Eastern CFRAM Study HA09 Hydraulics Report - DRAFT FINAL Eastern CFRAM Study HA09 Hydraulics Report – Kilcock Model DOCUMENT CONTROL SHEET Client OPW Project Title Eastern CFRAM Study Document Title IBE0600Rp0027_HA09 Hydraulics Report Model Name Kilcock Rev Status Author(s) Modeller Reviewed by Approved By Office of Origin Issue Date . D01 Draft K. Smart D. Irwin S. Patterson M. Brian Belfast 08/01/2014 D02 Draft T. Carberry D. Irwin S. Patterson G. Glasgow Belfast 27/06/2014 F01 Draft D. Irwin D. Irwin S. Patterson G. Glasgow Belfast 13/02/2015 Final F02 Draft D. Irwin D. Irwin S. Patterson G. Glasgow Belfast 13/08/2015 Final F03 Draft D. Irwin D. Irwin S. Patterson G. Glasgow Belfast 05/08/2016 Final IBE0600Rp0027 F03 Eastern CFRAM Study HA09 Hydraulics Report - DRAFT FINAL Table of Reference Reports Report Issue Date Report Reference Relevant Section Eastern CFRAM Study Flood Risk December IBE0600Rp0001_Flood Risk 3.5.9 Review 2011 Review_F02 Eastern CFRAM Study Inception August 2012 IBE0600Rp0008_HA09 Inception 4.3.2 Report UoM09 Report_F02 Eastern CFRAM Study Hydrology September IBE0600Rp0016_HA09_Hydrology 4.10 Report UoM09 2013 Report_F01 Eastern CFRAM Study HA09 Liffey November 2001s4884- SC2 Survey Report v1 1.2 Survey Contract Report 2012 Eastern CFRAM Study Overarching May 2013 IBE0600Rp0014_F02 4.2 Report on the October 2011 Flood IBE0600Rp0027 F03 Eastern CFRAM Study HA09 Hydraulics Report - DRAFT FINAL 4 HYDRAULIC MODEL DETAILS 4.15 KILCOCK MODEL 4.15.1 General Hydraulic Model Information (1) Introduction: The Eastern CFRAM Flood Risk Review (IBE0600Rp0016_Flood Risk Review) highlighted Kilcock as an AFA for fluvial flooding based on a review of historic flooding and the extents of flood risk determined during the PFRA. The Kilcock model encompasses the upper reaches of the Rye Water including the tributaries which affect the Kilcock AFA including the smaller tributary watercourses the Culcor, Balfeaghan and Dolanstown. The total contributing catchment area is approximately 60 km2. The model is gauged at the downstream boundary at Annes Bridge (09048 – EPA). The Kilcock model discharges flows at its downstream end to the Maynooth model. A catchment run-off (NAM) model has been developed of the gauged catchment and calibrated against the low to mid range continuous flow trace at the Annes Bridge gauging station using gauge adjusted radar based hourly rainfall sums for the catchment from 2001 to 2010. Using the adjusted radar based rainfall sums and observed rainfall sums from surrounding rain gauges a continuous flow trace was simulated for the period 1950 to 2010. An AMAX series was extracted from the continuous flow trace and 3 the simulated Qmed observed to be 17.0 m /s. Although the simulated Qmed value may be affected by any uncertainty in the observed flow record at the gauging station (through calibration of the NAM model) they are considered improved estimates of Qmed at the gauging stations due to the longer record length, the quality of the rainfall and catchment data and the availability of the flow records for calibration. All of the watercourses within this model have been designated as HPWs, and have been modelled as 1D- 2D using the MIKE suite of software. Channel markers have been located at the right and left banks of all cross sections. Flow within these markers is calculated by the 1D model component; however when the water level rises sufficiently to meet the bank markers flow can enter the 2D domain which represents the floodplain. (2) Model Reference: HA09_KILC5 (3) AFAs included in the model: Kilcock (4) Primary Watercourses / Water Bodies (including local names): Reach ID Name 09RYEW RYE WATER 09CULC CULCOR 09BALF BALFEAGHAN IBE0600Rp0027 4.15-1 F03 Eastern CFRAM Study HA09 Hydraulics Report - DRAFT FINAL 09DOLA DOLANSTOWN (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) 4.15.2 Hydraulic Model Schematisation (1) Map of Model Extents: IBE0600Rp0027 4.15-2 F03 Eastern CFRAM Study HA09 Hydraulics Report - DRAFT FINAL Figure 4.15.1: Kilcock Model Overview IBE0600Rp0027 4.15-3 F03 Eastern CFRAM Study HA09 Hydraulics Report - DRAFT FINAL Figure 4.15.2: Kilcock AFA Extent Figure 4.15.1 and Figure 4.15.2 illustrate the extent of the modelled catchment, river centre line, HEP locations and AFA extents as applicable. The catchment contains 4 Upstream Limit HEPs, 3 Trib HEPs and 1 Gauging Station HEP which acts as the downstream limit of the model. The catchment does not contain any Intermediate HEPs. IBE0600Rp0027 4.15-4 F03 Eastern CFRAM Study HA09 Hydraulics Report - DRAFT FINAL (2) x-y Coordinates of River (Upstream extent): Table 4.15.1: x-y Coordinates of River River Name x y 09RYEW RYE WATER 285313.5 242027 09CULC CULCOR 285998.5 243940.5 09BALF BALFEAGHAN 288320 242472 09DOLA DOLANSTOWN 289762 241222 (3) Total Modelled Watercourse Length: 17.7 km (approx.) (4) 1D Domain only Watercourse Length: 0 km (5) 1D-2D Domain 17.7 km Watercourse Length: (approx.) (6) 2D Domain Mesh Type / Resolution / Area: Rectangular / 5 metres / 54 km2 (7) 2D Domain Model Extent: IBE0600Rp0027 4.15-5 F03 Eastern CFRAM Study HA09 Hydraulics Report - DRAFT FINAL Figure 4.15.3: Model 2D Domain IBE0600Rp0027 4.15-6 F03 Eastern CFRAM Study HA09 Hydraulics Report - DRAFT FINAL Figure 4.15.3 illustrates the modelled extents and the general topography of the catchment. The spatial extent of the AFA boundary is outlined in black. The reach centre-lines are presented in light-blue which also represents the 1D modelled extent that is within the 2D area. Buildings are excluded from the mesh and therefore represented as red. Refer to Chapter 3 for details on representation of buildings in the model. Figure 4.15.4 shows an overview drawing of the model schematisation. Figure 4.15.5 to Figure 4.15.9 show detailed views. The overview diagram covers the model extents, showing the surveyed cross-section locations, AFA boundary and river centre line. It also shows the area covered by the 2D model domain. The detailed areas are provided where there is the most significant risk of flooding. These diagrams include the surveyed cross-section locations, AFA boundary and river centre. They also show the location of the critical structures as discussed in Section 4.15.3(1), along with the location and extent of the links between the 1D and 2D models. For clarity in viewing cross-section locations, the detail diagrams show the full extent of the surveyed cross-sections. Note that the 1D model considers only the cross-section between the 1D-2D links. Figure 4.15.4: Model Schematisation Overview IBE0600Rp0027 4.15-7 F03 Eastern CFRAM Study HA09 Hydraulics Report - DRAFT FINAL Figure 4.15.5: Detailed Area of Model Schematisation showing Critical Structures Figure 4.15.6: Detailed Area of Model Schematisation showing Critical Structures IBE0600Rp0027 4.15-8 F03 Eastern CFRAM Study HA09 Hydraulics Report - DRAFT FINAL Figure 4.15.7: Detailed Area of Model Schematisation showing Critical Structures Figure 4.15.8: Detailed Area of Model Schematisation showing Critical Structures IBE0600Rp0027 4.15-9 F03 Eastern CFRAM Study HA09 Hydraulics Report - DRAFT FINAL Figure 4.15.9: Detailed Area of Model Schematisation showing Critical Structures (8) Survey Information (a) Survey Folder Structure: First Level Folder Second Level Folder Third Level Folder Murphy_E09_M05_WP3_120607_09BALF GIS and Gloodplain Structure Register Photos Where: Kilcock Surveyed Cross Section Lines Murphy - Surveyor Name Ascii E09 - Eastern CFRAM Study Area, Drawings and PDFs Hydrometric Area 09 M05 - Model Number 05 Photos (Naming convention is in the WP3 - Work Package 3 format of Cross-Section 120607 - Date issued (30 August 2012) ID and orientation - 09BALF - River Reference upstream, downstream, left bank or right bank) (b) Survey Folder References: Reach ID Name File Ref. 09RYEW RYE WATER Murphy_E09_M05_WP3_120619_09RYEW_A Murphy_E09_M05_WP3_120607_09RYEW_B IBE0600Rp0027 4.15-10 F03 Eastern CFRAM Study HA09 Hydraulics Report - DRAFT FINAL Murphy_E09_M05_WP3_120607_09RYEW_C Murphy_E09_M04_WP3_130315_09RYEW_D Murphy_E09_M04_WP3_120619_09RYEW_E 09CULC CULCOR Murphy_E09_M05_WP3_120619_09CULC 09BALF BALFEAGHAN Murphy_E09_M05_WP3_120607_09BALF 09DOLA DOLANSTOWN Murphy_E09_M05_WP3_120629_09DOLA (9) Survey Issues: Initial attempts to calibrate the model to Anne's Bridge gauging station (09048) suggested an error in the survey of the weir crest at this gauge. The original survey data received for section 09RYEW00978W showed that the lowest point of the weir was at the right bank and had a crest level of 50.470mOD Malin. Photos of the structure at low flow, as shown in Figure 4.15.10, suggested it was a V-shaped structure and the records of EPA who operate the station state that the lowest point of the crest is 50.259mOD Malin. A request was therefore made to have this section re-surveyed, and revised data was delivered on 15/03/2013 which stated that the invert level of the weir crest was 50.206mOD Malin. This revised data was included in the final hydraulic model. Figure 4.15.10: Anne's Bridge gauging station at low flow The 2D domain was derived using 5m resolution LiDAR data as described in section 2.2.2, and no localised post-processing of this data was carried out. IBE0600Rp0027 4.15-11 F03 Eastern CFRAM Study HA09 Hydraulics Report - DRAFT FINAL 4.15.3 Hydraulic Model Construction (1) 1D Structures (in-channel along See Appendix A.1 modelled watercourses): Number of Bridges and Culverts: 28 Number of Weirs: 5 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. On the Rye Water, bridges 09RYEW01608D (Balfeaghan Bridge), 09RYEW01469D (Meath Bridge) and 09RYEW00990D (Moyglare Road Bridge) restrict flow on the Rye Water and cause widespread flooding from both banks during design runs of 10% AEP or greater.