A Flood Can Point Out Improper Land-Use Planning: The Case of Alessandria Town (Piedmont, Northern Italy)

The steady expansion of urbanized areas on the river banks has gradually taken away important spaces belonging to the hydrographic network. When a flood oc-curs with large overflowings the urbanized areas are inevitably inundated, some-times with victims and considerable damage. The flood occurred twenty years ago, at the beginning of November 1994, in Piedmont (northern Italy) has emphasized the vulnerability of many urban areas towards river-dynamics processes. More than one hundred towns were flooded and a huge amount of lives were lost: 69 in all, 50 of which directly caused by flooding. In the weeks that followed the flood event many surveys were carried out in the mostly damaged towns, with the goal to exactly define the flooded are-as, measure the levels reached by the water, survey the damage, interview people that was subjected to the flood. All information gathered allowed to better under-stand the flood dynamics. The surveyed data were then compared with the aerial photographs available and were completed by the investigation of historical records concerning past flood events, the analysis of the urban areas development and the survey of the man-made changes of the river beds occurred during the last two centuries. This allowed in many cases to understand the reasons behind the apparent increase of the urban areas vulnerability towards geo-hydrological processes. In this paper are presented the results obtained from a detailed study for Ales-sandria, provincial capital of Piedmont, important town along the Tanaro River.