Le calamità idrogeologiche dell'inverno 1995-96 nel territorio tarantino

Abstract

Throughout 1995 is most of the territory of Taranto, heavy rainfalls have followed dry years of infrequent precipitation. The trend has persisted for three more months in 1996, thus leading to multiple calamitous events. Between January and February 1996, many municipalities in the province of Taranto have been hit disasters due to such unprecedented rainfalls. Hydrologic events of various duration and intensity and altered climatic conditions have resulted in simultaneous disasters, namely river overflowing, water-logging, massive flooding, extensive landslides, intense erosions and severe damage to transport and water facilities. The hydrogeologic disasters were not triggered by the extraordinary amount of surface flowing water alone. Also underground water bodies, subject to significant recharge have increased spring water flows, somewhere acquiring an artesian attitude and thus steadily worsening the existing hydrogeologic emergency. A characterization of the newly arisen set of conditions has been atternpted by studying daily rainfall rates, peak annua1 precipitation lasting 1, 3, 6, 12 and 24 hours and temperature. The examination of the hydrogeologic disaster within an extended time frame has indicated the prominerzt role played by long lasting drought on the efficiency of the watercourse network and on the fragili01 of the territory. 1t follows that the drawbacks of different natura1 phenomena have overlapped in the Jirst three months of 1996 in the province of Taranto. Moreover; the effects of these phenomena have been occasionally enhanced by the irnpact of human activity unsuitable maintenance of the hydrographic network and poor contro1 over the territory. A true natura1 calamity has thus occurred which has brought about particularly severe situations in some areas where the risk of subsequent ydrogeologic disasters remains.