30 years have passed since the disastrous flood that 5 e The November 6, 1994 hit the provinces of Cuneo, Asti and Alessandria. Here the Tanaro river and its tributaries flooded due to particularly intense rainfall (up to 200 mm in 24 hours) occurred in the previous days, causing flooded roads, closed bridges and thousands of landslides. The Vercelli area was also affected, but in this case by the flooding of the Po river. Overall, the event caused a seventy deaths, thousands of displaced people And damages for approximately 20,000 billion lire. The 1994 flood was one of the most serious ever to occur in Piedmont and was the first real “test bed” of the National Civil Protection Service, established two years earlier. The event brought to light the importance of prediction and of prevention of hydrogeological risk.
The 1994 flood in Piedmont: the flood of the Tanaro
Between 2 and 6 November 1994, intense and continuous rainfall affected theLigurian Apenninesthe Langhe and the Monferrato. This weather event was not accurately predicted, since technologies at the time were not as advanced as they are today. The peak of rainfall was recorded in Ponzone, in the province of Alessandria, where a value of 54.8mm/h around midnight on November 4th. During the night the rains also spread to the Asti area and in the afternoon to the Biella area. In many places in the Tanaro, Bormida and Belbo basins the 200 mm of rain in 24 hours. The prolonged rainfall fed the waters of the Tanaro, whose flow rate increased until on the afternoon of November 5, at its upper course in the Ligurian Alps, the river overflowed and invaded some inhabited centers including Ormea and Garessio. The flood wave subsequently reached the localities downstream of Ceva, including Clavesana and Farigliano and continued towards Alba, Asti and then Alessandria, up to the confluence with the Po (where it arrived on 7 November).
During the flood the Tanaro reached exceptional flow values: in Farigliano, for example, it touchedheight of 9 m and the maximum range was 3400 m3/s. As it passed, the flood devastated the inhabited centers, inundating them and causing very serious damage and victims. Even a small stream like the Rea, a tributary of the Tanaro, violently invaded the territory of Dogliani and Monchiero, overwhelming cars and causing victims. At the same time, the intense rainfall crumbled entire slopes of the Langhe, causing thousands of landslides.
The area most affected by the event was province of Cuneowith 29 victims. The flood of the Tanaro modified the flow of the river: new branches were created and ancient abandoned meanders were reactivated. The flood affected the buildings of hundreds of municipalities and some inhabited centers remained isolated for several days. Many infrastructures were damaged or destroyed and traffic was compromised. Many bridges proved unsuitable for flood flow, often due to their spans being blocked by logs and other accumulated materials. In general, the lack of maintenance along the entire river course it contributed to determining the most serious consequences.
The alarm system today in Piedmont
A decisive role was that of incorrect territorial planningaccording to which areas subject to flooding during river floods were also built up. At the time, there was also a lack of an adequate monitoring and warning system: the victims were caught by surprise, especially along the streets and inside garages and cellars. Today, ARPA regularly issues much more accurate weather warning bulletins (due to progress in forecasting models) and citizens are more informed about the rules of conduct to follow in the event of events of this type: the active warning system in Piedmont, organized in part starting from the tragic events of 1994, it is managed by the Functional Center of Civil Protection of Piedmont, established in 2004, and provides for the activation of all the operational phases of preparation for the alert, the implementation of which is facilitated by full communication between institutional and non-institutional subjects and citizens. The 1994 flood was in some ways the first real emergency that the National Civil Protection Service, established in 1992, found itself facing.
The event brought to light the importance of prediction and of prevention of hydrogeological risk. Today, even though many steps forward have been made in this sense, we find ourselves facing the extreme weather events linked to ongoing climate change. These are often different phenomena compared to the prolonged rainfall of 1994, of much shorter duration and enormous intensity, capable of causing very serious damage despite the fact that we have much more advanced monitoring, warning and emergency management systems at our disposal.
