Mitigating flooding in a typical urban area in North Western Attica in Greece

D. Serbis, C. Papathanasiou, and N. Mamassis, Mitigating flooding in a typical urban area in North Western Attica in Greece, Conference on Changing Cities: Spatial Design, Landscape and Socio-economic Dimensions, Porto Heli, Peloponnese, Greece, June 2015.



Frequent floods in urban areas can pose threats to human lives and cause extensive devastation with long lasting consequences on properties and the environment. The frequency and impact of urban flooding are intensified by extended urbanization and the consequent land use change. More specifically, the expansion of impermeable areas in urban zones can cause rainfall events of low return period to produce the same or even more intense socioeconomic and environmental impact compared to rainfall events of high return period. For this reason, interventions in urban zones that are expected to deteriorate rainwater drainage conditions need to be accompanied by appropriate measures both structural and non-structural that ensure flood mitigation on the entire hydrological basin. In the absence of such measures which is usually the case, additional approaches to minimize flood impact need to be adopted. Flood effects are also intensified by poor urban design and inequitable development practices leading to greater water volumes that have to be managed in shorter times. A typical urban area that suffers from frequent flooding is the Community of Magoula, a community of 5000 habitats, located 21 km North West of Athens (Greece). The construction of a modern highway (Attiki Odos) that crosses the Community provided adequate flood protection locally, but was not accompanied by appropriate structural and non-structural measures to protect the entire basin. This paper presents an approach to expand insufficient infrastructure in order to provide adequate flood protection to the entire urban area of the Community of Magoula. In particular, the existing drainage pipe network of the area is expanded over a critical net of urbanised zones with low permeability, in order to mitigate flood events. The design of the proposed works was evaluated against both their capacity to successfully drain the flooded areas and the adequacy of the existing infrastructure to accommodate the incoming flow. The paper concludes with a set of complementary BMPs and non-structural measures that aim to ameliorate and mitigate flash flooding effects.

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