Hindcast high-resolution simulation of the most catastrophic rainfall event in Genoa City (7-8 October 1970): hydro-meteorological and geomorphological analysis

Liguria region is historically affected by severe hydro-meteorological events often resulting in dramatic death tolls and large socio-economic impacts. On 7-8 October 1970, Genoa, region capital city, was struck by the most catastrophic flood event of its history. On the evening of 7 October pre-frontal storms affected the western side of the city (Voltri, Prà and Pegli municipalities), while on 8 October 1970 an anticyclone block generated recurring convective systems that hit Genoa city and above all the Bisagno Valley. The heavy rainfall continued more than 24 h with highs at Bolzaneto rain gauge (Polcevera Valley, northwest of Genoa city center) where over 950 mm of rainfall in 24 hours was measured. Over the city center and the Bisagno Valley, 400 mm in 24 h was recorded. The Bisagno stream channels overflowed, submerging the city center. The 1970 event in Genoa City was also the most dramatic in terms of damage: 44 fatalities occurred and over 2000 individuals were evacuated. This study hindcasts the meteorological evolution of this event at high spatial resolution (1.5 km) and temporal one (1 hour) using the Weather and Research Forecasting (WRF) model by downscaling the ERA5 climatology developed by European Center for Medium-Range Weather Forecast (ECMWF). The weather hindcast scenario is compared with available meteorological observations as well as with recorded geomorphological impacts on Genoa city center and municipalities

High-Resolution Lightning Detection and Possible Relationship with Rainfall Events over the Central Mediterranean Area

Lightning activity is usually associated with precipitations events and represents a possible indicator of climate change, even contributing to its increase with the production of NOx gases. The study of lightning activity on long temporal periods is crucial for fields related to atmospheric phenomena from intense rain-related hazard processes to long-term climate changes. This study focuses on 19 years of lightning-activity data, recorded from Italian Lightning Detection Network SIRF, part of the European network EUCLID (European Cooperation for Lightning Detection). Preliminary analysis was dedicated to the spatial and temporal assessment of lightning through detection in the Central Mediterranean area, focusing on yearly and monthly data. Temporal and spatial features have been analyzed, measuring clustering through the application of global Moran\u2019s I statistics and spatial local autocorrelation; a Mann\u2013Kendall trend test was performed on monthly series aggregating the original data on a 5 7 5 km cell. A local statistically significant trend emerged from the analysis, suggesting possible linkage between surface warming and lightning activity

Bridging Terrestrial and Marine Geoheritage: Assessing Geosites in Porto\ufb01no Natural Park (Italy)

Interest in geoheritage research has grown over the past 25years and several countries have issued laws to encourage improvement and conservation. Investigations on geosites are prevalently carried out on land environments, although the study of underwater marine environments is also of paramount scienti\ufb01c importance. Nevertheless, due to the constraints of underwater environments, these sites have been little explored, also on account of the higher costs and di\ufb03culties of surveying. This research has identi\ufb01ed and assessed the terrestrial and marine geosites of the Porto\ufb01no Natural Park and Protected Marine Area, which are internationally famous owing to both the land scenic features and the quality of the marine ecosystem. The goal was to pinpoint the most suitable sites for tourist improvement and fruition and identify possible connections between the two environments. Inall,28 terrestrial sites and 27 marine sites have been identi\ufb01ed and their scienti\ufb01c value as well as their ecological, cultural, and aesthetic importance has been assessed. In addition, accessibility, services, and economic potential of geosites has also been taken into account. Both the updated database of terrestrial and marine geo sites in the Porto\ufb01no protected areas and the assessment procedure adopted can become useful tools for the managers of these sites and provide decision-makers with possible strategies for tourist development

Urban geomorphology of Genoa old city (Italy)

Field survey and geomorphological mapping in urban areas are difficult tasks, particularly those related to the recognition of natural landforms within cities. In this case, it is necessary to apply an integrated scientific approach by combining geomorphology with historical-geography. This paper presents the result of a multi-year survey carried out in the natural morphological amphitheatre where the historic centre of Genoa developed. Our research methods included field surveys in urban areas, interpretation of natural and anthropic landforms from maps and photographs, and analyses of the available borehole logs. As a result, we updated knowledge on urban geomorphology of Genoa old city. An original geomorphological legend has been adopted, including new entries for anthropogenic landforms, targeted at a better visual representation on the changes in the geomorphological landscape during more than one thousand years of urban development of the city. The geomorphological map of Genoa old city is presented as a useful tool for urban planning, as well as for an integrated cultural and landscape enhancement of the territory

Exposure\ua0to\ua0Geo\u2010Hydrological\ua0Hazards\ua0of\ua0the\ua0 Metropolitan\ua0Area\ua0of\ua0Genoa,\ua0Italy:\ua0A\ua0Multi\u2010Temporal\ua0 Analysis\ua0of\ua0the\ua0Bisagno\ua0Stream\ua0

Geo\u2010hydrological  risk  reduction  policies  are  becoming  a  critical  challenge  for  environmental sustainability, both at the national and international levels. The reason is twofold:  On the one hand, climate change has increase rainfall frequency and intensity, while on the other,  reckless urban expansion has increased exposure to such hazards over time. Italy is a country that  is very vulnerable to flood and landslide hazard; the city of Genoa, which, in recent decades, has  been frequently hit by severe floods, has risen to symbolize Italian geo\u2010hydrological risk. Recent  studies  on  Genoa\u2019s  geo\u2010hydrological  hazard  have  focused  on  the  analysis  of  hydrogeomorphological features of the Bisagno stream basin, yet their main focus was on hazard control.  Very little research has been done to enhance the understanding of the source of risk in such  catchments. This paper presents a study on the increased urban exposure and vulnerability to geohydrological hazard along the Bisagno stream catchment area over the last 200 years. Morphometric  analyses were coupled with historical documents showing the evolution of the urban layout in this  area. The results show that the \u201cBisagno Master Plan\u201d, a territorial planning strategy aimed at  reducing geo\u2010hydrological hazard and risk, has not produced the expected benefits. In spite of the  plan,  critical  changes  in  land  use  and  the  hydrographic  network,  along  with  uncontrolled  anthropization of the Genoa metropolitan area, has continued over the last two decade

Geoheritage map of the Portofino Natural Park (Italy)

This paper introduces a novel geoheritage map of the Portofino Natural Park. The park is an internationally well-known area, protected since 1935, located in the Ligurian Apennines, 25 km E of Genoa. It has 80 km of hiking trails which are used by visitors all year around. The map was produced by combining geological and geomorphological data, geoheritage elements and data from hiking and tourist maps. It is intended to be a base map from which can be derived applied maps. With appropriate integrations and simplifications, these can be useful tools for the management of highly frequented protected areas. The methodological approach involved aerial photo interpretation, bibliographical research, field work and the use of data from the Park archives. The original base map was produced by using a Digital Terrain Model raster (5 m) and vector layers for the different cartographical elements

Geological landscape and stone heritage of the genoa walls Urban park and surrounding area (Italy)

In the last 20 years the conservation and enhancement of cultural and landscape heritage sites have been increasingly promoted by specific national and international laws. Thematic maps from scientific studies facilitate the public promotion and understanding of landscape and cultural heritage. This work introduces a novel geological landscape and stone heritage map of the Genoa Walls Urban Park (1:10.000 scale). The park is located in the immediate surroundings of Genoa city centre and it includes a complex system of historical fortifications. Today the park is frequented by hikers, mountain bikers and tourists. The map shows three different elements of the park: lithological and geomorphological elements, cultural and landscape heritage sites and the trail network. This map offers new insights into the way in which the park authority can promote the sustainable fruition of a highly valuable area, characterised by landscape and historical interest next to one of the largest historical centres of Europe, part of which is inscribed in the list of Unesco World Heritage Sites

Implementation of Nature-Based Solutions for Hydro-Meteorological Risk Reduction in Small Mediterranean Catchments: The Case of Portofino Natural Regional Park, Italy

Nature-based solutions (NBS) are usually defined as complementary or alternative solutions to \u201cgrey infrastructures\u201d (traditionally made with cement) aimed at conserving and regenerating the functionality of natural and semi-natural ecosystems. The research to date shows a considerable potential of NBS to address the current challenges related to climate change and geo-hydrological risks. Despite significant interest in NBS by researchers and practitioners, knowledge concerning their practical implementation, monitoring, and evaluation is still lacking. This is particularly true for large-scale NBS. The present paper discusses how such solutions can be implemented in the context of hydro-meteorological risk reduction in small Mediterranean catchments with a strong tourist vocation. The work presented here is situated within the RECONECT Project (Regenerating ECOsystems with Nature-based solutions for hydro-meteorological risk rEduCTion), which aims to contribute to a European reference framework on NBS by demonstrating, upscaling, and replicating large-scale NBS in rural and natural areas. The Italian case study of RECONECT is the Portofino Natural Regional Park, which represents a unique natural landscape element with high ecologic, social, and economic (touristic) value, which is threatened by a range of geo-hydrological hazards, such as flash floods, hyper-concentrated floods, shallow landslides, rockfalls, and storm surges. This paper also presents details of NBS interventions in two pilot catchments (San Fruttuoso and Paraggi) visited by thousands of tourists throughout the year. It addresses some of the key aspects related to monitoring meteorological and hydrological processes, as well as remote sensing activities (i.e., LiDAR surveys), which are necessary for the identification of critical-instability areas along waterways and the reconstruction of dry stone walls. Lastly, a discussion of relevant mitigation and adaptation strategies that are potentially replicable at national and international levels is also provide

Geomorphological Landscape Research and Flood Management in a Heavily Modified Tyrrhenian Catchment

Since the nineteenth century, most urban catchments in Europe have been subject to significant landscape variations. These modifications have been caused by population change and the transition through rural, industrial and post-industrial economies. Land use and rainfall regime changes, together with land use variations, are frequently associated with flood hazard increase. This paper examines geomorphological landscape changes from the nineteenth century to the present day in the Bisagno Valley, Genoa metropolitan area. The Valley is internationally known for its recurring floods: the last events with fatalities occurred in 2011 and 2014. The extent of landscape change and the history of floods were examined by combining scientific data and information from historical maps, written accounts, topographical drawings and photographs. Historical–geographical and geomorphological analyses were used to reconstruct the runoff for three different periods since 1850. Our results demonstrate that geomorphological landscape variations, including modifications of the river bed, and the abandonment of the countryside and terraces are not sustainable and have progressively allowed an increase in flooding, making it necessary to implement sustainable management policies. In particular, specific spatial urban planning and management measures are necessary in order to mitigate flood hazard and vulnerability