Geo-hydrological risk management for civil protection purposes in the urban area of Genoa (Liguria, NW Italy)

Abstract

Abstract. Over the past century the municipal area of Genoa has been affected by recurring flood events and several landslides that have caused severe damage to urbanized areas on both the coastal-fluvial plains and surrounding slopes, sometimes involving human casualties. The analysis of past events' annual distribution indicates that these phenomena have occurred with rising frequency in the last seventy years, following the main land use change due to the development of harbour, industrial, and residential areas, which has strongly impacted geomorphological processes. Consequently, in Genoa, civil protection activities are taking on an increasing importance for geo-hydrological risk mitigation. The current legislative framework assigns a key role in disaster prevention to municipalities, emergency plan development, as well as response action coordination in disaster situations. In view of the geomorphological and environmental complexity of the study area and referring to environmental laws, geo-hydrological risk mitigation strategies adopted by local administrators for civil protection purposes are presented as examples of current land/urban management related to geo-hydrological hazards. Adopted measures have proven to be effective on several levels (planning, management, structure, understanding, and publication) in different cases. Nevertheless, the last flooding event (4 November 2011) has shown that communication and public information concerning the perception of geo-hydrological hazard can be improved.

Geohydrological hazards and urban development in the Mediterranean area: an example from Genoa (Liguria, Italy)

“…A number of authors have studied geohydrological hazards and recent increase thereof by analysing meteorological and climate factors and their interaction with the complex orography of Genoa and surrounding localities (Pasquale et al, 1994;Russo and Sacchini, 1994;Russo et al, 2000;Cevasco et al, 2010;Sacchini et al, 2012;Brandolini et al, 2012;Faccini et al, 2014Faccini et al, , 2015a.…”

“…These convective systems have recently affected different locations Tropeano et al (1993Tropeano et al ( , 1995; Faccini et al (2014Faccini et al ( , 2015a over the Ligurian Gulf , causing flash floods arising from rainfall intensities of over 500 mm/6 h or 180 mm/1 h. The most recent of these events occurred on November 2014 in Genoa. These phenomena have been recurring and have been particularly violent in recent years, especially the last events that took place in Varazze and Sestri Ponente, Genoa, in 2010 (Faccini et al, 2015b), Cinqueterre (Cevasco et al, 2013;Buzzi et al, 2014) and Bisagno Valley, Genoa, in 2011 (Brandolini et al, 2012) and 2014 (Faccini et al, 2015a, c).…”

Relationship between man-made environment and slope stability: the case of 2014 rainfall events in the terraced landscape of the Liguria region (northwestern Italy)

“…Since the Middle Ages, the effect of human activities has been particularly evident in Liguria territory, which has been progressively and intensely modified landscape structure and appearance (Faccini et al 2009;Brandolini et al 2012). The landscape, almost completely occupied by hills and mountains with steep slopes, has been subjected to hundreds of years of human management, primarily represented by anthropic terraces, and later by road and urban area developments.…”

“…It should be noted that in Liguria region, the current population growth rate represents a huge push factor for the development of urbanized areas also in hazardous areas (Brandolini et al 2008;Cevasco et al 2008;Brandolini et al 2012;Faccini, Luino, et al 2015) in both flat and slope areas (Brandolini et al 2012;Faccini et al 2016). This demanded a communication lines improvement across the valleys flanks, to enhance the accessibility to urban facilities and causing a further change of the original profile of the slope.…”

A hydrological analysis of the 4 November 2011 event in Genoa

“…The growth of the city over the final reaches of the Bisagno creek and the Fereggiano brook during the second part of the century created hydraulic conditions prone to disastrous floods (Brandolini et al, 2012).…”