Technical Report 3/03 Morphology Desk Study
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TECHNICAL REPORT 3/03 MORPHOLOGY DESK STUDY Report No. B4027/TR03/03 Halton Borough Council Rutland House October 2004 Halton Lea Runcorn WA7 2GW NEW MERSEY CROSSING MORPHOLOGY DESK STUDY NEW MERSEY CROSSING MORPHOLOGY DESK STUDY CONTROLLED DOCUMENT Gifford and Partners Document No: B4027/TR03/03 Status: FINAL Copy No: Name Signature Date Prepared by: Andrew Brookes/Andrew A Brookes, A 07/10/04 Chalmers/Sally German/ABPmer Chalmers, S German, N Pontee Checked: Anthony Guay A Guay 07/10/04 Technical Approval: Paul Hillman P Hillman 07/10/04 Gifford Approved: Ian Hunt I Hunt 13/10/04 Revision Record Rev. Date By Summary of Changes Chkd Aprvd Halton Borough Council Gifford and Partners Rutland House 20 Nicholas Street Halton Lea Chester Runcorn CH1 2NX WA7 2GW NEW MERSEY CROSSING MORPHOLOGY DESK STUDY C O N T E N T S Page FOREWORD ...........................................................................................................................1 EXECUTIVE SUMMARY ........................................................................................................3 1. INTRODUCTION ...........................................................................................................5 2. ESTUARY CHARACTERISTICS..................................................................................6 2.1 General Setting....................................................................................................6 2.2 Palaeohydrological Context.................................................................................6 2.3 Estuary Form .......................................................................................................7 2.4 Tides ..................................................................................................................10 2.5 Surges................................................................................................................13 2.6 Tidal bore ...........................................................................................................13 2.7 Fresh Water Flow...............................................................................................13 2.8 Mixing.................................................................................................................14 2.9 Wind and Wave Climate ....................................................................................14 2.10 Sediment Sources..............................................................................................14 2.11 Anthropogenic Influences ..................................................................................15 3. HISTORICAL DATA SOURCES.................................................................................19 3.1 Bathymetric surveys ..........................................................................................19 3.2 EMPHASYS Data ..............................................................................................20 3.3 Aerial photographs.............................................................................................20 3.4 Additional secondary sources............................................................................22 4. ANALYSIS OF CHANGE............................................................................................23 4.1 Cross-sectional changes ...................................................................................23 4.2 Changes in volume ............................................................................................26 4.3 Channel change.................................................................................................31 4.4 Saltmarsh change..............................................................................................36 5. DISCUSSION OF CHANGE........................................................................................41 5.1 Background to physical parameters controlling change within an estuarine system................................................................................................41 5.2 Specific reasons for changes to the sediment regime in the Mersey ...............44 New Mersey Crossing New Mersey Crossing Gifford and Partners Morphology Desk Study Morphology Desk Study Page i Report No. B4027/TR03/03 6. CONCLUSIONS ..........................................................................................................46 7. REFERENCES ............................................................................................................48 APPENDICES Appendix A Channel Positions Appendix B Emphasys Database Channel Configuration Appendix C Aerial Photographs Appendix D List of Technical Reports New Mersey Crossing Gifford and Partners Morphology Desk Study Page ii Report No. B4027/TR03/03 FOREWORD Halton Borough Council, on behalf of the Mersey Crossing Group, is currently promoting a second integrated crossing of the Mersey within the Borough, between Runcorn and Widnes. Gifford and Partners were appointed as Project Manager and Lead Consultant in July 2001 to undertake the further studies necessary to take the project forward. A substantial body of work has been undertaken to date on the project, including design, investigation of funding options and environmental studies. The work has culminated in the production of a series of reports, which are summarised in the following table: Report Number & Report Title Principal Author Purpose of Report Status General Reports B4027/01 Report of Works 1 – Preliminary Gifford and Partners Report to the client on the Issued November Sources Survey desk study 2001 B4027/01 Report of Works 1 – Preliminary Gifford and Partners Report to the client on the Addendum No 1 Sources Survey – Addendum No desk study for Route 4 Issued November 1 – Fiddler’s Ferry Route 2001 B4027/02 Report of Works 2 – Volume 1 Gifford and Partners Report to the client on the Issued March 2003 studies carried out on alternative route options Report of Works 2 – Volume 2 Gifford and Partners Structure and Highways Drawings for ROW2 B4027/03 Route Selection Gifford and Partners Report to DfT to clarify Route Issued March 2004 selection B4027/04 Amendments to Technical Gifford and Partners Report to DfT summarising In preparation – due Reports changes to Technical Reports to be issued since MSA submission in July November 2004 2003 Environmental Impact Assessment for Options Appraisal & MSA B4027/EIA/01 Environmental Impact Gifford and Partners Scoping of impacts for EIA for Issued March 2002 Assessment Scoping Report consultation B4027/EIA/02 Environmental Impact Gifford and Partners Addendum to scoping report Issued August 2002 Assessment Scoping Report taking into account comments Addendum received from consultees B4027/EIA/03 Environmental Impact Gifford and Partners Report on EIA progress to Issued July 2003 Assessment Progress Report inform the ROW2 and for consultees B4027/EIA/04 Environmental Impact Gifford and Partners Statistical analysis of impacts Issued March 2003 Assessment Synthesis – Multi- to assist in decision making Criteria Analysis process B4027/EIA/05 Environmental Impact Gifford and Partners Report on changes to EIA as a In preparation – due Assessment Supplementary result of changes to the to be issued Report for the Major Scheme scheme since the submission November 2004 Appraisal of the MSA in July 2003 Environmental Impact Assessment for Orders and Applications B4027/EIA/05 Environmental Impact Gifford and Partners EIA Scoping Report for “The In preparation – due Assessment Orders and Scheme” detailing EIA to be to be issued Applications Scoping Report carried out for the November 2004 Environmental Statement Major Scheme Appraisal B4027/MSA/01 Appendix 1 Major Scheme Gifford and Partners Report submitted to DfT with Issued July 2003 Appraisal for New Mersey application for funding (Will be superseded Crossing – Volume 1 by B4027/MSA/02) Appendix 1 Major Scheme Gifford and Partners Worksheets in support of Appraisal for New Mersey above Crossing – Volume 2 B4027/MSA/02 Major Scheme Appraisal for New Gifford and Partners Report submitted to DfT with In preparation – due Mersey Crossing – Volume 1 application for funding to be issued Major Scheme Appraisal for New Gifford and Partners Worksheets in support of November 2004 Mersey Crossing – Volume 2 above New Mersey Crossing Gifford and Partners Morphology Desk Study Page 1 Report No. B4027/TR03/03 In addition to these main reports, the detailed technical studies have been reported in a series of Technical Reports which provide supporting details for the Report of Works, Environmental Impact Assessment and Major Scheme Appraisal. These reports are listed in Appendix D. The work undertaken to March 2003 focused on comparing potential options for a new crossing. In March 2003, Halton Borough Council and the Mersey Crossing Group voted unanimously for a preferred route upstream of the existing Silver Jubilee Bridge. A Major Scheme Appraisal (MSA) for the preferred scheme was submitted to the Department for Transport (DfT) in July 2003 with Halton Borough Council’s Local Transport Plan APR to apply for Central Government funding. In December 2003, the DfT responded by awarding the scheme “Super Work in Progress” status and requesting further information on the following issues: • Traffic impact over the wider road network • Hydrodynamic modelling • Economic Impacts • Statutory Procedures and Procurement • Funding Options – consideration of tolling as a means to fund the new crossing A second MSA