GIS-based risk assessment for the Nile Delta coastal zone under different sea level rise scenarios case study: Kafr EL Sheikh Governorate, Egypt

摘要

Sea level changes are caused by several natural phenomena, including mainly ocean thermal expansion, glacial melt from Greenland and Antarctica. It was estimated, in this respect, that global average sea level rose, during the 20th Century, by at least 10 cm. This trend is expected to continue and most likely accelerated during the 21st Century due to human-induced global warming. Global average sea level is expected to rise, by the year 2100, due to global warming between 0.18 and 0.59 cm. Such a rise in sea-level will significantly impact coastal areas due to the high concentration of natural and socioeconomic activities and assets located along the coast. The northern coastal zone of the Nile Delta is generally low land, and is consequently vulnerable to direct and indirect impacts of sea level rise (SLR) due to climate changes, particularly inundation. Despite the uncertainty associated with developed scenarios for climate change and expected SLR, there is a need, according to precautionary approach, to assess and analyze the impacts of SLR. Such an assessment, on one hand, can assist in formulating effective adaptation options to specific, sometimes localized, impacts of SLR. On the other hand, such an analysis can contribute significantly to the development of integrated approach to deal with the impacts of SLR. The objective of this paper is to assess and spatially analyze the risks of expected sea level rise (SLR), in particular inundation, and its implications up to the year 2100 in Kafr El Sheikh Governorate, Egypt, using GIS techniques. For that purpose, a GIS was developed for the study area and then utilized to identify the spatial extent of those areas that would be vulnerable to inundation by SLR. Moreover, various land uses/land covers susceptible to such inundation were identified. Results indicate that more than 22.59 % and 24.50 % of the total area of Kafr El Sheikh Governorate would be vulnerable to inundation under B1 and A1FI (IPCC most optimistic and pessimistic scenarios), respectively. No significant difference was noticed between the two scenarios in terms of spatial extent of SLR impacts. It was also found that a significant proportion of these areas were found to be currently either undeveloped or wetlands. Moreover, it was found that about 90.13 % of the vulnerable areas are actually less exposed to the risks of SLR due to the existence of a number of man-made features, not intended as protection measures, e.g. International Coastal Highway, that can be used to limit the areas vulnerable to inundations by SLR.