Extreme Po River flood in November 1951 and inundation of Polesine territory (Northern Italy)

In November 1951, continuous and intense precipitations over the whole Po River basin triggered high flood levels in almost all alpine and apennine tributaries: the successive coincidence of flood wave coming from the Po and those coming from its tributaries caused rapid and notable increase to water level along the main river. Downstream from Ticino River confluence (basin area 37 000 km(2)) the floodwater, controlled by continuous main levees, reached higher levels than any previous maximum observed at all gauging stations. Near Pontelagoscuro (basin area 70 00 km(2)) the left main levee collapsed by water continuous overtopping, lasting for about 20 hours; through three large failures the overflowing water submerged in 11 days some 1 000 km(2) of Polesine territory, as far as the Po delta. Way and time of floodwater spreading towards the sea are frequently controlled by road or railway earthfills and by embankment of secondary hydrographic network.