Integrated Assessment of Coastal Exposure and Social Vulnerability to Coastal Hazards in East Africa

Abstract

An index of vulnerability to coastal change, integrating indices of social vulnerability and exposure to coastal hazards, was created for East Africa to identify ‘areas of priority concern’ for risk reduction. Currently, 22% of East Africa’s coastline and 3.5 million people are at higher levels of exposure to coastal hazards, which would increase, respectively, to 39% and 6.9 million people if mangroves, coral reefs and seagrasses are lost. Madagascar and Mozambique show the largest proportion of the coastline at higher exposure, while Kenya and Tanzania benefit the most from natural coastal protection. Coral reefs protect 2.5 million people from higher exposure, mostly in Mombasa, Zanzibar and Dar es Salaam. Considering Mozambique, Kenya and Tanzania, the latter is the least, and the former is the most vulnerable. Under current conditions, 17 (out of 86) coastal districts are considered ‘areas of priority concern’; four of these are critically exposed as over 90% of their shoreline length are at higher exposure (Zavala, Inharrime, Manhiça and Mandlakaze, all in southern Mozambique). These locations are of critical concern for any present or future coastal development due to the high level of exposure posed to both vulnerable people and investments. Habitat loss would increase the number of ‘priority concern’ districts to 24; some would show great increase in the population exposed (e.g. Pemba and Mossuril in Mozambique). Applying this knowledge to identify where ecosystem-based management should be prioritised to promote social and environmental resilience is timely and urgent in East Africa.

African heritage sites threatened as sea-level rise accelerates

“…The eastern African coast, considered a region of high diversity of seagrass 41 , is subject to frequent anthropogenic disturbance, resulting in the loss of about 21% of Kenya's seagrass cover between 1986 and 2016 42 . Such transitions could have further indirect effects and weaken natural coastal protection, further exacerbating flood risk; with substantial social consequences 43 . The number of sites and area exposed, as well as total number of sites and the percentage of which is exposed, are shown.…”

Beyond the single index: Investigating ecological mechanisms underpinning ecosystem multifunctionality with network analysis

“…For example, the effect of denitrifying bacteria on denitrification rates that convert reactive nitrogen into N 2 gas, effectively removing N from the system (Vieillard et al., 2020 ). Macrofaunal organisms through their biological activity such as structure building and sediment particle movement introduce organic carbon and oxygen to deeper layers of sediment where denitrifiers reside (Siwicka & Thrush, 2020 ), and therefore, their role, although indirect, is critical in mediating denitrification rates (Vieillard & Thrush, 2021 ). Low explanatory power of variables should not discourage us from studying the range of drivers that regulate multifunctionality.…”

Assessing Coastal Vulnerability and Evaluating the Effectiveness of Natural Habitats in Enhancing Coastal Resilience: A Case Study in Shanghai, China

“…The CVI considers physical and social factors to measure vulnerability, whereas the EI incorporates climate change scenarios, making it useful for coastal habitat assessments. The Coastal InVEST model assesses coastal vulnerability using both indicators and considers future changes under several climate change scenarios [54][55][56][57][58][59]. In the study by Zhang et al [27], which assessed the coastal vulnerability of Bohai in China, the researchers considered a total of 15 variables (5 variables for each subindex), including geomorphology, natural habitats, population density, urbanized area, per capita GDP, and medical services, and computed the final CVI for each coastline segment based on the formula CVI = (EI + SI)/ACI [27].…”

“…To date, this model has been applied in many cases around the world, such as the United States, Italy, China, and East Africa, contributing to coastal protection and management from local to cross-national scales [56][57][58][59]. This research used a methodology that has been proven effective in previous cases to evaluate the vulnerability of Shanghai's coastal areas.…”