Link River and a portion of the River Nore which passes through the AFA. These reaches have been modelled as 1D-2D using the MIKE suite of software. Upstream and downstream of the AFA, the River Nore is designated as MPW and has been modelled as 1D. (2) Model Reference: HA15_KILK5 (3) AFAs included in the model: KILKENNY (4) Primary Watercourses / Water Bodies (including local names): Reach ID Name 15NORE NORE_E 15POCO POCOCKE 15ROBE ROBERTSHILL LINK 15ARDB ARDBOY (STREAM) 15BAUN BAUN_A 15BAUN BAUN_B 15BREA BREAGAGH 15CELL CELLAR 15CROK CROKERSHILL LINK 15KLND KINGSLAND 15NORE NORE_F (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) IBE0601Rp0015 4.6 - 2 F02 South Eastern CFRAM Study HA15 Hydraulics Report – DRAFT FINAL 4.1.2 Hydraulic Model Schematisation (1) Map of Model Extents: Figure 4.1.1: Overview Map of Model Extents – Kilkenny Model Figure 4.6.1 illustrates the extent of the modelled catchment, the river centre line, HEP locations and AFA extents. The Nore catchment contains 7 Upstream Limit HEPs, 1 Downstream Limit HEP, 3 Intermediate HEPs, 8 Tributary HEPs (five of which are modelled) and 2 Gauging Station HEPs. IBE0601Rp0015 4.6 - 3 F02 South Eastern CFRAM Study HA15 Hydraulics Report – DRAFT FINAL Figure 4.1.2: Enlarged View of the Kilkenny Model at the AFA (2) x-y Coordinates of River (Upstream extent): River Name x y 15NORE NORE_E 254225 153205 15POCO POCOCKE 252700 158000 15ROBE ROBERTSHILL LINK 249280 455835 15ARDB ARDBOY (STREAM) 247990 157340 15BAUN BAUN_A 250281 158960 15BAUN BAUN_B 250735 159090 15BREA BREAGAGH 248745 153180 15CELL CELLAR 253825 157020 15CROK CROKERSHILL LINK 249425 156050 15KLND KINGSLAND 254300 155720 15NORE NORE_F 249555 159415 (3) Total Modelled Watercourse Length: 37.17 (km) IBE0601Rp0015 4.6 - 4 F02 South Eastern CFRAM Study HA15 Hydraulics Report – DRAFT FINAL (4) 1D Domain only Watercourse Length: 7.43 (km) (5) 1D-2D Domain 29.74 Watercourse Length: (km) (6) 2D Domain Mesh Type / Resolution / Area: Rectangular / 5 metre / 56.33 (km2) (7) 2D Domain Model Extent: Figure 4.1.3: 2D Model Domain - Kilkenny Model Figure 4.6.3 shows the extent of the LiDAR data used in the 2D model. Buildings are excluded from the mesh and are therefore represented as black spaces - please refer back to Chapter 3.3.2 for further details on the representation of buildings in the model. Figure 4.6.4 shows the extent of the NDHM data used. The black line shows the river network and the red boundary represents the LiDAR extent (also seen in Figure 4.6.3). A buffer zone was created between the two datasets which were smoothed together by interpolation. IBE0601Rp0015 4.6 - 5 F02 South Eastern CFRAM Study HA15 Hydraulics Report – DRAFT FINAL Figure 4.1.4: NDHM Extent – Kilkenny Model Figure 4.6.5 shows an overview of the model schematisation. Figure 4.4.6 provides a more detailed view. The overview diagram covers the model extents, showing the surveyed cross-section locations, AFA boundary and river centrelines. It also shows the area covered by the 2D model domain. The detailed view has been provided for the area 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 4.6.3(1), along with the location