In the last ten years, the Abruzzi region was affected by several heavy rainfall events. Almost three of them have had daily rainfall > 100 mm and >200 mm in few days. In this work the heavy rainfall events occurred on 23-25 January 2003 (in the whole region), on 6-7 October 2007 (in a small part of the hilly and coastal Teramo area), and on 1-2 March 2011 (in the hilly and coastal Teramo and Pescara area). These events have triggered different types of geomorphological instability: landslides, soil erosion, flooding. Distribution and types of instabilities and landforms is almost different in the three cases. In this work the 2003, 2007 and 2011 heavy rainfall events were analyzed concerning meteorological aspects, geological and geomorphological features, highlighting common and different geomorphological effects on the landscape. Heavy rainfall were analyzed processing a >40 pluviometric station database provided by Servizio Idrografico e Mareografico (Direzione Protezione Civile e Ambiente, Regione Abruzzo) including daily and monthly historical data (30-70 years) and 5-15 min pluviometric registrations for at least six days around the main events. The data processing enabled the analysis and comparison of hourly rainfall intensity, cumulative rainfall, daily rainfall, monthly rainfall and previous month rainfall. Geomorphological effects of heavy rainfall were analyzed through field surveys, aerial photo analysis, and inventories or technical reports, mapping the distribution of landslides, soil erosion, flooding. The 2003 heavy rainfall event affected the almost entire region (Chieti and Pescara province and part of L’Aquila and Teramo), for almost 72 h, with moderately high intensity (~10-15 mm/hr, 80-120 mm/day), high cumulative rainfall (up to >200 mm), occurred after two month of high rainfall, on a poorly vegetated landscape due to the winter season. These features induced heavy flooding within the main alluvial plains and triggered ~1300 landslides from small to very wide, whose distribution was controlled mostly by lithology (91% on clay-sand deposits, 2% carbonate rocks and 7% on clastic Quaternary continental deposits) and by structural geomorphological setting. The 2007 heavy rainfall event affected a local area (hilly and costal Tortoreto area between F. Salinello and T. Vibrata within the Teramo province), for a short time (14-16 h), with high intensity (10-40 mm/hr, up to >200 mm/day), high cumulative rainfall (up to 230 mm), occurred after two month of low rainfall, on a very poorly vegetated landscape, particularly on agricultural areas (arable land, vineyard and olive groves) due ploughing. These features induced heavy soil erosion processes on slopes, rapid earth flows at the base of slopes or minor drainage basins, and flooding within the main alluvial plains, mostly due to minor tributary drainage basins. This is also controlled by the structural geomorphological features of the radial drainage pattern, incorporating the coastal streams and tributary streams of the lower valleys of F. Salinello and T. Vibrata. The 2011 heavy rainfall event affected a province area (hilly and costal Teramo area), for a moderately short time (22-26 h), with high intensity (~15-35 mm/hr, up to 180 mm/day), high cumulative rainfall (up to 230 mm), occurred after two month of moderate rainfall, on a moderately vegetated landscape on agricultural areas (arable land, vineyard and olive groves) due to initial crop growth stage and grass development. These features induced moderate soil erosion processes on slopes and rapid earth flows at the base of slopes or minor drainage basins (less than 2007 event). The crop and grass cover promoted surface runoff directly to the main rivers, protecting slopes from soil erosion. Heavy flooding affected alluvial plains and coastal plains, due to both tributary and main rivers, with the formation of widespread crevasse splay. Also in this case runoff and flooding were increased by structural geomorphological features of the radial and trellis drainage pattern of the Teramo hilly area. This work allow to highlight that these type of methods, investigations, and data is basic in applied studies for stabilisation and management of slopes and minor or major drainage basins and for general land management. Only a high knowledge level of geomorphological instability, connected to drainage, geological-geomorphological, and morphostructural features and to meteorological events, particularly when joined to geotechnical data, allow effective stabilisation and management plans. Finally, these type of studies is basic and complementary to recent methods for investigation and mapping of land sensitivity to geomorphological processes such as landslides, soil erosion, desertification, etc., and allow to define future scenarios, which sustainable land planning and management should be based on, taking into account specific destination of different areas, and contributing to identify proper sites for quarry, dump, purification plant, etc., or proper areas for industries, urban expansion, or in general to support the process of creating an urban plan.
Il dissesto geomorfologico indotto dalle precipitazioni negli eventi meteorici critici degli ultimi dieci anni in Abruzzo (Italia centrale).
MICCADEI, Enrico;PIACENTINI, Tommaso;
2011-01-01
Abstract
In the last ten years, the Abruzzi region was affected by several heavy rainfall events. Almost three of them have had daily rainfall > 100 mm and >200 mm in few days. In this work the heavy rainfall events occurred on 23-25 January 2003 (in the whole region), on 6-7 October 2007 (in a small part of the hilly and coastal Teramo area), and on 1-2 March 2011 (in the hilly and coastal Teramo and Pescara area). These events have triggered different types of geomorphological instability: landslides, soil erosion, flooding. Distribution and types of instabilities and landforms is almost different in the three cases. In this work the 2003, 2007 and 2011 heavy rainfall events were analyzed concerning meteorological aspects, geological and geomorphological features, highlighting common and different geomorphological effects on the landscape. Heavy rainfall were analyzed processing a >40 pluviometric station database provided by Servizio Idrografico e Mareografico (Direzione Protezione Civile e Ambiente, Regione Abruzzo) including daily and monthly historical data (30-70 years) and 5-15 min pluviometric registrations for at least six days around the main events. The data processing enabled the analysis and comparison of hourly rainfall intensity, cumulative rainfall, daily rainfall, monthly rainfall and previous month rainfall. Geomorphological effects of heavy rainfall were analyzed through field surveys, aerial photo analysis, and inventories or technical reports, mapping the distribution of landslides, soil erosion, flooding. The 2003 heavy rainfall event affected the almost entire region (Chieti and Pescara province and part of L’Aquila and Teramo), for almost 72 h, with moderately high intensity (~10-15 mm/hr, 80-120 mm/day), high cumulative rainfall (up to >200 mm), occurred after two month of high rainfall, on a poorly vegetated landscape due to the winter season. These features induced heavy flooding within the main alluvial plains and triggered ~1300 landslides from small to very wide, whose distribution was controlled mostly by lithology (91% on clay-sand deposits, 2% carbonate rocks and 7% on clastic Quaternary continental deposits) and by structural geomorphological setting. The 2007 heavy rainfall event affected a local area (hilly and costal Tortoreto area between F. Salinello and T. Vibrata within the Teramo province), for a short time (14-16 h), with high intensity (10-40 mm/hr, up to >200 mm/day), high cumulative rainfall (up to 230 mm), occurred after two month of low rainfall, on a very poorly vegetated landscape, particularly on agricultural areas (arable land, vineyard and olive groves) due ploughing. These features induced heavy soil erosion processes on slopes, rapid earth flows at the base of slopes or minor drainage basins, and flooding within the main alluvial plains, mostly due to minor tributary drainage basins. This is also controlled by the structural geomorphological features of the radial drainage pattern, incorporating the coastal streams and tributary streams of the lower valleys of F. Salinello and T. Vibrata. The 2011 heavy rainfall event affected a province area (hilly and costal Teramo area), for a moderately short time (22-26 h), with high intensity (~15-35 mm/hr, up to 180 mm/day), high cumulative rainfall (up to 230 mm), occurred after two month of moderate rainfall, on a moderately vegetated landscape on agricultural areas (arable land, vineyard and olive groves) due to initial crop growth stage and grass development. These features induced moderate soil erosion processes on slopes and rapid earth flows at the base of slopes or minor drainage basins (less than 2007 event). The crop and grass cover promoted surface runoff directly to the main rivers, protecting slopes from soil erosion. Heavy flooding affected alluvial plains and coastal plains, due to both tributary and main rivers, with the formation of widespread crevasse splay. Also in this case runoff and flooding were increased by structural geomorphological features of the radial and trellis drainage pattern of the Teramo hilly area. This work allow to highlight that these type of methods, investigations, and data is basic in applied studies for stabilisation and management of slopes and minor or major drainage basins and for general land management. Only a high knowledge level of geomorphological instability, connected to drainage, geological-geomorphological, and morphostructural features and to meteorological events, particularly when joined to geotechnical data, allow effective stabilisation and management plans. Finally, these type of studies is basic and complementary to recent methods for investigation and mapping of land sensitivity to geomorphological processes such as landslides, soil erosion, desertification, etc., and allow to define future scenarios, which sustainable land planning and management should be based on, taking into account specific destination of different areas, and contributing to identify proper sites for quarry, dump, purification plant, etc., or proper areas for industries, urban expansion, or in general to support the process of creating an urban plan.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.