Lead Authors: Marco Bindi (Italy), Sally Brown (UK), Ines Camilloni (Argentina), Arona Diedhiou (Ivory Coast/Senegal), Riyanti Djalante (Japan/Indonesia), Kristie L. Ebi (USA), Francois Engelbrecht (South Africa), Joel Guiot (France), Yasuaki Hijioka (Japan), Shagun Mehrotra (USA/India), Antony Payne (UK), Sonia I. Seneviratne (Switzerland), Adelle Thomas (Bahamas), Rachel Warren (UK), Guangsheng Zhou (China)

Impacts of 1.5°C Global Warming on Natural and Human Systems

Coral reefs can provide significant coastal protection benefits to people and property. Here we show that the annual expected damages from flooding would double, and costs from frequent storms would triple without reefs. For 100-year storm events, flood damages would increase by 91% to $US 272 billion without reefs. The countries with the most to gain from reef management are Indonesia, Philippines, Malaysia, Mexico, and Cuba; annual expected flood savings exceed $400 M for each of these nations. Sea-level rise will increase flood risk, but substantial impacts could happen from reef loss alone without better near-term management. We provide a global, process-based valuation of an ecosystem service across an entire marine biome at (sub)national levels. These spatially explicit benefits inform critical risk and environmental management decisions, and the expected benefits can be directly considered by governments (e.g., national accounts, recovery plans) and businesses (e.g., insurance). Coral reefs provide significant coastal protection from storms but they have experienced significant losses. Here the authors show that the annual damages from flooding would double globally without reefs and they quantify where reefs provide the most protection to people and property.

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The global flood protection savings provided by coral reefs

There is growing awareness that ‘nature-based solutions' (NbS) can help to protect us from climate change impacts while slowing further warming, supporting biodiversity and securing ecosystem servi...

https://royalsocietypublishing.org/doi/pdf/10.1098/rstb.2019.0120

Understanding the value and limits of nature-based solutions to climate change and other global challenges

Do Not Cite, Quote or Distribute 4-1 Total pages: 139 1 Chapter 4: Sea Level Rise and Implications for Low Lying Islands, Coasts and Communities 2 3 Coordinating Lead Authors: Michael Oppenheimer (USA), Bruce Glavovic (New Zealand), Tuhin Ghosh 4 (India) 5 6 Lead Authors: Amro Abd-Elgawad (Egypt), Rongshuo Cai (China), Miguel Cifuentes-Jara (Costa Rica), 7 Rob Deconto (USA), John Hay (Cook Islands), Jochen Hinkel (Germany), Federico Isla (Argentina), 8 Alexandre K. Magnan (France), Ben Marzeion (Germany), Benoit Meyssignac (France), Zita Sebesvari 9 (Hungary), AJ Smit (South Africa), Roderik van de Wal (Netherlands) 10 11 Contributing Authors: Maya Buchanan (USA), Gonéri Le Cozannet (France), Catia Domingues 12 (Australia), Virginie Duvat (France), Tamsin Edwards (UK), Miguel D. Fortes (Philippines), Thomas 13 Frederikse (Netherlands), Jean-Pierre Gattuso (France), Robert Kopp (USA), Erwin Lambert (Netherlands), 14 Elizabeth McLeod (USA), Mark Merrifield (USA), Siddharth Narayan (US), Robert J. Nicholls (UK), 15 Fabrice Renaud (UK), Jonathan Simm (UK), Jon Woodruff (USA), Poh Poh Wong (Singapore), Siyuan Xian 16 (USA) 17 18 Review Editors: Ayako Abe-Ouchi (Japan), Kapil Gupta (India), Joy Pereira (Malaysia) 19 20 Chapter Scientist Maya Buchanan (USA) 21 22 Date of Draft: 20 April 2018 23 24 Notes: TSU Compiled Version 25 26

/pdf/sea-level-rise-and-implications-for-low-lying-islands-coasts-1ptd3trc7d.pdf

Sea Level Rise and Implications for Low Lying Islands, Coasts and Communities

Urban natural environments as nature-based solutions for improved public health – A systematic review of reviews

Coastal flood management has become a topic of great relevance in the recent past due to a combination of accelerated sea-level rise and storminess associated with climate change and a continuing increase in the value of natural and anthropogenic coastal assets. The conflict of interest between the value of our coastal assets and the costs of protecting them is, at present, largely resolved with the help of risk-based analyses. In the past decade or so, systems-based approaches to risk assessments have been developed that attempt to understand relationships within the coastal system at a broad scale rather than at the level of individual components (Sayers, Hall & Meadowcroft, 2002; Townend, 2003). One common framework for this type of analysis is the Driver-Pressure-State-Impact-Response (DPSIR) model (e.g. Wheater et al., 2007; EEA Integrated Assessment Portal, 2007). For coastal flooding however, the Source – Pathway – Receptor – Consequence (SPRC) model is believed to provide a better instantaneous representation of the physical flooding process with regard to the propagation and consequences of a particular flood event and has been used in several recent coastal flood risk assessment studies (Bakewell & Luff, 2008; Thorne et al., 2007; FLOODsite Consortium, 2009). The main strengths of this model lie in its simplicity, inherent flexibility and ability to capture system linkages during a flood event. Though widely cited, there is however hardly any literature that describes the manner in which this conceptual model is used to shape flood propagation and risk evaluation studies. It is felt that the SPRC model in its current form is weak and not being implemented to its full potential. The ongoing EU project ‘THESEUS: Innovative Coastal Technologies for Safer European Coasts in a Changing Climate’ aims to address both the human and ecological consequences of a flood event and proposes use of the SPRC model as the basis for integrating these aspects in terms of coastal flood management while providing a systems overview of the flood propagation process (Hanson, 2010). In order to achieve this, it is essential that the SPRC framework be modified and strengthened as a conceptual model in order to enable representation of the various coastal systems within the scope of the study. This paper describes the SPRC model delineating its strengths and weaknesses in its current form. The relationship of SPRC to other systems-based risk models such as the DPSIR model is discussed and suggestions are made with regard to building on SPRC with inputs from the DPSIR model in order to obtain a more comprehensive systems model. A systems diagram based on the SPRC concept is proposed as an initial step in representing the state of the coastal flood system. The systems diagram is built starting with the sources, through the various physical elements of interest to the outermost entities of the defined system. The main advantage of the proposed diagram is that any element, natural or artificial, may be picked out as a receptor, thereby automatically designating the role of ‘pathway’ to all elements linking it to the sources of the event. Such a system diagram affords a very good overview of the various elements and linkages that have been recognised in the study and as such, constitutes an effective and intuitive conceptual model. Once built, such a model may be used to characterise any flood event that falls within the defined boundaries of the study at any resolution. Using the SPRC framework as described above system diagrams are built for two sites being studied in the EU THESEUS project. Based on these, suggestions are made to help improve the conceptual model and provide a strengthened basis for comprehensive integrated coastal flood risk assessments for different coastal systems.

https://meetingorganizer.copernicus.org/EGU2011/EGU2011-10394.pdf

Use of the source - pathway - receptor - consequence model in coastal flood risk assessment

Mangroves and other coastal ecosystems act as natural defenses that protect people and property from storms, floods, erosion, and other coastal hazards, reducing coastal risk. Mangroves protect coastlines by decreasing the risk of flooding and erosion. The roots of mangroves retain sediments and prevent erosion, while the prop roots, trunks and canopy reduce the force of incoming wind and waves and reduce flooding. The Philippines has lost hundreds of thousands of hectares of mangroves in the last century. When mangroves are degraded or destroyed, the coast line becomes more exposed to the destructive impacts of waves and storm surge, and coastal communities have greater risks from the impacts of storms, floods, and sea level rise. The Philippines is at high risk from coastal hazards and natural defenses can help reduce these risks. This Technical Report, and its accompanying Policy Brief, provide a social and economic valuation of the flood protection benefits from mangroves in the Philippines. This work aims to support decisions across development, aid, risk reduction and conservation sectors as they seek to identify sustainable and cost-effective approaches for risk reduction. This Technical Report applies the Expected Damage Function approach recommended by the World Bank to quantify the risk reduction benefits from mangroves in the Philippines. Using high-resolution flooding models, the Report examines the flooding that would occur with and without mangroves under different storm conditions throughout the Philippines, and estimates the annual expected benefits of mangroves for protecting people and property in social and economic terms.

Valuing protective services of mangroves in the Philippines : technical report

There is a growing need for coastal and marine restoration, but it is not clear how to pay for it given that environmental funding is low, and national budgets are stretched in response to natural hazards. We use risk-industry methods and find that coral reef and mangrove restoration could yield strong Return on Investment (ROI) for flood risk reduction on shorelines across more than 20 Caribbean countries. These results are robust to changes in discount rates and the timing of restoration benefits. Data on restoration costs are sparse, but the Present Value (PV) of restored natural infrastructure shows that ROI would be positive in many locations even if restoration costs are in the hundreds of thousand per hectare for mangroves and millions per km for reefs. Based on these benefits, we identify significant sources of funding for restoring these natural defenses. 

Return on investment for mangrove and reef flood protection

Coastal flood assessments often require the analysis of a complex system of flood sources, pathways and receptors. This can be challenging for traditional numerical modelling approaches. In this paper we use a Bayesian networks approach to assess coastal floodplains as networks of inter-linked elements. A Bayesian network (Bn) model is built to describe flood pathways and estimate flood extents for different extreme events. The network of the Bn model is constructed from a quasi-2D Source – Pathway – Receptor (SPR) systems diagram. The Bn model is applied in Teignmouth in the UK, a coastal floodplain of typical complexity. It identifies two key flood pathways and assesses their sensitivity to changes in sea levels, beach widths and coastal defences. The advantages, utility and limitations of the Teignmouth Bn model are discussed. The process of 2D SPR and Bn model construction helps identify gaps in floodplain understanding and description. The Bn model quantifies inundation probabilities and facilitates the rapid identification of critical pathways and elements, before committing resources to further detailed analysis. The approach is transferable and can be readily applied in local-scale coastal floodplains to obtain a systems-level understanding and inform numerical modelling assumptions.

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A Bayesian network model for assessments of coastal inundation pathways and probabilities

Coastal habitats are highly threatened ecosystems that are sensitive to complex sets of natural and human drivers. Europe’s coastal habitats are protected from damage due to human activity by the EU Habitats Directive, and are required to be mapped within flood risk assessments by the EU Floods Directive. Ecological vulnerability and risk assessments are a common way of assessing the impacts on these habitats due to human and natural drivers. Coastal flood risk assessments therefore often include assessments of the vulnerability of coastal habitats. Flood risk assessments also evaluate, where relevant, the mitigation services provided by coastal habitats. The two aspects of coastal habitats – their flood mitigation service and their ecological vulnerability are strongly correlated; however these are usually treated separately within flood risk assessments. One of the goals of the EU THESEUS project is the integrated consideration of coastal habitats within flood risk assessments. This paper investigates the integration within flood risk assessments of the two aspects of coastal habitats using the 2D SPR conceptual model. The construction of the model is first illustrated by application to a generic study site. The model is then applied to a case-study where data on habitat elevations and vulnerabilities to flood events have been collected. The model provides a unique and robust means of combining information on ecological vulnerability indices for different habitat associations with information on their distribution and spatial relationships within the coastal floodplain. Used in conjunction with information on habitat vulnerability indices, the conceptual model serves as a powerful tool for integrated and structured consideration of coastal habitats within flood risk assessments

https://icce-ojs-tamu.tdl.org/icce/index.php/icce/article/download/6865/pdf

Siddharth Narayan

Papers

Use of the source - pathway - receptor - consequence model in coastal flood risk assessment

Valuing protective services of mangroves in the Philippines : technical report

Return on investment for mangrove and reef flood protection

A Bayesian network model for assessments of coastal inundation pathways and probabilities

Coastal habitats within flood risk assessments: role of the 2d spr approach