Coastal Floods Induced by Mean Sea Level Rise—Ecological and Socioeconomic Impacts on a Mesotidal Lagoon

Coastal floods are currently a strong threat to socioeconomic activities established on the margins of lagoons and estuaries, as well as to their ecological equilibrium, a situation that is expected to become even more worrying in the future in a climate change context. The Ria de Aveiro lagoon, located on the northwest coast of Portugal, is not an exception to these threats, especially considering the low topography of its margins which has led to several flood events in the past. The growing concerns with these regions stem from the mean sea level (MSL) rise induced by climate changes as well as the amplification of the impacts of storm surge events, which are predicted to increase in the future due to higher mean sea levels. Therefore, this study aims to evaluate the influence of MSL rise on the inundation of Ria de Aveiro habitats and to assess the changes in inundation patterns resulting from frequent storm surges (2-year return period) from the present to the future, assessing their ecological and socioeconomic impacts. For this, a numerical model (Delft3D), previously calibrated and validated, was used to simulate the lagoon hydrodynamics under different scenarios combining MSL rise and frequent storm surge events. The numerical results demonstrated that MSL rise can change the vertical zonation and threaten the local habitats. Many areas of the lagoon may change from supratidal/intertidal to intertidal/subtidal, with relevant consequences for local species. The increase in MSL expected for the end of the century could make the lagoon more vulnerable to the effect of frequent storm surges, harming mostly agricultural areas, causing great losses for this sector and for many communities who depend on it. These extreme events can also affect artificialized areas and, in some cases, endanger lives.

Impact of Coastal Flood on Building, Infrastructure, and Community Adaptation in Bukit Bestari Tanjungpinang

Coastal flood in Indonesia, namely as banjir rob, is a phenomenon that increases seawater to inundate around the tidal area. In Tanjungpinang, cases of coastal floods become a serious problem for people living in this area. This research aims to model the coastal flood inundation by modeling water inundation with a maximum level increase scenario. Its model was used to estimate coastal floods' impact on houses, buildings, and infrastructures with scenario 2 meters of sea-level rise. On the other hand, the budget loss for restoration was estimated to study the effort of community adaptations with the ECLAC RAB method and observation to understand community adaptation. It was found that the spatial model succeeded in zoning inundation areas, which had a significant impact on houses, buildings, worship places, schools, and industrial at many 4112 units. From this case, the budget loss for the restoration of the physical environment was estimated at around 61994014.75 USD. In addition, the survey revealed the existing condition before and after the coastal flood. Several community efforts for adaptation were developing houses on stilt and hoarding the lowest land on-site location for build houses.

Multi-hazard mitigation challenges during the Covid-19 crisis? Evidence from the tropical regions

<p>Across the world, health and disaster managers face the challenge of responding to natural hazards such as cyclones, floods, and droughts while minimizing the impacts of Covid-19. The tropical cyclones and floods affect vulnerable communities and result in losses of life and damages. The drought situations can weaken the agricultural economy and local livelihoods. How these impacts could be amplified by the Covid-19, mainly during the monsoon season, is of great importance for informed-planning. The present study aims to assess exposure to hydro-meteorological hazards (tropical cyclones, floods, and droughts) in terms of the number of people affected, economic activities exposed, and how these hazards superimposed over the Covid-19 pandemic could impact the different phases of disaster risk management cycle. The study focuses on three deltas, namely, Ganges-Brahmaputra-Meghna (GBM) delta spanning over India and Bangladesh, and Red River (RR) and Mekong River (MK) deltas in Vietnam.</p><p>Present research found that the GBM delta suffers from frequent cyclones and floods and less with coastal floods and droughts, whereas the MK delta suffers from riverine and coastal floods and droughts. The RR delta faces frequent tropical cyclones, riverine and coastal floods, and droughts. Populations living in Red delta (100%) exposed more to tropical cyclone as compared to GBM (2.22%) and the Mekong delta (0%) with 50-year return period (RP). Similarly, about 36.46 (0.28), 83.24 (47.23), and 72.76 (33.49) % population of the GBM, RR, and MK deltas are exposed to riverine (coastal) flood hazards with 10-year RP, respectively. During May-Aug 2020, a maximum of 0.76, 100, and 33.49 % population in a month was exposed to meteorological drought (SPI3 below -1) in the GBM, RR, and MK deltas, respectively.</p><p>The results include probabilistic exposure of urban area, cropland, livestock, and GDP to major hydro-meteorological hazards on a similar line. In the second part, the study explores the number of Covid-19 cases reported at the administrative level 2 and draws qualitative inferences on how tackling multi-hazards in the deltas could have become more challenging during the ongoing pandemic and vice versa.  The study recommends that the pandemic has resulted in an urgent need to incorporate health emergency disasters while designing hydro-meteorological disaster management plans.</p>

The socio-ecologic aspects of nature-based solutions for coastal flooding mitigation

<p>Coastal flooding has been historically mitigated through engineered artificial (grey) infrastructures such as breakwaters, dikes, and sea walls. However, these structures have a pervasive long-term impact on coastal ecosystems (e.g. sediment transport disruption), and require constant maintenance, and have little resilience to climate change (e.g. hurricanes, sea-level rise) related events.  Grey infrastructures failed to mitigate the effects of coastal floods, and the damages were significantly less in areas where healthy coastal ecosystems were present. This highlighted the role and contribution of coastal habitats to mitigate coastal floods and adapt to new conditions. The inefficiency of grey infrastructure to mitigate the impact of extreme events and following ecosystem-based management led to the development of the Nature-Based Solutions (NBS) concept. In the context of coastal flooding mitigation, to reduce the effects of storm surges, wave action, and erosion, NSB can be designed using (1) natural solutions (e.g., the creation of marine protected areas), (2) soft engineering and ecological restoration practices (e.g., mangrove plantation), and (3) hybrid solutions, which integrates natural and grey infrastructures (e.g. artificial reefs). NBS integrate multiple international environmental agendas, for their capacity to provide multiple co-benefits (e.g. recreation, fisheries). NBS are also key for supporting other agendas and global objectives: the Sustainable Development Goals (e.g. SDG14), Green/Blue economy, coastal resilient and climate-adapted coastal communities, biodiversity targets of the Convention for Biological Diversity and Circular Economy.</p><p> </p><p><br>“Lithuanian National Ecosystem Services Assessment and Mapping (LINESAM)” No. 09.3.3-LMT-K-712-01-0104 is funded by the European Social Fund according to the activity “Improvement of researchers’ qualification by implementing world-class R&D projects” of Measure No. 09.3.3-LMT-K-712.</p>

Coastal Flood Responses in Manila Bay, the Philippines

In 2011, Sitio Pariahan in the northern part of Metro Manila, the Philippines’ capital region, was submerged after Typhoon Nesat hit the country. In fact, Sitio Pariahan is not the only one. Many parts of Manila Bay have slowly been sinking, causing the populations to be prone to coastal floods. According to the existing studies, coastal floods in Manila Bay areas are caused by climate-induced sea-level rise and land subsidence due to the excessive groundwater extraction and rapid urban development. However, it appears that the policies implemented by the government tend to be infrastructural, for example, dike construction, which could provide immediate protection but do not really solve the problem. This case study, therefore, presents a detailed account of coastal flooding in Manila Bay, particularly on its causes and policy options to address it. More specifically, it introduces the application of social contract to understand how the terms and conditions governing the state-citizens relations in the Philippines affect government’s rationale in choosing policy options to solve the coastal flood problem.