Coastal Defence Report on the evolution of the Ribble Estuary, with particular reference to the north Sefton coast. Version 1.1 March 2008 Prepared by: Sefton Council Vanessa Holden Technical Services Natural, Geographical & Applied Sciences Balliol House Edge Hill University Balliol Road St Helens Road Bootle Ormskirk L20 3NJ Lancashire Tel: +44 (0)151 934 4238 L39 4QP Fax: +44 (0)151 934 4559 Email:[email protected] www.sefton.gov.uk Title Report on the evolution of the Ribble Estuary, with particular reference to the north Sefton coast. Creator/Author/ Originator/ Vanessa Holden Publisher Sefton Council Date of publication March 2008 Contact name or title of Location Coastal Defence, Sefton Council Subject - Keyword Estuary Keyword – Free text Southport, estuaries, Ribble Description/Abstract Within the last 200 years the Ribble Estuary has experienced considerable human intervention, particularly associated with engineering works and reclamation schemes, undertaken primarily to develop and maintain access to the former Port of Preston, to provide new land for agricultural and commercial uses, and to allow development of the town of Southport. Identifier Coverage - Spatial Ribble Estuary Coverage - Temporal 1800’s to 2008 Format/ Presentation type Document Digital Type Report Subject - Category Coast Subject - Project Language English Rights - Copyright O/S maps reproduced under licence number LA 076317 by Sefton Metropolitan Council from the Ordnance Survey’s 1:50,000 map with the permission of the controller of Her Majesty’s Stationary Office Crown Copyright reserved Rights - EIR disclosability indicator Rights - EIR exemption Rights - FOIA disclosability indicator Rights - FOIA exemption Postal address of location Ainsdale Discovery Centre, The Promenade, Shore Road, Ainsdale-on-Sea, Southport Postcode of location PR8 2QB Telephone number of location +44 (0)151 934 2960 Fax number of location +44(0)1704 575628 Email address of location [email protected] Online resource www.sefton.gov.uk Date of metadata update This report should be referenced as: Holden, V.J.C. (2008) Report on the evolution of the Ribble Estuary. Sefton Council, Bootle. Document History Date Release Notes March 2008 1.0 Final Report Prepared ____V. Holden________________ Approved ____________________________ Authorised ____________________________ Copyright Sefton Council Sefton Council accepts no liability for the use by third parties of results or methods presented in this report. Sefton Council also stresses that various sections of this report rely on data supplied by or drawn from third party sources. Sefton Council accepts no liability for loss or damage suffered by the client or third parties as a result of errors or inaccuracies in such third party data. Contents Section Page 1.0 Introduction 1 2.0 Background to the Sefton Coast 1 3.0 Secondary Data Available 1 3.1 Secondary Data Confidence 3 4.0 The Ribble Estuary 4 4.1 Human Impacts on the Estuary 6 4.1.1 Developments Relating to the Port of Preston 6 4.1.2. Land Reclamation in the Ribble Estuary 12 4.1.3 Other Developments 15 5.0 The Environmental Response of the Ribble Estuary 34 5.1 Pre-Industrialisation 34 5.2 Training of the Navigable Channel and its Implications 42 5.3 Sediment Accretion Along the Southern Estuary Foreshore 50 5.4 Changes in the Bog Hole Channel 57 6.0 Summary 67 7.0 References 68 Report on the Evolution of the Ribble Estuary 1. 0 Introduction This report is part of a series designed to give a detailed account of a particular feature on the Sefton Coast as part of the process of updating the Sefton Coast Database. Updating of the database includes analysis and interpretation of existing materials held by the Council which will identify gaps in knowledge and future works that could be undertaken to improve our understanding of the geomorphology of the Sefton Coast. This particular report discusses the evolution of the Ribble Estuary in North West England through time from the early 1800’s to the present day. By using various forms of secondary data, a picture of the development of the location can be built up, providing a basis for understanding the present day situation. 2.0 Background to the Sefton Coast The coast is a long wide arc of sand with a hindshore dune system, which at one time would have stretched from the Mersey Estuary to the Ribble Estuary. Human use of the dune system over several centuries has created a dune landscape of great variety. To the north of the Sefton Coast is an extensive area of Saltmarsh extending into the Ribble estuary; other smaller areas of Saltmarsh also occur at the River Alt and Smiths Slack (located on the foreshore between Birkdale and Ainsdale). Several towns have developed along the coast; at Crosby, to the south, and Southport, to the north, artificial defences have been put in place. In- between these areas towns such as Formby rely upon the sand dunes to provide protection from the sea. The sand dunes, beaches and marshes of the Sefton Coast are one of the most important areas for nature conservation in Europe. The entire Coast is designated as either Special Protection Area (SPA) to the north of the pier at Southport or Special Area of Conservation (SAC) to the south of the pier, notable species include Sand Lizards and Natterjack Toads with the estuarine area being very important for birds. The Sefton Coast is also an important visitor destination with popular bathing beaches, open countryside, and the seaside resort of Southport. 3.0 Secondary Data Available Much of the information regarding the estuary originates from the archives of the Borough Engineers, with a great deal of the literature around the time of the major engineering works being written by: • The Engineer and General Superintendent of the Ribble Navigation 1901-1933 (James Barron); 1 Report on the Evolution of the Ribble Estuary • Southport Borough Engineer, early 1900s (Mr A.E. Jackson); • Engineer for Preston Corporation, 1890 until 1900, and later consulting engineer to Mersey Estuary (Mr Alexander F. Fowler); • Ribble Engineer 1933 to mid 1900s (Mr A.H. Howarth, successor to James Barron); • Consulting engineers (Mr L.F. Vernon-Harcourt, early 1900s, and Commander F.W. Jarrad, 1907). It is for this reason that the evidence surrounding the development of the location is centred on the three main issues of navigation, reclamation, and the urban development of Southport. Similarly, there is significant emphasis on the development of the Bog Hole Channel, as this was an area of increasing concern during the first half of the twentieth century; hence issues around it were recorded in relative prevalence. Table 1.1 shows the main types of secondary data that are available and which were utilised to construct the picture of the evolution of the estuary. Data Type Format Date Range Aerial Photographs Digital and printed original 1945 to present Ordnance Survey Maps Digital and printed original 1843 to present Navigation & Bathymetric Digital and printed original 1736 to 1937 Charts Historic Photographs Digital and printed original c.1900 onwards Unpublished Reports / Original c.1880 onwards ‘Grey’ Literature Published Books Original 1888 onwards Vegetation Survey Data Original 1998 to present Profile Survey Data Digital 1913 to present Table 3.1: Type and format of secondary data sources available within the Sefton Coast Database. 2 Report on the Evolution of the Ribble Estuary 3.1 Secondary Data Confidence Historic accounts and data provide an invaluable record of the developments that have taken place along the coastline, without which, the significance and reasoning of many events would be lost, facts obscured, or simply forgotten. However, it is important to remember that most records are subject to the opinions and observations of the individuals making them, which can in some circumstances, give little indication of the accuracy of the data. The accuracy of early charts may be questionable, particularly as they would potentially have been drawn up for specific purposes, hence certain channels or features that were not considered by the surveyor to be important may have been recorded in much less detail, or even omitted. However, that said, as a certain level of accuracy would have been required for navigation purposes, the charts can be assumed to be representative of general episodes within the estuary. As the charts of Mackenzie, Belcher, Williams and Webb, and Calver (Section 5.1) were made and published by the Admiralty (Barron, 1938), so some degree of data confidence can be attributed to their provenance. Discrepancies between certain channel depths and low water marks may have potentially arisen between texts due to the variance between datums used for soundings. During the Nineteenth Century, the datums referred to are generally those of the ‘Old Dock Sill’ at Liverpool (from the first enclosed Liverpool Dock built in 1715 (Cashin, 1949)). From around 1844, Ordnance Datum referred to the mean sea level at Liverpool, which was 4.67 feet (1.42 m) above the Old Dock Sill. From around 1933, Ordnance Datum was based upon mean sea level at Newlyn, which was 14.54 feet (4.43 m) above the Old Dock Sill (Barron, 1938; Cashin, 1949; Gresswell, 1953). The level of the Old Dock Sill was believed to be 7ft. 9in. (2.36 m) above the level of Low Water at Southport (Jarrad, 1907), with the Ribble being calculated as 12.37 feet (3.77 m) below Ordnance Datum (Liverpool) in 1890 (Barron, 1938). Similarly, early Ordnance maps based the High and Low Water Marks around surveys taken at times when the Admiralty informed them that there were expected to be ‘ordinary’ tides, which when combined with weather conditions, may produce misleading levels on flat stretches of coastline such as in the Ribble Estuary (Barron, 1938).