1,720,965 research outputs found
Terraced landscape as cultural and environmental heritage at risk: an example from Portofino Park (Italy)
No full textMan-made terraces represent both a cultural and environmental asset. This important human modifi cation has
determined changes in the original balance of geomorphological and geo-hydrological factors, representing a human
interference with the geomorphic system. The abandonment of lands, according to altered socioeconomic condi-
tions and climate change determine an increase of erosion and geomorphological risk. Terraces on the slopes of the
Bay of San Fruttuoso di Camogli, in Portofi no Park (Italy), have been analysed through historical, social and eco-
nomic research, cartographic and photographic analysis, geomorphological fi eld surveys, meteorological-climatic
analyses and modelling of sediment yield with the aim to address management and mitigation of ris
Man-made activities and morphological changes of Ligurian floodplains (Italy) since modern history to nowadays: an approach through old maps comparison
No full textThe Tyrrhenian slope of Liguria extends along the coast, from West to East, for nearly 300 km between Ventimiglia to Marinella di Sarzana: this stretch of territory presents more than a hundred catchments mainly characterized by small-size floodplains, usually less than 1 km2. Ligurian catchments, except for the Roja and the Magra rivers, have common features: by the area they can be distinguished in small basins (less than 15 km2), medium (15-150 km2) and large (150-500 km2). The slopes of the catchment areas are very steep, while the flat alluvial plains are typically narrow and elongated: the largest one are referred to the Entella stream (approximately 4 km long) and the Centa stream (about 7 km in length). On these floodplains are located almost Ligurian urban areas, which represent the expansion of the historical settlements and road connections. Through a comparative mapping it was rebuilt the morphological evolution of Ligurian floodplains in historical times, witnessing the land-use and riverbed changes in the modern era until today, by using: 1) Historical maps of the eighteenth century by Matteo Vinzoni (“Pianta delle due riviere della serenissima Repubblica di Genova divise nei commissariati di sanità” e “Il Dominio della Serenissima Repubblica di Genova in terraferma”); 2) historical topographic maps of the first half of the nineteenth century (“Stati Sardi di Terraferma), in different topographic scales: a) 1:50.000, b) 1:20.000 and c) 1:9.450; 3) historical topographic maps of the second half of the nineteenth century until the first half of the twentieth century (“Tavolette dell’Istituto Geografico Militare Italiano, Firenze, 1878-1940, 1:25.000); 4) regional maps for the second half of the twentieth century, 1: 10.000 and 1: 25.000, while the current status was assessed with Google Earth Pro platforms; 5) important information was taken by the Map of the historical evolution of urban fabric, 1: 50.000 produced by Liguria Region and obtained by the overlap of urbanized areas in different periods (1855, 1936, 1964 and 1986). The secular human activities have therefore modified the natural landscape through land use changes, either for catchment or for the floodplain. The main channel, and even the minor hydrographic network, have showed major transformations over time. The anthropic action has deeply modified the morphology of Ligurian floodplains, except for the two largest: Albenga (Centa stream) and Chiavari-Lavagna (Entella stream), which still have a portion of soil for agricultural purposes. In many cases it has detected a river-bed covering, especially in the medium-terminal portion, for the purpose of building needs and the road link. Other very widespread changes finally concern: a) deviations and displacements of the riverbed, b) the progradation of the coastline due to fills and embankments
The role of historical agricultural terraces in geo-hydrological risk reduction: a case study from the Bisagno Stream catchment (Genoa, Italy)
No full textTerraces, traditionally sustained by dry stonewalls, occupy about thirty percent of the territory of Liguria. If constantly maintained, they effectively contribute to slow down the natural slope erosion. When no longer managed, terraces are recognized as one of the reasons for increased geomorphological risk along the slopes and, consequently, at the bottom of the valley. ThisstudyconcernstheterracedlandscapesoftheBisagnoStreamcatchment,internationallyknownfortherecent and recurring floods which affected the city of Genoa. The Bisagno Stream catchment is an example of historical evolution of the territory both in terms of land use change and geo-hydrological risk. The catchment, whose highest point is Mount Candelozzo (1034 m), has a total area of 95 km2. In its terminal stretch the stream flows across the eastern part of Genoa city centre. It is a typical valley of the Genoa metropolitan area, with steep slopes and short times of concentration. Here the signs of the tragic floods which have affected the area since 1970 are still visible. The most recent and tragic geo-hydrological event in Liguria took place in the Bisagno Valley in October 2014. The study was carried out with a multi-temporal comparison of the terraced areas using aerial photographs and regional cartographic information. A further step will involve the analysis and classification of the terraces based ontheirmaintenanceconditionandhydrogeologicaleffectiveness,usingsomerepresentativeareasofthevalleyas cases study. The comparison between the distribution of terraces in the Bisagno valley and applied geomorphological cartography suggests the need of measures to reduce the risk according to a suitable set of priorities, including the recovery of the terraced areas and connected structures aimed to limit the accumulation of solid material along the main waterway
Increased flash flooding and climate change in the Genoa Metropolitan Area (Italy)
No full textThe Genoa Metropolitan Area (GMA) is historically affected by flash floods for two main reasons: the meteorological conditions due to the Genoa Low and the city’s geomorphologic arrangement: a narrow coast belt bounded by mountains. In the last years in GMA there is also an increase in flash floods due to man-made landforms and changes in rainfall regime. In 2014 several floods took place: in some areas of the hinterland the cumulate year rainfall has exceeded 4000 mm, while 2000 mm fell on the coast. The research analyses the thermo-pluviometric statistics collected over more than 100 years, registered by Genoa University (since 1833) and Chiavari (since 1877) stations, which represent the central and the eastern zone of the GMA. An analysis was based on mean annual air temperatures, rainfall, rainy days and rainfall rate, which means an annual rainfall and rainy days ratio. The air temperatures show a positive trend, statistically significant, rising from an average of 15 °C in the 19th Century to a current average of 16° C. The annual rainfall does not show any trend, remaining at an average of 1270 mm for Genoa and 1180 mm for Chiavari [5]. The number of rainy days shows a negative trend, statistically significant, from more than 110 days in the 19th Century in Genoa (90 in Chiavari) to 90 nowadays (80 days in Chiavari). As a consequence, the rate of daily rainfall shows a positive trend: we can say that rainfall is more intense. The scenario above is confirmed by the analysis of maximum precipitation recorded by the two pluviographs for 1,3,6,12 and 24 hours in 1945-2014 period; although there is no statistical relevance, all the analyzed values indicate an increasement over time, showing the intensification of flood events in recent decades
Human-induced landscape changes and geo-hydrological risk: the Rupinaro catchment, Liguria, Italy
No full textSmall and steep watersheds are typical of Liguria, northern Italy. In these small watersheds, geo-hydrological hazards,
including flash floods and shallow landslides, caused by high intensity rainfall are frequent and abundant. In
the coastal valleys of Liguria, narrow flood plains have hosted human settlements and communication lines since
the protohistoric period. Since then, a variety of human activities have modified the natural landscape significantly,
and chiefly through land-use changes first in the flood-plains, and next along the slopes. We have studied the 11-
square km Rupinaro catchment, west of Chiavari, which has been inhabited since the 8th century BC. Progressive
human actions have modified the main river and its tributaries, which have become narrower and canalized, and locally
they were covered completely. Human actions have also contributed to the increase in the runoff coefficients,
and to the progradation of the main river into the Ligurian Sea. Demographic growth, socio-economic development
and urbanization are the main drivers for the land use changes occurred in the Rupinaro catchment. Through
a combined analysis of archaeological and palynologycal data, and the multi-temporal analysis of historical maps,
aerial photographs and satellite imagery of different vintages, we have reconstructed phases of modifications of
the river and the tributaries. We determined the land use changes calculating the loss of soil, analyzing statistics of
buildings and demography for the last 150 years, and interpreting historical maps and aerial and satellite imagery.
We found that land reclamations, the construction of embankments, and the rectification of rivers are the main
human actions performed to obtain building areas along the main river course. Expansion of urban settlements in
flood prone areas, and even in the main riverbed, have reached a critical limit has shown by the destructive flood
event that has affected the Rupinaro catchment, and chiefly the town of Chiavari, in November 2014
The 10th November 2014 flash-flood event in Chiavari city (Eastern Liguria, Italy)
No full textDue to short durations of heavy rainfalls that occurred between November 10th and 11th, 2014 the Chiavari area was the subject of a serious geo-hydrological event determined by the simultaneous overflowing of the Entella and Rupinaro streams.
In the lower Fontanabuona valley (Municipality of Leivi) a landslide destroyed a building and took the lives of two people, while severe damages to buildings and infrastructures were recorded in the Chiavari historical center, Carasco and Cogorno.
Between 08:00 am on November 10th and 08:00 am on November 11th 2014, peaks of rainfall peaks in Entella stream catchment order of 60 mm/1h and cumulated rainfall of 220 mm/24h were recorded. The levels of streams were immediately elevated, highlighting a concentrated time of less than 1 hour between 08:00 pm and 00:00 am when the level of the Entella stream moved up to 7 m leading to the flooding in Carasco, Cogorno, and in Chiavari (the Caperana district). Meanwhile flash flooding in the Rupinaro stream resulted in water levels up to 1.5 m in the old town of Chiavari
Terraced slope on active coastal landslides. The case of Le Grazie hill (Genoa Metropolitan Area, Italy)
No full textUncontrolled urbanization and Geo-Hydrological hazard in the Ligurian catchments: a case study from the Rapallo floodplain
No full textChanges in rainfall regime and geo-hydrological events: an example from Chiavari City area (Eastern Liguria, Italy)
No full text
- …
