U.S.- Italy Research Workshop on the

Hydrometeorology, Impacts, and Management of Extreme Floods

Perugia (Italy), November 1995







Enrico Marchi, Giorgio Roth, and Franco Siccardi

Istituto di Idraulica

Universita di Genova

Via Montallegro 1, 16145 Genova




     This paper discusses the major features of the Po River basin and the actions undertaken to mitigate the effects of extreme flood events specially those related to the 1994 disastrous flood event.  The river drains the largest morphological unit of the Italian territory.  River training works started in the Lower Po during the Roman Age and developed upstream, first as discontinuous systems, then connected to form two uninterrupted belts, which have reduced the overflow frequency but also the carrying capacity of the river channel.  The outcome has been increasing values of flood peak quantiles in the Lower Po, which is the reach with the highest risk of flooding.  On the other hand, the upstream catchment, where partial embankments are available, experienced recent flooding events, including that of November 1994, and requires protection.  The risk mitigation policy designed by the Italian National Department of Civil Protection, takes into account all the components of the river system.  It is clear that the development of traditional structural protection along the Po River has reached a critical stage; a further expansion of the existing levee system will increase the downstream flood risk.  Furthermore, it appears that non-structural measures, such as the coordination of the existing flood warning systems, may be suitable for protecting communities that are affected by such food occurrences along the Po River.  In addition, a reduction of the flood discharge entering the Lower Po is needed in order to decrease the risk of flooding to acceptable levels.  This paper shows that this goal can be accomplished only by diverting the higher part of the flood from the river immediately upstream of the Lower Po, allowing the inundation and the temporary storage of the diverted water on pre-designed large agricultural areas.  Implementing such a policy will require a reliable flood warning system and, above all, a sound regulatory authority.