This process is known as longshore drift. 1). Cooper, J. Andrew G. Erosion and Adaptation Project in West Africa Coastal Area: Inception Workshop October 19-21, 2016 Lom, Togo The coastal areas of West Africa is home to 31% of the West African population and produces 56% of the sub region's GDP. Cooper, J. Andrew G. It was driven by a series of eight large swell events (Hs 3 m) and several minor ones which struck over a period of four months (Fig. 2006 erosion episodes at Eastmoor Crescent, Durban. The March 2007 storm event was a severe storm that triggered the severe erosion of 350 km of the KwaZulu-Natal coastline. The KZN coast is also impacted by easterly to SE swells associated with tropical cyclones (hurricanes) and cut-off low (COL) storms. From this point to the end of August, chronic coastal erosion occurred at some EHS localities: Little Maritzburg Lane (Ballito), Eastmoor Crescent, (Durban), Inyoni Rocks (Durban), Submarine Bay, Clansthal, Scottburgh and Mzumbe. 2012. Nandasena, Aruna K. Ballito rocky coastline following the March 07 swell event. Figure 3. Data collection for this project is ongoing and results will be made available in due course. 9). It typically occurs due to a combination of the energy produced by waves, wind and ocean currents. Figure 4. comm. The most dramatic effects were associated with a large swell on the March equinox (18th20th), which had an 8.5 m significant shallow water wave height (Hs) and a maximum swell height of 14 m (Hmax) (M. Rossouw, CSIR, pers. In addition to protecting the coastline from erosion, coastal protection can also help stabilize shorelines. 2 beyond property damage, coastal erosion can bring about a variety of other economic Reference Smith, Guastella, Bundy and Mather2007). and These sea walls also protect your property from a wide range of harmful environmental impacts. Data from the March (2007) swell, measured at Durban. hasContentIssue true, Decaying cyclone swell erosion morphodynamics, Copyright Cambridge University Press 2010. The South African coastal environment is an important national asset and offers economic and social benefits. Besides flooding (a process of submerging of land that is usual dry by overflowing water), coastal communities must battle with other climate change induced challenges such as sea level rise, coastal erosion, ocean pollution, rising sea surface temperature, coral bleaching and severe droughts (IPCC, 2019 ). It is a type of tetrapod (structure). The natural coastline recovered (at least 60 %) within a year. These works are full-scale model tests, and have been proven to be effective in many situations. A continuous sand beach in the form of a 20 km long zeta bay extends through the Durban Bight (Fig. Recurrence interval estimates of the March 07 swell event range from 20 years (based on the historic record: Guastella et al. Feature Flags: { Botes, Z.A. Has data issue: true The Normalized Difference Vegetation and Water Index (NDVI) are two useful metrics that can be used to measure the erosion rate. 2007011, Marine Geosolutions (Pty) Ltd, 2008)(Fig. The July, 2007 image was captured prior to peak erosion; note the lack of surf bars. Box 320, Stellenbosch, 7599, South Africa, https://doi.org/10.1017/S0016756810000361, Reference Ruggiero, Komar, McDougal, Marra and Beach, Reference Sallenger, Krabill, Brock, Swift, Manizade and Stockdon, Reference Bromirski, Flick, Cayan and Graham, Reference Hemer, McInnes, Church, O'Grady and Hunter, Reference Smith, Guastella, Bundy and Mather, Reference Thornton, Humiston and Birkemeier, Reference Thornton, MacMahan and Sallenger, Reference Cooper, Jackson, Navas, McKenna and Malvarez, Reference Castelle, Le Corre and Tomlinson, Reference Guastella, Smith, Mather and Bundy, Reference Gratiot, Anthony, Gardel, Gaucherel, Proisy and Wells, Reference Oost, De Haas, Jensen, Van den Boogert and De Boer, Reference Bning, Dispert, Visbeck, Rintoul and Schwarzkopf, Extreme storms on the Pacific Northwest Coast during the 199798 El Nio and 199899 La Nia, Shoreface morphodynamics of a high-energy, steep and geologically constrained shoreline segment in Northern Ireland, The response of the Antarctic Circumpolar Current to recent climate change. Figure 7. and Ben Idun, a Ghanaian who opened a beach resort in Elmina in 2009, says the rapid erosion is partly due to illegal sand mining. Backstrom, Joni June 4, 2011 - Three major North African cities - Alexandria, Casablanca and Tunis - face losses of more than $1 billion each, over the next two decades, as risks of natural disasters intensify with the onset of climate change. Updates to the DE Africa Coastlines algorithms are in progress to improve the quality of the reference data and enable extraction of coastlines with great precision from the Landsat images. KZN is seeing a regional sand deficient, due to drought, sand mining, dam construction and unwise coastal development. Digital Earth Africas latest service release, is a monitoring tool that enables users to analyse coastal erosion and growth trends on an annual basis at local, regional and continental scales. During this time there were no large (> 3 m) swells (Fig. 1) deepened from 18.3 to 25.0 m CD between December 2005 and February 2006 (Table 4). For example, the effects of El Nio on storms have been noted in California (Ruggiero et al. Green, Andrew At its peak, winter erosion occurred during neap tides and even during low swells; however, the greatest impact was during high swells and spring tides. The largest swell (H s = 8.5 m) struck the coast on the March equinox (18th-20th) and generated a strong storm-return flow. As the rising swell limb was very steep, offshore sediment transport probably took place early in the March 07 swell event following a process of episodic net offshore bar migration (see Ruessink, Pape & Turner, 2008). 4). During subsequent smaller swell events, the lack of a nearshore bar system reduced the frictional effect of incoming swell and resulted in waves breaking closer to shore, with higher energies due to reduced energy dissipation. Box 1016, Ballito 4420, South Africa, Centre for Coastal and Marine Research, School of Environmental Sciences, University of Ulster, Cromore Road, Coleraine BT52 1SA, Northern Ireland, Bayworld Centre for Research & Education (BCRE), 5 Riesling Rd, Constantia 7806, South Africa, Marine Geosolutions, 105 Clark Rd, Glenwood, Durban, 4001, South Africa, Coast & Ocean Competency Area, CSIR, P.O. Until recently, South Africa had no legislation that dealt with at-risk infrastructure. The additional revenues estimated at industry level could also lead to the creation of 3,650 new direct jobs and around 7,000 indirect ones in Africa, resulting in $50 million and $95 million in salaries, respectively. Do not hesitate to look at our collection of knowledge base articles or ask question in our helpdesk. Coastal erosion is part of the natural coastal systems whereby coasts adjust to sediment availability and the ambient wave and tide conditions. All of these areas had wide sandy beaches at the time the March 07 swell hit, reducing the impact; this effect has been noted elsewhere (Sallenger et al. The aim of this paper is to document the impacts of the 20062007 Erosion Event on the KZN coast of South Africa (Fig. 6), especially within the 5 m amsl contour (5.9 m CD), and particularly where bedrock is shallow (Smith et al. Wave run-up inundation levels reached 11.6 m CD, but in general this did not result in scour, unless focused by badly placed infrastructure. Leuci, Rio In rocky coastal areas it was also noted that the wave-cut platform was only partially exposed, with part remaining buried under dune sand or drained swampland (Fig. Significant 20062007 swell events (Hso > 3 m) for the KwaZulu-Natal Bight area. The Coastal Managment Programme, published in 2015, noted that coastal erosion is occurring at "a number of points along the City's coastline as a direct result" of urban development. Figure 6. Leuci, Rio These benefits are estimated to be worth as much as 28% of the GDP. However, the actual life will vary based on the concrete mix and accelerated corrosion rates. Some relatively minor erosion took place, but the catastrophic destruction anticipated at Eastmoor Crescent, considering its recent history, did not take place. Weighing up to 80 tonnes (88 short tons ), dolosse are used to build revetments for . 1). Africas non-life insurance penetration rate is 1.8%, about half of the global average set at 3.3%. Further we would like to thank two anonymous referees for helpful comment which was used to improve this paper. This ongoing coastal erosion is attributed to various global and regional factors, including coastal and terrestrial land use changes, river sand mining and dam construction (Garland & Moleko, Reference Garland and Moleko2000). 2). The drivers of coastal erosion are complex and include large magnitude events (large swells, tsunamis and storms), sea level rise, sediment scarcity, human activities and antecedent conditions. and It also reduces the wave energy that reaches the coast. Ballito: multi-storey block founded on the dune cordon and located within the 5 m amsl contour. data, 2008: http://researchspace.csir.co.za/dspace/bitstream/10204/2561/1/Theron_2008.pdf). Moreover, it did not have the legal framework to protect its coastline. seaside resort of Saly Portudal in Mbour-Senegal. Green, Andrew N. "shouldUseShareProductTool": true, One of the most effective ways to protect riverbanks is to restore natural vegetation. According to climate change expert at Ghana's Ministry of Food and Agriculture Eric Twum, coastal erosion is a major challenge for countries across West Africa. However, seawalls stop the supply of sediment, which can cause erosion. 7). 2014. Beaches with, and adjacent to, inappropriate sea defences, Beaches where the built environment is located too close to the high-water mark, and. All rights reserved. During 2006-2007, the KwaZulu-Natal coast of South Africa was exposed to several large swell events (H o > 3 m), near the peak of the lunar nodal cycle, causing shoreline recess Gorongoza National Park, 1317 September, 1971, South African Regional Committee for the Conservation and Utilisation of Soil, 2006 erosion episodes at Eastmoor Crescent, Durban, Decaying cyclonic swells that preceded the March (2007) swell, Data from the March (2007) swell, measured at Durban. Between the swells on the 30th August (Ho = 3.2 m) and the 26th September equinox (Ho = 3.3 m), no major swell occurred and the nearshore (surf) bars were able to reform, restricting further erosion. Extrapolation from these measurements suggests that 2.5 107 m3 of sand could have been lost from the total KZN coast in 48 hours (Smith et al. The DE Africa team has been working with implementing partners to validate the coastline tool for West Africa initially, with the view to validate at the continental scale. Maintain and rehabilitate natural dune vegetation, this assists in stabilising the frontal dune which in turn will offer protection against storm surge and erosion. *EQ equinoxes (2006), LNC lunar nodal cycle (2006), MS March swell (2007) and WE winter erosion (2007).
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