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Management of Coastal Erosion by Creating Large-Scale and Small-Scale Sediment Cells
COASTAL EROSION CONTROL BASED ON THE CONCEPT OF SEDIMENT CELLS by L. C. van Rijn, www.leovanrijn-sediment.com, March 2013 1. Introduction Nearly all coastal states have to deal with the problem of coastal erosion. Coastal erosion and accretion has always existed and these processes have contributed to the shaping of the present coastlines. However, coastal erosion now is largely intensified due to human activities. Presently, the total coastal area (including houses and buildings) lost in Europe due to marine erosion is estimated to be about 15 km2 per year. The annual cost of mitigation measures is estimated to be about 3 billion euros per year (EUROSION Study, European Commission, 2004), which is not acceptable. Although engineering projects are aimed at solving the erosion problems, it has long been known that these projects can also contribute to creating problems at other nearby locations (side effects). Dramatic examples of side effects are presented by Douglas et al. (The amount of sand removed from America’s beaches by engineering works, Coastal Sediments, 2003), who state that about 1 billion m3 (109 m3) of sand are removed from the beaches of America by engineering works during the past century. The EUROSION study (2004) recommends to deal with coastal erosion by restoring the overall sediment balance on the scale of coastal cells, which are defined as coastal compartments containing the complete cycle of erosion, deposition, sediment sources and sinks and the transport paths involved. Each cell should have sufficient sediment reservoirs (sources of sediment) in the form of buffer zones between the land and the sea and sediment stocks in the nearshore and offshore coastal zones to compensate by natural or artificial processes (nourishment) for sea level rise effects and human-induced erosional effects leading to an overall favourable sediment status. -
GEOTEXTILE TUBE and GABION ARMOURED SEAWALL for COASTAL PROTECTION an ALTERNATIVE by S Sherlin Prem Nishold1, Ranganathan Sundaravadivelu 2*, Nilanjan Saha3
PIANC-World Congress Panama City, Panama 2018 GEOTEXTILE TUBE AND GABION ARMOURED SEAWALL FOR COASTAL PROTECTION AN ALTERNATIVE by S Sherlin Prem Nishold1, Ranganathan Sundaravadivelu 2*, Nilanjan Saha3 ABSTRACT The present study deals with a site-specific innovative solution executed in the northeast coastline of Odisha in India. The retarded embankment which had been maintained yearly by traditional means of ‘bullah piling’ and sandbags, proved ineffective and got washed away for a stretch of 350 meters in 2011. About the site condition, it is required to design an efficient coastal protection system prevailing to a low soil bearing capacity and continuously exposed to tides and waves. The erosion of existing embankment at Pentha ( Odisha ) has necessitated the construction of a retarded embankment. Conventional hard engineered materials for coastal protection are more expensive since they are not readily available near to the site. Moreover, they have not been found suitable for prevailing in in-situ marine environment and soil condition. Geosynthetics are innovative solutions for coastal erosion and protection are cheap, quickly installable when compared to other materials and methods. Therefore, a geotextile tube seawall was designed and built for a length of 505 m as soft coastal protection structure. A scaled model (1:10) study of geotextile tube configurations with and without gabion box structure is examined for the better understanding of hydrodynamic characteristics for such configurations. The scaled model in the mentioned configuration was constructed using woven geotextile fabric as geo tubes. The gabion box was made up of eco-friendly polypropylene tar-coated rope and consists of small rubble stones which increase the porosity when compared to the conventional monolithic rubble mound. -
Linktm Gabions and Mattresses Design Booklet
LinkTM Gabions and Mattresses Design Booklet www.globalsynthetics.com.au Australian Company - Global Expertise Contents 1. Introduction to Link Gabions and Mattresses ................................................... 1 1.1 Brief history ...............................................................................................................................1 1.2 Applications ..............................................................................................................................1 1.3 Features of woven mesh Link Gabion and Mattress structures ...............................................2 1.4 Product characteristics of Link Gabions and Mattresses .........................................................2 2. Link Gabions and Mattresses .............................................................................. 4 2.1 Types of Link Gabions and Mattresses .....................................................................................4 2.2 General specification for Link Gabions, Link Mattresses and Link netting...............................4 2.3 Standard sizes of Link Gabions, Mattresses and Netting ........................................................6 2.4 Durability of Link Gabions, Link Mattresses and Link Netting ..................................................7 2.5 Geotextile filter specification ....................................................................................................7 2.6 Rock infill specification .............................................................................................................8 -
GEOTEXTILE TUBE and GABION ARMOURED SEAWALL for COASTAL PROTECTION an ALTERNATIVE by S Sherlin Prem Nishold1, Ranganathan Sundaravadivelu 2*, Nilanjan Saha3
PIANC-World Congress Panama City, Panama 2018 GEOTEXTILE TUBE AND GABION ARMOURED SEAWALL FOR COASTAL PROTECTION AN ALTERNATIVE by S Sherlin Prem Nishold1, Ranganathan Sundaravadivelu 2*, Nilanjan Saha3 ABSTRACT The present study deals with a site-specific innovative solution executed in the northeast coastline of Odisha in India. The retarded embankment which had been maintained yearly by traditional means of ‘bullah piling’ and sandbags, proved ineffective and got washed away for a stretch of 350 meters in 2011. About the site condition, it is required to design an efficient coastal protection system prevailing to a low soil bearing capacity and continuously exposed to tides and waves. The erosion of existing embankment at Pentha ( Odisha ) has necessitated the construction of a retarded embankment. Conventional hard engineered materials for coastal protection are more expensive since they are not readily available near to the site. Moreover, they have not been found suitable for prevailing in in-situ marine environment and soil condition. Geosynthetics are innovative solutions for coastal erosion and protection are cheap, quickly installable when compared to other materials and methods. Therefore, a geotextile tube seawall was designed and built for a length of 505 m as soft coastal protection structure. A scaled model (1:10) study of geotextile tube configurations with and without gabion box structure is examined for the better understanding of hydrodynamic characteristics for such configurations. The scaled model in the mentioned configuration was constructed using woven geotextile fabric as geo tubes. The gabion box was made up of eco-friendly polypropylene tar-coated rope and consists of small rubble stones which increase the porosity when compared to the conventional monolithic rubble mound. -
Chapter 213 the Impacts of Shoreline Protection
CHAPTER 213 THE IMPACTS OF SHORELINE PROTECTION STRUCTURES ON BEACHES ALONG MONTEREY BAY, CALB^ORNIA GaryB. Griggs* James F. Tait* Katherine Scott* Abstract As a result of severe coastal storm damage in recent years along the California coast and the continuation of development and redevelopment in hazard prone oceanfront areas, large numbers of coastal protection structures have been built. This same trend has been observed on the Atlantic and Gulf coasts as well. At present, fully 12%, or 130 miles of California's 1100 miles of shoreline have been armored. As the number of structures and their coastal frontage has increased, concern along the California coast and elsewhere has arisen in regard to the impacts of these protective structures on the adjacent beaches. Three Atlantic coast states (Maine, New Jersey, and North Carolina) have responded to this concern by establishing state-level policy which prohibits construction of any new "hard" protective structures. Although considerable laboratory scale research has been carried out on this problem, field work has been extremely limited. A study along the central California coast was initiated in order to resolve some of the most critical questions regarding the impacts of protection structures on beaches. Based on 4 years of precise, biweekly, shore- based surveys in the vicinity of different types of seawalls along the shoreline of northern Monterey Bay along the central California coast, some consistent beach changes have been documented. All of the changes observed to date have been seasonal and are best developed in the fall and winter months during the transition from summer swell to winter storm conditions. -
1 the Influence of Groyne Fields and Other Hard Defences on the Shoreline Configuration
1 The Influence of Groyne Fields and Other Hard Defences on the Shoreline Configuration 2 of Soft Cliff Coastlines 3 4 Sally Brown1*, Max Barton1, Robert J Nicholls1 5 6 1. Faculty of Engineering and the Environment, University of Southampton, 7 University Road, Highfield, Southampton, UK. S017 1BJ. 8 9 * Sally Brown ([email protected], Telephone: +44(0)2380 594796). 10 11 Abstract: Building defences, such as groynes, on eroding soft cliff coastlines alters the 12 sediment budget, changing the shoreline configuration adjacent to defences. On the 13 down-drift side, the coastline is set-back. This is often believed to be caused by increased 14 erosion via the ‘terminal groyne effect’, resulting in rapid land loss. This paper examines 15 whether the terminal groyne effect always occurs down-drift post defence construction 16 (i.e. whether or not the retreat rate increases down-drift) through case study analysis. 17 18 Nine cases were analysed at Holderness and Christchurch Bay, England. Seven out of 19 nine sites experienced an increase in down-drift retreat rates. For the two remaining sites, 20 retreat rates remained constant after construction, probably as a sediment deficit already 21 existed prior to construction or as sediment movement was restricted further down-drift. 22 For these two sites, a set-back still evolved, leading to the erroneous perception that a 23 terminal groyne effect had developed. Additionally, seven of the nine sites developed a 24 set back up-drift of the initial groyne, leading to the defended sections of coast acting as 1 25 a hard headland, inhabiting long-shore drift. -
Guidance for Flood Risk Analysis and Mapping
Guidance for Flood Risk Analysis and Mapping Coastal Notations, Acronyms, and Glossary of Terms May 2016 Requirements for the Federal Emergency Management Agency (FEMA) Risk Mapping, Assessment, and Planning (Risk MAP) Program are specified separately by statute, regulation, or FEMA policy (primarily the Standards for Flood Risk Analysis and Mapping). This document provides guidance to support the requirements and recommends approaches for effective and efficient implementation. Alternate approaches that comply with all requirements are acceptable. For more information, please visit the FEMA Guidelines and Standards for Flood Risk Analysis and Mapping webpage (www.fema.gov/guidelines-and-standards-flood-risk-analysis-and- mapping). Copies of the Standards for Flood Risk Analysis and Mapping policy, related guidance, technical references, and other information about the guidelines and standards development process are all available here. You can also search directly by document title at www.fema.gov/library. Coastal Notation, Acronyms, and Glossary of Terms May 2016 Guidance Document 66 Page i Document History Affected Section or Date Description Subsection Initial version of new transformed guidance. The content was derived from the Guidelines and Specifications for Flood Hazard Mapping Partners, Procedure Memoranda, First Publication May 2016 and/or Operating Guidance documents. It has been reorganized and is being published separately from the standards. Coastal Notation, Acronyms, and Glossary of Terms May 2016 Guidance Document 66 -
Geotechnical Aspects of Seawall Stability with Climate Change
GEOTECHNICAL ASPECTS OF SEAWALL STABILITY WITH CLIMATE CHANGE Lex Nielsen WorleyParsons [email protected] Agustria Salim Pells Sullivan Meynink Doug Lord Coastal Environment Geoff Withycombe Sydney Coastal Councils Group Ian Armstrong Sydney Coastal Councils Group Introduction Existing seawalls and protection structures exist at many locations around the Australian coast where construction details are unknown and the capacity of the structures to withstand storms has not been verified. Seawall asset owners and managers (usually Local Councils) are faced with determining development applications in areas protected by such structures. Often, the responsibility, ownership and liability arising from these structures are not clear, with many structures constructed entirely or in part on Public Land. Frequently, there is conflict between the coastal managers and the community who have varying impressions of their effectiveness in providing protection and their impact on the public beach. This project has developed methods whereby the efficacy of existing seawalls may be determined. The project was undertaken by the Sydney Coastal Councils Group (SCCG) with funding provided by the Commonwealth Department of Climate Change and Energy Efficiency (DCCEE) through a Climate Adaptation Pathways (CAP) grant. The project was overseen by a National Reference Group comprising expertise from local government, state government, universities with coastal management expertise and industry specialists. Key elements of the project were as follows: Literature review of existing seawall types, remote sensing techniques, options for upgrading, certification requirements - Water Research Laboratory (WRL), University of NSW (UNSW). Geotechnical assessment of structure types and common failure modes - WorleyParsons. Economic aspects of the decision making process - Bond University under the direction of the Centre for Coastal Management (CCM) at Griffith University (GU). -
Harbor Protection Through Construction of Artificial Submerged Reefs
Harbor Protection through Construction of Artificial Submerged Reefs Amarjit Singh, Vallam Sundar, Enrique Alvarez, Roberto Porro, Michael Foley (www.hawaii.gov) 2 Outline • Background of Artificial Reefs • Multi-Purpose Artificial Submerged Reefs (MPASRs) ▫ Coastline Protection ▫ Harbor Protection • MPASR Concept for Kahului Harbor, Maui ▫ Situation ▫ Proposed Solution • Summary 3 Background First documented First specifically Artificial reefs in First artificial reef Artificial reefs in artificial reefs in designed artificial Hawaii– concrete/tire in Hawaii Hawaii – concrete Z- U.S. reefs in U.S. modules modules 1830’s 1961 1970’s 1985-1991 1991- Present • Uses • Materials ▫ Create Marine Habitat ▫ Rocks; Shells ▫ Enhance Fishing ▫ Trees ▫ Recreational Diving Sites ▫ Concrete Debris ▫ Surfing Enhancement ▫ Ships; Car bodies ▫ Coastal Protection ▫ Designed concrete modules ▫ Geosynthetic Materials 4 Multi-Purpose Artificial Submerged Reefs (MPASRs) Specifically designed artificial reef which can provide: • Coastline Protection or Harbor Protection ▫ Can help restore natural beach dynamics by preventing erosion ▫ Can reduce wave energy transmitted to harbor entrances • Marine Habitat Enhancement ▫ Can provide environment for coral growth and habitat fish and other marine species. ▫ Coral can be transplanted to initiate/accelerate coral growth • Recreational Uses ▫ Surfing enhancement: can provide surfable breaking waves where none exist ▫ Diving/Snorkeling: can provide site for recreational diving and snorkeling 5 MPASRs as Coastal Protection Wave Transmission: MPASRs can reduce wave energy transmitted to shoreline. Kt = Ht/Hi K = H /H t t i Breakwater K = wave transmission t Seabed coefficient, (Pilarczyk 2003) Ht= transmitted wave height shoreward of structure Hi = incident wave height seaward of structure. 6 MPASRs as Coastal Protection • Wave Refraction: MPASR causes wave refraction around the reef, focusing wave energy in a different direction. -
Mathematical Model of Groynes on Shingle Beaches
HR Wallingford Mathematical Model of Groynes on Shingle Beaches A H Brampton BSc PhD D G Goldberg BA Report SR 276 November 1991 Address:Hydraulics Research Ltd, wallingford,oxfordshire oxl0 gBA,United Kingdom. Telephone:0491 35381 Intemarional + 44 49135381 relex: g4gsszHRSwALG. Facstunile:049132233Intemarional + M 49132233 Registeredin EngtandNo. 1622174 This report describes an investigation carried out by HR Wallingford under contract CSA 1437, 'rMathematical- Model of Groynes on Shingle Beaches", funded by the Ministry of Agri-culture, Fisheries and Food. The departmental nominated. officer for this contract was Mr A J Allison. The company's nominated. project officer was Dr S W Huntington. This report is published on behalf of the Ministry of Agriculture, Fisheries and Food, but the opinions e>rpressed are not necessarily those of the Ministry. @ Crown Copyright 1991 Published by permission of the Controller of Her Majesty's Stationery Office Mathematical model of groSmes on shingle beaches A H Brampton BSc PhD D G Goldberg BA Report SR 276 November 1991 ABSTRACT This report describes the development of a mathematical model of a shingle beach with gro5mes. The development of the beach plan shape is calculated given infornation on its initial position and information on wave conditions just offshore. Different groyne profiles and spacings can be specified, so that alternative gro5me systems can be investigated. Ttre model includes a method for dealing with varying water levels as the result of tidal rise and fall. CONTENTS Page 1. INTRODUCTION I 2. SCOPEOF THE UODEL 3 2.t Model resolution and input conditions 3 2.2 Sediment transport mechanisms 6 2.3 Vertical distribution of sediment transport q 2.4 Wave transformation modelling L0 3. -
Storms and Coastal Defences at Chiswell This Booklet Provides Information About
storms and coastal defences at chiswell this booklet provides information about: • How Chesil Beach and the Fleet Lagoon formed and how it has What is this changed over the last 100 years • Why coastal defences were built at Chiswell and how they work • The causes and impacts of the worst storms in a generation booklet that occurred over the winter 2013 / 14 • What will happen in the future Chesil Beach has considerable scientific about? significance and has been widely studied. The sheer size of the beach and the varying size and shape of the beach material are just some of the reasons why this beach is of worldwide interest and importance. Chesil Beach is an 18 mile long shingle bank that stretches north-west from Portland to West Bay. It is mostly made up of chert and flint pebbles that vary in size along the beach with the larger, smoother pebbles towards the Portland end. The range of shapes and sizes is thought to be a result of the natural sorting process of the sea. The southern part of the beach towards Portland shelves steeply into the sea and continues below sea level, only levelling off at 18m depth. It is slightly shallower at the western end where it levels off at a depth of 11m. This is mirrored above sea level where typically the shingle ridge is 13m high at Portland and 4m high at West Bay. For 8 miles Chesil Beach is separated from the land by the Fleet lagoon - a shallow stretch of water up to 5m deep. -
Shoreline Stabilisation
Section 5 SHORELINE STABILISATION 5.1 Overview of Options Options for handling beach erosion along the western segment of Shelley Beach include: • Do Nothing – which implies letting nature take its course; • Beach Nourishment – place or pump sand on the beach to restore a beach; • Wave Dissipating Seawall – construct a wave dissipating seawall in front of or in lieu of the vertical wall so that wave energy is absorbed and complete protection is provided to the boatsheds and bathing boxes behind the wall for a 50 year planning period; • Groyne – construct a groyne, somewhere to the east of Campbells Road to prevent sand from the western part of Shelley Beach being lost to the eastern part of Shelley Beach; • Offshore Breakwater – construct a breakwater parallel to the shoreline and seaward of the existing jetties to dissipate wave energy before it reaches the beach; and • Combinations of the above. 5.2 Do Nothing There is no reason to believe that the erosion process that has occurred over at least the last 50 years, at the western end of Shelley Beach, will diminish. If the water depth over the nearshore bank has deepened, as it appears visually from aerial photographs, the wave heights and erosive forces may in fact increase. Therefore “Do Nothing” implies that erosion will continue, more structures will be threatened and ultimately damaged, and the timber vertical wall become undermined and fail, exposing the structures behind the wall to wave forces. The cliffs behind the wall will be subjected to wave forces and will be undermined if they are not founded on solid rock.