'Blue-green' corridors as a tool for mitigation of natural hazards and restoration of urbanized areas: A case study of Belgrade city

Abstract

Urbanized areas constantly need new surfaces for building of commercial, residental or infrastructure facilities. Belgrade, the capital of Serbia and a big regional center, with 2,000,000 inhabitants, covers a territory of 3,500 km2. Decreasing of surfaces under forest vegetation, urbanization and inadequate agricultural measures have caused intensive erosion and more frequent torrential floods. Belgrade authorities have defined a new strategy for land use and urban planning in order to decrease the risk from destructive erosion processes and torrential floods and help the establishment of new recreational areas, preservation of biodiversity and mitigation of the 'heat island' effect. The strategy is based on the restoration of 'blue-green' corridors (residuals of open streams and fragments of forest vegetation). The restoration of 'blue-green' corridors is presented at the experimental watersheds of the Kaljavi and Jelezovac streams. The restoration works will be performed in the 2014-2020 period, on the basis of erosion and stream control demands, as well as environmental and social requests, including biological, soil-bioengineering activities and certain administrative measures. The forest surfaces will be increased by 1.38 km2 (18.11% of the total area). The restoration of 'blue-green' corridors in the experimental watersheds will decrease the values of maximal discharges (p = 1%) by about 50%, and the volumes of direct runoff by about 40%. Erosive material production and transport will be decreased by about 44% in the Kaljavi stream watershed, and 37% in the Jelezovac stream watershed. Ten kilometers of sealed walking and cycling paths, 1.7 km of unsealed forest paths, six open gyms and seven rest areas will strengthen the potential of this area for sports and recreation. The restoration will help the protection and controlled usage of the natural and cultural values in the area, and the connection of 'blue-green' corridors at different spatial levels. The final goal is the creation of a network of 'blue-green' corridors in the territory of Belgrade city, which provides both effective erosion and stream control and environmental and social services.