Soil sealing along the Beirut coast during half a century marked by population growth and refugee inflows

Land take by urbanization has increased significantly in the last decades, seriously contributing to the loss and degradation of the land capital. Urban sprawl and the related soil consumption are a major environmental and urban planning issue in the West Asian regions, particularly in the recent context marked by fast economic development and by regional conflicts that produced waves of war refugees and economic migrants. This study quantifies soil sealing due to the urban development between 1962 and 2020 in 28 municipalities located along the coastal strip and the coastal hill range of the Beirut and Mount Lebanon Governorates, in Lebanon, and discusses the impacts of urbanization processes on important ecosystem services such as food security and hydrological risks. The study is based on original data derived from historical topographic maps and from recent geospatial datasets. The two datasets have been generated and combined in a GIS environment by means of an original method that proved to be effective to perform detailed urban change analyses over long time spans covering periods in which no satellite information with sufficient resolution was available. An overall 54.0% increase in land surface taken by urbanization was observed in the study area between 1962 and 2020. This amount is not exceptional if compared to other fast-growing urban centers of the region. It is, however, very high considering the high overall degree of saturation (83.5%) of the available land space, the very dense continuous urban fabric, and the high level of soil sealing on the hill slopes overlooking the plain. These aspects raise concerns about the environmental sustainability of the urbanization process. A very sensitive situation is represented by the suburban areas located on the hill sides and still destined to agricultural crops, which preserve high value traditional rural landscapes. Urgent measures should be taken, framed within improved urban planning policies, to prevent further losses and to mitigate the impacts of the present-day soil sealing situation.