«Per mezza Toscana si spazia un fiumicel che nasce in Falterona e cento miglia di corso nol sazia»
(Dante Alighieri, Divina Commedia, Purgatorio, Canto XIV)
The Arno river is an element that strongly characterizes the Tuscan landscape, starting from its source on the south-west side of the Monte Falterona until its outlet into the Mar Ligure. Beside having shaped over the time the natural forms such as valleys and plains, it has determined the presence of human activities and of cities such as Florence and Pisa, whose history is indissolubly linked to the river.
The Arno’s story
With its 241 kms the Arno is the eighth italian river in length. It presents a torrential flow, with low water in Summer and tumultuous overflows in Autumn, that in the past caused disastrous floods, such as the tragic flood in 1966 that caused serious damages in Florence as well as in Pisa.
In the last part of its course the Arno is characterized by a very low decline and by a slow flow, that determines the sinuous course and the creation of many bights. The bights are natural meanders of the river that, slowing down the discharge of the water, contribute to make it flood on occasion of the big overflows, submerging the surrounding lands.
In the past, to make the Arno overflows less dangerous, the river was strongly regulated and its natural course was modified many times. Especially, during Cosimo I de Medici’s government (1519-1574), many bights were eliminated and, at the same time, the reclamations of the swampy lands close to the river began. The dam caused the increasing of the flow rate of the river and consequently the erosion of the riverbed and the shores.
The river itself, transporting the eroded materials, determined an enormous sedimentary accumulation. The so-called Piana di Pisa is an alluvial plain created recently: during the Roman times, in fact, Pisa was equipped with a sea harbor, while today the port of the Marina di Pisa is about 8 kms from the city. After many interventions, also the Serchio river, that originally flowed into the Arno with its main branch, has been subjected to modifications of its course and today it flows directly into the sea, north but not far from Bocca d’Arno.
Over the centuries all Tuscany has been subjected to intense reclamation works of the swampy lands, often flooded during the overflows of the rivers and streams, through the reinforcement and the raising of the river banks. The elimination of these natural flooding basins had as a consequence the progressive increase of the river flow intensity, that caused the erosion of the riverbed along the entire length until the outlet. In this way, the coast sea bottom has increased its depth, not allowing the sedimentation and so the growth of the beach. This phenomenon has caused the progressive erosion of the coast, which is still ongoing.
Our ideal itinerary starts from the torrent Zambra in Calci, which has its source on the Monte Pisano and descends along the Val Graziosa to flow into the Arno at the hight of the village of Zambra. Once it was called Valle Buia, the Val Graziosa was called like this by the Chartusian friars who, in 1366, founded the Chartreuse of Pisa in Calci, today it is the seat of the Museum of Natural History of the University of Pisa.
Passed the village of Zambra the river goes through the plain with wide meanders; in the interior of one of these there are the Lakes of Campo, two artificial basins created after the extraction activity for the production of bricks. Nowadays, the lakes have been re-naturalized and are usable thanks to a didactic path provided with informative panels.
After having flanked the Piagge area, the rived crosses the historical center of Pisa, where its course is very regulated and cemented. In its last part the Arno runs through the Parco Regionale di Migliarino San Rossore Massaciuccoli, which includes very interesting natural areas.
The current Bocca d’Arno has the position determined by the Ferdinando’s cut in 1606, when the outlet was moved northern to permit the discharge of the water. This movement originated Marina di Pisa where is the Tourist port of Pisa opened to the public on June 30, 2013.