Risks for the Population along the Bulgarian Black Sea Coast from Flooding Caused by Extreme Rise of Sea Level

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Abstract:

The geographical status of coastal zone as a boundary between sea and land makes it especially attractive, both for settlement and the implementation of various human activities. This in turn leads to accelerated urbanization of coastal areas. Generally, coastal areas cover only a fraction of the surface of the Earth, but they concentrate around 60 % of the world’s population. Bulgarian Black Sea coast is also no exception to this trend. According to data from the last national census, Black Sea municipalities comprise 5.21 % of the country’s territory and 8.85 % of the population. At the same time, as a consequence of global climate change and the trend towards increasing sea levels, natural risks of extreme weather events are becoming more important and more dangerous. This study assesses the risks of ris­ing sea level for the population defined in different scenarios of increase in the level. It uses official data on the population in coastal towns and topographic maps to determine low-laying coastal areas. Analysis was conducted using a GIS ArcInfo 9.1. The most vulnerable coastal areas are identified and assessed on pre­liminary given scenarios of sea level rise from 1 to 5 meters. As a case study, the risk for the coastal population of the biggest Bulgarian Black Sea resort Sunny Beach is analysed in detail. Applying 3D GIS modeling, visualisation and accurate assessment of flooded coastal areas are performed, and numbers of population po­tentially endangered in case of different scenarios of sea level rise are estimated. The obtained results have significant practical importance and could serve as a pri­mary base in coastal decision-making, for the needs of civil protection authorities and other prevention/mitigation measures in hazard prone coastal zones.