Coastal Flood Vulnerability Research Articles

Flood impact in the Mekong Delta, Vietnam

The Vietnamese Mekong Delta (VMD) has an important role in terms of food security and socio-economic development of the region. The VMD is a densely populated area and is a social and economic hotspot for coastal hazard risks and vulnerability. The amount of people exposed to flooding, storm surges and seasonal river floods in VMD is estimated to increase as the sea level rises, land-use changes and urbanization in flood-prone areas is growing. Therefore, it is necessary to focus on assessing and mapping flood hazard, risk and vulnerability of the Mekong delta. There are many flood hazard and risk studies carried out in the VMD, however very little is done with respect to vulnerability. The region is facing a rapid economic growth and vulnerability to floods becomes an important issue to be addressed.The study presented here focuses on mapping of the vulnerability of the VMD, based on the situation in the area and on the available data. The study evaluates the VMD districts from vulnerability point of view and presents maps, which will be helpful to the decision makers who need to take measures on how to reduce and mitigate the flood impact in the area. Collaboration between deltas' administrations, multiple stakeholders and organizations, at national and international level (delta alliances), has to be undertaken to support the most vulnerable areas and to learn from each other. Mapping vulnerability offers the opportunity to get a broad overview on affected areas and on possible adaptation options that could be applied, directing resources at more in-depth investigation of the most promising adaptation strategies. Moreover, at a later stage, it can also serve to evaluate the effectiveness of the adaptation measures.The present study presents a map of flood vulnerability for the VMD for the years 2000 and 2050 (see Main Map). The map is created by applying Coastal Cities Flood Vulnerability Index (CCFVI) methodology; the flood map will overlay flood hazard in order to create flood risk maps using tools such as ArcGIS.

A flood vulnerability index for coastal cities and its use in assessing climate change impacts

Worldwide, there is a need to enhance our understanding of vulnerability and to develop methodologies and tools to assess vulnerability. One of the most important goals of assessing coastal flood vulnerability, in particular, is to create a readily understandable link between the theoretical concepts of flood vulnerability and the day-to-day decision-making process and to encapsulate this link in an easily accessible tool. This article focuses on developing a Coastal City Flood Vulnerability Index (CCFVI) based on exposure, susceptibility and resilience to coastal flooding. It is applied to nine cities around the world, each with different kinds of exposure. With the aid of this index, it is demonstrated which cities are most vulnerable to coastal flooding with regard to the system’s components, that is, hydro-geological, socio-economic and politico-administrative. The index gives a number from 0 to 1, indicating comparatively low or high coastal flood vulnerability, which shows which cities are most in need of further, more detailed investigation for decision-makers. Once its use to compare the vulnerability of a range of cities under current conditions has been demonstrated, it is used to study the impact of climate change on the vulnerability of these cities over a longer timescale. The results show that CCFVI provides a means of obtaining a broad overview of flood vulnerability and the effect of possible adaptation options. This, in turn, will allow for the direction of resources to more in-depth investigation of the most promising strategies.

Climate change impact on flood hazard, vulnerability and risk of the Long Xuyen Quadrangle in the Mekong Delta

The Vietnamese Mekong Delta (VMD) has an important role in terms of food security and socio-economic development of the region; however, it is one of many areas of the world vulnerable to floods resulting from sea level rise (SLR) due to climate change. Therefore, management of flooding is a priority at national and regional levels in Vietnam. The Long Xuyen Quadrangle is the most important region in the VMD in terms of agriculture and economy. In the present work, flood hazard, vulnerability and risk were assessed and mapped to identify the priority areas in the Long Xuyen Quadrangle for flood mitigation. A hydrodynamic model was used to simulate the flood event of 2000 when a flood of 20-year return period occurred and caused loss of human lives and extensive damage. The calibrated model was then used to simulate a possible flood event in 2050 due to SLR. The resulting flood depth of the simulation was used to prepare inundation maps and to analyse flood hazard in this region, as well. The flood vulnerability of the region was assessed using the coastal areas flood vulnerability index (FVI) method. The FVI was determined by district, and flood vulnerability maps were developed based on these data. The results indicate that the major part of the study area (35.4%) can be classified as being at high risk. It was also found that 32.7% of the area is under medium risk and only about 18.4% is under very low and low risk; 10.2% of the total area is not subjected to flood risk. We show that district level flood vulnerability maps are potentially useful for decision makers and the public in planning better measures for adaptation and mitigation of the negative impacts of flooding.