Reno (river)

Geography

It takes the name of Reno in the Province of Pistoia, to 745 m of altitude, where the two arms of the Reno di Prunetta (long of approximately 4 km, with its source with 1200m in the commune of Piteglio) and of the Reno di Campolungo are linked close to the locality of the Piastre of the commune of Pistoia. On this course in mountain, it marks the limit between the Emilie-Romagna and the Toscane and crosses a wild and timbered throat of 14 km, copiously sprinkled in each season, traversed by the Bologna-Porretta-Pistoia railway line which slips on the bottom of the valley with works of art (bridges, galleries, walls of support) representing a true chief of work of studies of engineering of the time of construction (1864). Very important for the communications between the North and the South of the Italy; emerging in the Flat of Po, it sprinkles Bologna and its metropolitan surface (here, with Casalecchio di Reno, it has a medium flow of 26 M ³ /sec, minimum of 2,6 m ³ /sec and maximum of 2 300 m ³ /sec); he traverses the flat rich person émilienne and, a little more to North of Cento, its course turns towards Is and the Adriatic Sea, or emerges with a Estuaire of 120 m width with close to the " Valli di Comacchio " in the Delta of Po.

Affluents

Affluents: Silla (18 km) and Samoggia (44 km) with the left; Limentra (28 km), Setta (47 km), Idice (80 km) (and its important affluent Sàvena - 54 km - which is the second river of Bologna, as points out Dante Alighieri in Divina Commedia , or the bolognaises are " color che stanno FRA Sàvena E Reno "), Sillaro (66 km), Santerno (the 103 most important km, also for its medium flow of 16 m ³ /sec, which sprinkles Imola) and Senio (92 km) on the right.

Its catchment area covers approximately 2 million people.

Water of Reno (and Savena) was used, as of the Moyen-âge, for the industry of silk in the town of Bologna with two channels (Canale di Reno E Canale di Savena).

Crossed cities

The Reno passes by Porretta Terme, Vergato, Marzabotto, Sasso Marconi, Casalecchio di Reno, Bologna, Cento, Argenta and leads in the Adriatique to the south-east of the Valleys of Comacchio (where it is connected to some channels of allowance), meadows of Torri di Bellocchio, with a vast estuary and a broad course of approximately 120 m with direction SN in the last 2 km, separated from the sea by sandy offshore bar.

Reno with the Middle Ages

During the papacy of Benoit XIV (the Cardinal bolognais Prospero Lambertini), the Reno river was prone to a fundamental hydraulic modification: after having been an affluent of Po in time of the Early middle ages, either all alone, or jointly with the Panaro, successive and periodic risings, causing devastation and silting in the countryside ferraraise and bolognaise. Vast marshy zone, antiquement named Valle Padusa (of Padus, Roman name of Po), which was unsuitable with the culture.

Reno was then diverted by the digging of an artificial channel of approximately 30 km, the Cavo Benedettino in direction of the Adriatic Sea and was connected with the old abandoned course of the Po of Primaro ( Po di Primaro ), representing consequently the current aspect, with flow characteristic initially of the south in north, then, after a sudden curve (close to the locality Sant' Agostino), of west with is, until the last way directed towards north after having wandered and having effleuré the Marshes of Comacchio (Valli di Comacchio) in the south of the Delta of Po.

In 43 av.JC. , on small an island of Reno, then Roman colony of Bononia (old name of Bologna), was stipulated the pact constitutive of the Second triumvirate. In the locality of Sacerno, in which according to the tradition this small island would have been, a column was set up at the XVIII century to point out the event

Course in mountain

Along its course it receives many affluents, all with torrential mode, some in temporary matter, others with character eternal.

The Reno , then, hardly left the throat with Ponte della Venturina, maintains until Vergato an average slope of the 0,8% and it receives, in the order: on the right Limentra de Sambuca, on the left Rio Maggiore in Porretta Term, and, shortly after this locality, the river Silla, which constitutes its major element.

With Riola di Vergato , after having to pass very close to celebrates it church projected by the Finnish architect Alvar Aalto (1898-1976), and after having received on its left the modest Marano torrent, it receives on its line the tumultuous torrent Limentra de Treppio, second affluent from its length.

With Vergato , from left, it still receives the modest Vergatello torrent with its Àneva affluent. Then still on its left, the Venola torrent and, before the Rock of Sasso Marconi, the Croaro torrent (or Croara). In Sasso Marconi, on its line, it receives the Setta (vast gravillonneux course from almost 1 km of width) with its affluents Gambellato, Brasimone and Sambro.

Course in plain

The mountain way finishes with the Lock of Casalecchio di Reno, approximately to 60 m of altitude. Downstream from this point, in addition, Reno changed several times its course, during the recent centuries (even by the hand of the man), but even at a moved back geological time, while being with being either tributary Po (only or linked with the Panaro), or succeeding at sea, or by finishing in marshes in the area of Ferrare, until being, like now and since the XVIII century half, the major collector, to the sea, of the plain émilienne-romagnole.

In the way in plain it receives on its left, downstream from Cento, only the Samoggia (with its Lavino affluent); while the greatest contributions come to him from four longer affluents, all of right-hand side, which are, in the order: the river Idice (with its affluents Zena, Savena, Centonara, Quaderna), the torrent Sillaro with its Sellustra affluent, river Santerno (its principal tributary for its length and its average flow of water to its junction) with its Diaterna affluent and, finally, river Senio with its Sintria affluent.

In the way of plain, moreover, it receives many channels of allowance of the plain bolonaise and ravennaise, partly even through the channel Navile and the channel of Savena , without forgetting the channel Riolo , the channel Lorgana , etc Starting from the junction of the torrent Sillaro to the mouth, it represents the historical and geographical border between Emilie and Romagna.

The Hydroelectric exploitation

The high basin includes/understands several stoppings with hydroelectric goal:

Basin of Molino del Pallone on Reno same (50.000 m3),
Basin of Pavana on Limentra de Sambuca (900.000 m3),
Basin of Suviana on Limentra de Treppio (43.850.000 m3),
Basin of Scalere or Brasimone, on the torrent Brasimone (6.390.000 m3),
Basin of Sainta Maria always on Brasimone (210.000 m3), almost all connected to each other by channels underground to gravity or systems of pumping of water, able each one of a flow of tens of cubic meters at the second.

The hydroelectric importance of the system and the output power (of the same order of magnitude of the large alpine hydroelectric basins) are second. In the Apennin, it was largely exploited by the State railways for the power supply of direct the Bologna-Florence; on the contrary, historically, the system of the stoppings was born mainly in the years 1930, just to this end and the power was increased appreciably in the years 1970 with the creation of the large Hydroelectric station of Bargi.

The hydraulic mode

The catchment area of Reno has a surface of 4.139 km, corresponding to the 18% of the whole physical surface of the Emilie-Romagna and to the 6% of this of the basin of Po. The surface of the basin of plain is equivalent to 1.542 km, while the portion mountain-hill extends in Apennin Tuscan-émilien-romagnol on a surface from 2.597 km. the pluviometric surge on the basin is, in averages, around 1.000 mm annual

With the outlet in plain (Casalecchio di Reno), the annual medium flow is of 26.5 m3/sec, while, towards the mouth, the annual medium flow is of 95 m3/sec.

The recorded maximum flows with Casalecchio di Reno effleurent the 2.300 m3/sec (2.290 in the risings with a 200 years flashback and 1.547 in the risings with a 30 years passing), but in the ordinary risings one exceeds little the 1.000.

In the way in plain, such values remain substantially, is by the intervention in the maximum coast, of the “fuller of Reno” (Cavo Napoleonico placed little beyond Cento, which, with a system of doors to the Léonard de Vinci pleads part of water with Po, if the hydraulic conditions of this last allow it), that is to say by the redistribution of “too full” with raw which occurs in the bed, even if the duration with raw lengthens by the addition of the many affluents and the intervention of the systems of pumping of the Consortia of Reno-Palata allowance. Each one of these risings being able to be able indeed to influence the contributions out of water, especially during the dry time.

The absolute minimal flow with the mouth is from approximately 4 m3/sec, while in Casalecchio it is of 0,6 m3/sec, but approximately a century ago it never went down under the 5 or 6 m3/sec. The full maximum ones are historically recorded in November, but the month when the medium flows are highest is Mars (52 m3/sec with Casalecchio, approximately 200 towards the mouth), while the month with insufficient medium flows is August (2.4 m3/sec with Casalecchio, approximately 8 towards the mouth). In Casalecchio the medium flow never goes down under the 20 m3/sec from October at May, while in July, August and September the values are lower than 10 m3/sec and, usually, they are directed in the Channel of Reno (then Canal Navile), by leaving this manner in summer the almost dry bed, at least until Cento.

The analysis of these values confirms before all the torrential character of the river, whose basin is established almost entirely on impermeable rocks and grounds (except some portions of mountain on the higher course of the river, both Limentra and Santerno) what explains the considerable amplitudes of the hydraulic mode. In addition, in the plain, around Castenaso, they exist some small resurgences of more negligible range.

The historical analysis of the values of mini flow (especially those of Casalecchio), moreover, confirms that the river, a time with flows minis absolutes of ten times higher than those current, due to the semipermeable grounds of its higher course and some of its affluents, undergoes an intensive exploitation on the mountainous way, with almost systematic collecting of the sources of its affluents: it is enough to observe that its major attribute, the Setta, at least during the three summer months is not to him of any contribution, since it is entirely collected by the Aqueduct of Bologna less than 1 km upstream of the junction.

For proof, it is enough to observe that approximately to 8 km of the mouth, in locality Volta Scirocco (in the immediate proximities of the Guiccioli farm, in locality Mandriole, where, on August 4th, 1849, Anita Garibaldi died, exhausted by its long escape), Reno is barred of a " transversale" (or mobile stopping) long of more than 120 m the purpose of which is to create, upstream, a fresh water tank with a free level of approximately 1,5 m, superior on that average of the sea, preventing the increase of the water of the tides, and which it can feed the aqueduct of Ravenne. Though that downstream from Silver plated, dimensions of the bed and the flows could allow navigation, however for flat bottom boats. The river, would accept certain vats (for example that in locality Sant' Alberto), but is absolutely not exploited to this end, even by the vast estuary, because far from inhabited centers or of industrial facilities. But especially the Aposa torrent historically important, is in the past named Avesa, (course of 10 km, with meadows source of Roncrio), it is truth " fleuve" city, while passing in the older part of historical center (it bathes the Due Torri, meadows of old the Via Emilia Roman - now buried -).

Risings of Reno

The risings of the river were always important; Primarily due to its affluents which descend all from the same area of the Apennin S. the most significant floods to the XX centuries are: 1934, 1937,1939,1940,1949,1949,1951,1951,1959,1966,1966,1990,1994, and 2000. To mitigate this phenomenon a little too repetitive, already in 1807 Napoleon Bonaparte authorizes the digging of a channel, the Cavo Napoleonico (or fuller of Reno ), since the curve of Reno close to Sant' Agostino in the north of Cento (area of Ferrare) until in the Po with Bondeno. these 18 km of derivation improved the situation, except in the event of simultaneous rising of the two rivers.

Internal bonds

External bonds

Photograph gallery of the valley of Reno
{it} Dates of principal floods the XX century old

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