An Analysis of the Physical Coastal System along East Coast Park, Singapore Daniel Martens 1203082-000 © Deltares, 2013, B Title An Analysis of the Physical Coastal System along East Coast Park, Singapore Client Project Pages EcoShape 1203082-000 136 Keywords Singapore, East Coast Park, coastal erosion, structurally controlled coast, headland control, conceptual model, temporal and spatial morphological scales, cross- and longshore sediment transport, waves, tide, monsoons, eustatic sea level rise, land subsidence Abstract The Republic of Singapore, or commonly referred to as Singapore, is the smallest nation in Southeast Asia and it is well protected from the open oceans by the surrounding land masses. Its total surface area has increased by more than 20% since the 1960s due to intensive land reclamations, for which the main reason was to create more accommodation space for the increasing population. Along the southeast coast of Singapore, some 1.85 km2 was reclaimed for recreational purposes, resulting in a 15 km long coastal park called East Coast Park. East Coast Park is built on entirely reclaimed land and comprises a sandy shoreline. The beaches along this shoreline are formed due to the implementation of anthropogenic structures all along this stretch of coast through so-called headland control. These structures were meant to stabilise the newly reclaimed land, which was placed on top of an unconsolidated thick layer of marine clay. In time, however, several phenomena have occurred along this new stretch of coast, indicating coastline retreat due to erosion and in some cases also flooding of the coastal area. Researchers of the EcoShape Consortium have therefore decided to investigate the possibility of applying the so-called Building with Nature principles in solutions to coastline retreat along East Coast Park, resulting in the East Coast Park design pilot. A key aspect in this investigation is the understanding of the underlying coastal processes, which has resulted in the study before you. In this study an analysis is made of knowledge to date and a conceptual model is developed to analyse coastal processes on both a small and a large scale. Driving forces underlying these processes are waves, the tide, monsoons and relative sea level rise. On the large scale the influence of waves, the tide and relative sea level rise on the coastal morphology is assessed (semi-)quantitatively using numerical modelling tools Delft3D, Unibest-TC and Unibest-LT, but also using nautical charts and satellite imagery. On this scale the presence of anthropogenic structures is neglected. On the small scale the presence of structures is included. Due to insufficiently readily available data the assessment is made more quantitatively, using satellite imagery and photographs. Version Date Author Initials Review Initials Approval Initials may 2013 D. Martens M.C.J.L. Jeuken T. Schilperoort State final An Analysis of the Physical Coastal System along East Coast Park, Singapore 14 May 2013, final AN ANALYSIS OF THE PHYSICAL COASTAL SYSTEM ALONG EAST COAST PARK, SINGAPORE by Daniel Martens A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in the field of Civil Engineering at Delft University of Technology Delft, The Netherlands Submitted for approval on May 14, 2013 An Analysis of the Physical Coastal System along East Coast Park, Singapore i 14 May 2013, final Graduation committee Prof.dr.ir. M.J.F. Stive Chairman, Delft University of Technology Dr. M.C.J.L. Jeuken Deltares / EcoShape Dr.ir. J.S.M. van Thiel de Vries Deltares / Delft University of Technology Dr.ir. G.J. de Boer Deltares / Delft University of Technology Dr. S.K. Ooi National University of Singapore / Singapore-Delft Water Alliance Dr. D.K. Raju National University of Singapore / Tropical Marine Science Institute An Analysis of the Physical Coastal System along East Coast Park, Singapore D. Martens / May 14, 2013 This research was carried out at: Deltares Rotterdamseweg 185 2600 MH Delft The Netherlands and Singapore-Delft Water Alliance (SDWA) EW1 02-05 2 Engineering Drive 2 Singapore 117577 Singapore Daniel Martens © 2013. All rights reserved. Reproduction or translation of any part of this work in any form by print, photocopy or any other means, without the prior permission of either the author, members of the graduation committee and/or Deltares is prohibited. ii An Analysis of the Physical Coastal System along East Coast Park, Singapore 14 May 2013, final January 19, 1822 At twelve o'clock to-day we passed the narrow channel of the Rabbit and Coney, the western entrance of the Straits of Singapore, and soon found ourselves surrounded in every direction by beautiful verdant islands. The sea was smooth, the sky clear, and the whole prospect equally novel and pleasing. From the deck there could be counted between fifty and sixty green and woody islands of various dimensions, and from the mast-head above seventy. I do not believe there is any part of the world which can afford a prospect, in its way, of superior beauty, and this indeed has been observed and confessed by all voyagers. The prospect we had on entering the Singapore coast was beautiful and unexpected. We found ourselves completely landlocked, in every direction, by the green and woody shores of the islands surrounding us; and the sea, though considerably ruffled without, was here as smooth as glass. John Crawfurd (1783 - 1868) From Journal of an Embassy from the Governor-General of India to the Courts of Siam and Cochin China, Vol. 1, 1830, page 64, dated 19 January 1822 An Analysis of the Physical Coastal System along East Coast Park, Singapore iii 14 May 2013, final Abstract The Republic of Singapore, or commonly referred to as Singapore, is the smallest nation in Southeast Asia and it is well protected from the open oceans by the surrounding land masses. Its total surface area has increased by more than 20% since the 1960s due to intensive land reclamations, for which the main reason was to create more accommodation space for the increasing population. Along the southeast coast of Singapore, some 1.85 km2 was reclaimed for recreational purposes, resulting in a 15 km long coastal park called East Coast Park. East Coast Park lies along the southeast coast of Singapore and it is characterised by a range of sandy beaches, which have been formed after to the implementation of anthropogenic structures all along this stretch of coast. These structures were meant to stabilise the newly reclaimed land, which consists of relatively coarse fill material on top of an unconsolidated thick layer of marine clay. In time, however, several phenomena have occurred along this new stretch of coast, indicating coastline retreat due to erosion and in some cases also flooding of the coastal area. Researchers of the EcoShape Consortium have therefore decided to investigate the possibility of applying the so-called Building with Nature principles in solutions to coastline retreat along East Coast Park, resulting in the East Coast Park design pilot. A key aspect in this investigation is the understanding of the underlying coastal processes, which has resulted in the study before you. Due to the fact that only limited data was readily available throughout this study, the (relative) influence of coastal processes has mainly been addressed qualitatively, but where possible quantitatively. In order to assess these processes two scales were analysed separately, namely (1) a (coastal) cell system scale, with a coastal cell being a beach enclosed by two adjacent anthropogenic structures, and (2) the ECP system scale, comprising all of the coast along East Coast Park. On these scales different processes contribute to changes in the coastal morphology. These processes are induced by different driving forces, of which we identified (a) waves, (b) tide, (c) monsoon-induced wave variability and (d) relative sea level rise. Looking at the large-scale system of East Coast Park, we mainly addressed the influence of relative sea level rise on the southeast coast of Singapore. Relative sea level rise consists of both local sea level rise and land subsidence. Local sea level rise is assumed to follow global projections of sea level rise, see also NCCS (2012). Land subsidence, however, is found to be of the same order of magnitude as eustatic sea level rise at the present day, resulting in a local relative sea level rise twice as large as the eustatic sea level rise. This has been observed through subsidence of both the land and anthropogenic structures along East Coast Park over the past decades. The effect of land subsidence decreases asymptotically in time, but due to the fact that East Coast Park is relatively young the effect is assumed to be still significant for the upcoming years to decades. From the analysis of the small-scale system of coastal cells it was found that the influence of waves is mainly felt in the cross-shore direction rather than the longshore direction. Waves contain too little energy to transport coarse sediments alongshore in deeper waters, but are able to cause alongshore drift along the waterline at the beach. This alongshore drift is shown to be varying in time, depending on the angle of wave incidence, which changes due to changing monsoons and wind directions throughout the year. In cross-shore direction sediment is lost due to wave action on the beach berm and beach profile, leading to the An Analysis of the Physical Coastal System along East Coast Park, Singapore v 14 May 2013, final formation of scarps along the beach planform. These results have been obtained using the numerical modelling tools Unibest-TC and Unibest-LT, satellite imagery, bathymetrical charts and photographs. For the influence of the tide on the coastal morphology use has been made of a nested Delft3D model, from which resulted that the influence of the tide is negligible in the nearshore region, since tidal currents pick up (fine) sediments only at a distance of about 200 m offshore.