This study focuses on the impacts of SLR on coastal dunes and a protected tree species, Mimusops caffra, commonly known as coastal red milkweed, that occurs naturally in a patch of coastal forest in the eThekwini Municipality. Thanks to the staff of the Department of Environmental Planning and Climate Protection and the Department of Coastal Policy from eThekwini Municipality for their willingness to share their knowledge.
Climate change and sea level rise
Natural ecosystems in the borders of coastal cities and environments have been abused for many years and in several cases completely destroyed (Oppenheimer et al. 2019). In the Jamaica Bay/Rockaway sector of New York, for example, wetlands and sandy beaches protect nearby residential communities (Oppenheimer et al. 2019).
Aim and objectives
Study Area
Rocks in the Ecca Group, in particular, have been extensively affected by dolerites (Bell and Maud 2000). The topography of the EMA varies from steep slopes/escarpments in the west to a fairly gently sloping coastal plain moving eastward (McDonald et al. 2004).
Outline of dissertation
Introduction
Sea level rise projections
In addition, the Antarctic ice sheet is estimated to contribute between 2.3 and 5.4 m for RCP8.5 to sea level after 2100. A recent regional sea level analysis showed that there is an inconsistency in the rate of sea level change in the southern Africa with almost all tide gauges showing a rise of 3.6 mm per year except Zanzibar (Mather and Stretch 2012).
Risk and vulnerability along the eThekwini Municipality coastline
However, coastlines with a lack of sand supply are highly susceptible to severe erosion (Theron et al. 2008). Furthermore, rainfall is projected to decrease in parts of KZN as a result of climate change (Theron et al. 2008).
Climate change adaptation and resilience
Most adaptation responses to coastal impacts and risks that have been applied worldwide take a reactive approach to actual coastal risks or experienced disasters (Oppenheimer et al. 2019). The two main financial approaches used are the total economic value method and the valuation of ecosystem services (Abram et al. 2019).
Classification/characteristics of coastal ecosystems along the eThekwini
These areas are classified as: crucial biodiversity areas, conservation areas and part of the Durban Metropolitan Open Space System (D'MOSS) (Rouget et al. 2016). Land owned by the state consists of almost 9175 hectares which is 4% of the municipal area (Rouget et al. 2016).
Risk assessment of coastal ecosystems
A study by Harris et al. 2019) developed a theoretical context for delineating the types of ecosystem within the coastal zone to assist in conservation planning and assessment that is of global relevance. A conventional framework on coastal geoindicators for sandy coastal environments was undertaken (Carapuço et al. 2016).
Prior studies of dune and beach rehabilitation along the EM coastline
The indicators address key issues related to coastal protection and risk assessment, thus highlighting the importance of coastal indicators in delivering valuable information for coastal management (Carapuço et al. 2016). Beach nourishment and seawalls consisting of geotextile sandbags are the preferred soft engineering methods to be implemented along with coastal setback lines for protection along the EM shoreline (Corbella and Stretch 2012b).
Legislation on coastal zone management
In the National Climate Change Response White Paper, target B.4 states that the state is the legal custodian responsible for all coastal assets on behalf of South Africans (Freedman 2006). South Africa is a signatory to the Paris Agreement and has a number of Nationally Determined Contributions to contribute to the global response to climate change. The South African government will continue to play an important role in the ongoing discussions to further support and improve the international response to the climate change crisis (Parramon-Gurney and Gilder 2012).
Governance and Institutions
Durban is recognized as one of the leaders in climate change adaptation to date (Niekerk 2013). For example, the New York Panel on Climate Change (NPCC), established by the City of New York, provides the city with regular updates on climate information (Solecki et al. 2021). Scientists need to quickly interpret and co-produce data and results, while legislators and practitioners need to act now, but also look at the challenge of climate change from a long-term perspective (Solecki et al. 2021).
Responding to sea level rise
This also introduces the need for coordinated governance across all governance spheres and policy areas (Oppenheimer et al. 2019). Another challenge related to governance is to guarantee the effective maintenance of coastal protection (Oppenheimer et al. 2019). The City of Cape Town focuses on coastal climate change adaptation efforts to SLR and coastal flooding (Abram et al. 2019).
Conclusion
Therefore, governance needs to be included when making decisions about how to respond to SLR to resolve social conflicts and reach mutual agreements between all stakeholders (both public and private) when opportunities are presented.
Introduction
Research Methodology
- Literature survey
- Consultations
- Identifying and mapping high risk areas to sea level rise
- Risk assessment of sea level rise impacts on coastal ecosystem
A second assessment of the produced maps was carried out focusing only on sections/areas along the coast that are in the high risk area, i.e. 300mm SLR scenario. The distance to the 20-m isobath was determined by measuring the distance from the last beach to the nearest point of the 20-m isobath using bathymetric data provided by EM. Parameters would have different levels of coastal protection or response depending on the extent of impact (Palmer et al. 2011).
Conclusion
Dakota's official settlement, at Isipingo Beach (approximately 8 km north-east along the coast from Amanzimtoti, Figure 2), was chosen as the site because it falls within the high-risk zone; it is an informal settlement with a very vulnerable population of residents and its behavioral factors, namely the degradation of dunes by settlement residents, increases the risk of dune failure. The predicted extent of Mimusops caffra (M. caffra) trees at each site was determined by dividing the shoreline between transect lines into unit blocks and interpolating the number of trees within each block based on the number of trees occurring along 20-meter segments and including the 10 m wide strip of each transect line. The transects, which were linear and starting from the fore dunes up to 100 m inland, were separated by an equal distance of approximately 500 m, therefore a total of four transects were conducted along a coastal stretch of about 2 km at both sites .
Introduction
Identifying and mapping high SLR risk areas
CVI and CoastKZN maps
CVI maps were created using CoastKZNTM (https://maps.coastkzn.co.za/CoastKZN/) illustrating both coastal risk lines and sensitive areas, and parts of the EM coastline were mapped. Since the coastline is extensive, it is not possible to present the entire EM coastline with the necessary detail on one map. Therefore, the rest of the coastline is presented in a separate file (PDF format) in Annex A.
CVI Analysis
Properties within 100 m of HWM and located in neighboring areas with extremely high CVI scores may potentially be at risk (Palmer et al. 2011). The proximity of these properties to the HWM is important in determining the level of comparative risk, with developments, including infrastructure, that are within 2 m (vertical distance) of the HWM more likely to be affected by SLR impacts and associated extreme weather events than structures. further inland (Palmer et al. 2011). According to the CVI, Umhlanga, south of the Durban harbor entrance (ie, the whaling station), near the mouth of the Mlazi River and Newsel Beach have sewage pipes that are highly vulnerable.
Risk assessment of SLR impacts on coastal ecosystems (dunes and forests)
Classification of land use (NFEPA, D’MOSS, NPAs) assessment
The establishment of NPAs has been recognized as a way to guarantee the conservation of biodiversity and protection of ecosystem services (Rouget et al. 2016). This worsens the management of biodiversity and ecosystem services within an urban environment (Rouget et al. 2016). EM seeks an independent conservation strategy for ecosystem services related to safeguarding biodiversity (Rouget et al. 2016).
Analysis of developments potentially impacted by future SLR
An abbreviated version of the property valuations is presented below, and other valuations for the rest of the EM coast are presented in a separate pdf file as Appendix C. There was no promise that the local government would agree to the renovations, leaving landowners at risk of being instructed to get rid of interventions. The damaging outcome of the 2007 storm is a reflection of the city's unpreparedness to respond to the storm.
Risk assessment of coastal ecosystems
The width of the beach affects coastal vulnerability by acting as a barrier, reducing wave energy (Musekiwa et al. 2015). The wider the beach, the greater the ability of the beach to reduce wave energy as well as the impact of SLR and associated severe weather events. Towards the end of the transect (100m) there is no significant impact by wind on trees, except for transect three in Sibaya Forest where there is one M.
Conclusion
Introduction
Social understanding of the distribution and consequences of SLR impacts and adaptation measures in coastal communities around the world is still limited (Martinich et al. 2013). This is still one of the biggest issues of dialogue between the countries participating in the global discussions for the development of the climate pact. As a result, ad hoc practices by landowners to adapt to climate change will be constrained by increased government interventions, thereby reducing risk transfers to other properties and public space along the coast (O'Donoghue et al. 2021).
Recommendations
The CVI analysis shows that those regions with developments (i.e. private property) within the 100m HWM, both the local government and homeowners should consider cooperating in installing geofabric sandbags to prevent the effects of coastal erosion will increase as hazards may be moved elsewhere along the coast. the EM coast if individual action is not coordinated. In addition, the classified municipal infrastructure within the 100 m HWM, according to the CVI analysis, in terms of future planning on existing municipal infrastructure in light of SLR effects along the EM coastline, the EM modeled SLR projections for three scenarios ( 300, 600 and 1000 mm) should be considered during the decision making process to assist in moving infrastructure currently within the risk zone, according to the CVI, to low risk areas (i.e. beyond the 1000 mm fallback line) , if applicable. From the risk assessment of coastal ecosystems, future research into applying the Vegetation Index to particular parts of the EM coastline is needed to better understand how vulnerable coastal ecosystems are to SLR effects in Durban.
Future studies
Linear and non-linear sea level changes in Durban, South Africa South African Journal of Science. A perspective on sea level rise and coastal storm surge from South and East Africa: a case study near Durban, South Africa. Trends in coastal development and land cover change: the case of KwaZulu-Natal, South Africa.
