86,615 research outputs found
Flash Flood Events and Urban Development in Genoa (Italy): Lost in Translation
No full textCoastal locations in the Mediterranean area experienced several geo-hydrological events from the beginning of the 3rd Millennium. Among the most flooded areas featuring the Ligurian coastal environment, Genoa is sorrowfully at international level, for the flash flood characteristics and consequent damage: the last event of 4 November 2011, once again, caused the loss of human lives. Genoa, in fact, can be considered an interesting case study for geo-hydrological risks: it can be said that to a general trend of increasing hazard, due to global and particular climate changes of the Mediterranean area, corresponds an increase of the vulnerability due to the urban growth on the flood plains. In this paper are analyzed the unusual meteorological characteristics of the Gulf of Genoa, the changes in the rate of daily precipitation using the recorded data at the station of Genoa, in use since 1833. The most significant periods of the land urban development are also briefly described. They have determined important changes of the territory, modifying the water balance of the basins in a considerable wa
Flood-induced ground effects and flood-water dynamics for hydro-geomorphic hazard assessment: the 21–22 October 2019 extreme flood along the lower Orba River (Alessandria, NW Italy)
No full textThe knowledge of flood-induced ground effects and flood-water dynamics is a crucial issue for hydro-geomorphic hazards assessment and mapping, and thus for river management and land use planning. This paper and the related 1:15,000 map illustrate the lower Orba River (NW Italy) and its adjacent floodplain geomorphic response to the 21 –22 October 2019 extreme flood.
This was estimated to be a 500-years flood and caused severe damage to cultivated fields, structures, and infrastructures. The research is based on extensive post-flood field surveys, ante- and post-flood GNSS surveys, and aerial photographs interpretation. Intense inchannel sediment mobilization, bank retreats, and channelization structures collapses were surveyed. Furthermore, alluvial gullies, overbank deposits, crevasse splays, and surficial-erosion evidences were mapped over the floodplain, along with the flooded area (17.65 km2) and the flood-water features. A specific legend developed for flood-related and anthropogenic elements mapping in a typical lowland agricultural landscape with regulated rivers is propose
Torrential floods in the upper Soana Valley (NW Italian Alps): Geomorphological processes and risk-reduction strategies
No full textThis paper investigates two severe floods that occurred in the upper Soana Valley (NW Italian Alps) in September 1993 and October 2000. In both events, intense rainfall triggered violent inundations along the Soana stream and its lateral creeks, producing extensive damage to several small urban areas along the riverbeds. Comparing these two very similar flood events, which occurred 7 years apart, we tried to understand the reasons why the new remediation implemented along the riverbanks after the first flood of 1993 failed to protect houses and infrastructure during the flood of 2000. Numerous field surveys have been carried out since the flood of October 2000 to gather information about the instability on the slopes and along the streams as well as to assess damage
to the built environment. Physiography, geomorphology and land-use analyses were also performed using multitemporal aerial photographs and old maps. Additional information was collected using historical archives. The results highlight that land-use decisions, in particular urban planning and management that occurred in the 1960s and 1980s, along with design flaws in the flood defence infrastructure, in particular the rip-rap and reins built after the 1993 event, were responsible for the many collapses and damage suffered during the flood of 2000. An issue with such remediation projects is the wrongly held belief that these structures are perfectly adaptable to the typology and location in any geomorphodynamic context, regardless of the characteristics of the
basin and watercourse
Fig. 2. – Living plants. A in A synoptic revision of the Malagasy endemic genus Socratina Balle (Loranthaceae). Candollea 69: 65-73. In English, English and French abstracts.
No full textFig. 2. – Living plants. A. Socratina keraudreniana Balle; B. S. bemarivensis (Lecomte) Balle; C. S. phillipsoniana Callm. & Luino. [Photos: A: J. Bosser; B: F. Ratovoson; C: I. Luino]Published as part of Callmander, M. W., I. Luino, S. Da-Giau, C. Rakotovao & L. Gautier, 2014, A synoptic revision of the Malagasy endemic genus Socratina Balle (Loranthaceae). Candollea 69: 65-73. In English, English and French abstracts., pp. 65-73 in Candollea 69 (1) on page 69, DOI: 10.5281/zenodo.16113
Dam failures in the 20th century: nearly 1,000 avoidable victims in Italy alone
No full textThe frequency of large dam failures all over the world, with a high toll of lives lost, pinpoints the still unsolved problems of risk resulting from the presence of large dams in built-up areas. Some of these failures and other related incidents took place in Italy in the past century. This paper discusses the three worst cases of dam failures occurring in Italy, analyzing the causes which led to collapse. They are the dams of Gleno (1923), Molare (1935) and Stava (1985)
Exposure to geo-hydrological hazards of the metropolitan area of Genoa, Italy: A multi-temporal analysis of the Bisagno stream
No full textGeo-hydrological 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-hydrological risk. Recent studies on Genoa's geo-hydrological hazard have focused on the analysis of hydro-geomorphological 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 geo-hydrological 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 "Bisagno Master Plan", a territorial planning strategy aimed at reducing geo-hydrological 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 decades
Deep Seated Gravitational Slope Deformations in a Ligurian Apennines catchment (Italy): evidences, characterizations and consequences
No full textThe Upper Scrivia Valley in the Ligurian Apennines is characterized by a large-scale landslides area wider than regional and national averages. A number of deep-seated gravitational slope deformations (DSGSDs) were detected and mapped on the basis of geomorphological constraints such as closed depressions, trenches, double ridges, counterscarps and para-karst formations. The DSGSDs make up about 10% of the area studied. The majority of large, paleo-and active landslides spread out within these DSGSDs and processes due to gravity are the main geomorphological issue. DSGSDs were distinguished according to geological and geo-mechanical features of rock masses into six case studies. Each case study represents different slope dynamic and exhibits its own geomorphological features. These case studies can be a valuable model for the study of DSGSDs within the Apennines.
The authors hypothesize as a factor of main trigger a phase of gravitational instability related to the evolution of the Ligurian-Adriatic watershed and a deepening of the erosional base levels set up at the end of the Pleistocene. The reasons are: i) the distribution and the geological and tectonic characteristics of the case studies, ii) the geomorphological conditions of this sector of Apennines, iii) the absence of a glacial withdrawal phase and iv) the low seismicity. The massive presence of DSGSDs raises important implications for geological cartography, land planning and monitoring because of the extent and kinematics of these phenomena. 
Man-made Terraces: From Ancient Anthropic Landscape Modification to Value at Risk. The Example of Cinque Terre and Portofino, Italy
No full textMan-made terraces for agricultural purposes are a quite diffuse and ancient anthropogenic landscape modification in mountainous areas. The original slope alteration, obtained through a sequence of sub-vertical and sub-planar surfaces, represents a human interference with the geomorphic system, altering the original balance of geomorphological and geo-hydrological factors. Stone walls and soil formed by human activity have been artificially immobilized on the slopes and are available again to gravitative processes once in abandonment and may be subject to deep degradation in case of intense rain events. However, socio-economic conditions play often a crucial role in the abandonment of terraces, indirectly contributing to increase gully erosion and walls failure. The modification of the original slope profile, due to its regular geometry in respect to the typical more complex natural surface, is rather suitable to be detected through remote sensing, particularly LIDAR, as many authors have recently demonstrated. In the present research the attention has been focused on the assessment of terraces and of the volume of stones and soil that have been involved by human activity. The research area is among the most deeply modified by terraces in the Mediterranean area and internationally famous for this landscape anthropogenic alteration: The Cinque Terre in Italy is a National Park intensively visited by tourists all over the year. Then terraces represent an important economic asset that need to be preserved from degradation and collapse as partially occurred in 2011 after the intense rain event that caused flood, hundreds of landslides and consequently damage. During the 2011 event many terraced slopes have collapsed with significant loss of soil and stone walls: the research allowed to evaluate the lost volumes and to estimate the remaining ones in the Vernazza catchment
Recent and historical maps as a tool to identify the flood prone zones and the riskiest urbanized areas along the Mediterranean floodplains (Italy)
No full textThis research deals with the use of historical cartography as a key tool for identifying flood risk areas for flash floods and consequently also for assessing the increase in the vulnerability of urban areas in the Mediterranean area. In recent years, there has been an increase in flash floods caused by intense and short-term rainfall: this may be related to climate change. But it is undoubtedly also due to inadequate territorial planning that has made it possible to construct buildings and infrastructures in hazardous areas very close to the riverbeds.
There has been an analysis of the current, recent and historical cartographic maps of the Italian urban areas of Genoa, Savona and Chiavari in Liguria, Cagliari and Olbia in Sardinia, Carrara, Grosseto and Livorno in Tuscany. A preliminary research has been then extended also to the cities of Nice in Provence-Alpes-Côte d'Azur (France) and Valencia (Spain). These are all cities built over time on floodplains that have experienced catastrophic flooding in recent decades.
Map comparisons from the nineteenth century to the present day have allowed us to reconstruct the morphological evolution of these urban areas. The hydrographic network in all the cases has undergone modifications, deviations and through the construction of walls and levees there has also been a progressive reduction in the width of the riverbed often connected to putting watercourses in culverts.
Other widespread changes concerned the construction of settlements and infrastructures in depressed and swampy areas in recent years, and the modification of the coastline due to landfill and transport. The serious events that have occurred in recent years have highlighted how the effects of flooding have been amplified by human interventions and structures built in the floodplains
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