Etsch-Gardasee tunnel

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Outlet of the tunnel on Lake Garda

The Adige-Gardasee-Tunnel (sometimes also Mori-Torbole-Tunnel , Italian Galleria Adige-Garda ) is an artificial drainage channel for the flood regulation of the Adige in Italy . Flood water can be channeled from the Etsch into Lake Garda through the approximately ten kilometer long tunnel in order to lower the water level of the Etsch. It serves as a flood protection on the lower reaches of the Adige and especially the city of Verona .

Course and specifics

The inlet structure

The Adige-Gardasee tunnel begins in the northeast of the municipality of Mori in the Ravazzone district. ( Map ) It runs in a strictly straight line to the west with a southerly deviation of about three degrees. It meets Lake Garda about a kilometer south of the center of Torbole on the SS 249 road in the direction of Malcesine . ( Map ) It crosses under the dry Loppio Lake , where the smallest surface layer is about 20 meters above the tunnel.

The inlet structure of the tunnel has four openings, each 9.5 m wide, which are closed with overlapping panels. The mean diameter of the tunnel is eight meters. The inlet is 106 meters higher than the outlet, which for the length of the tunnel of 9,873 m corresponds to an average gradient of 1.1%, but this is reduced to 0.87% for the course in between due to steeper slopes at the inlet and outlet . The gradient enables the water to flow independently. When the cross-section is fully utilized, the water reaches a flow speed of 11 m / s. This results in a delivery rate of around 500 m³ / s. However, only 3,700,000 m³ of added water increase the water level of Lake Garda by 1 cm. This corresponds to a full load operation of about two hours. The lowest flow velocity is 5 m / s.

history

It was the Franciscan priest and cartographer of the Republic of Venice Vincenzo Maria Coronelli who first expressed the idea of ​​using Lake Garda as a reservoir for the Adige in 1712. According to his plans, an eight kilometer long tunnel should be led from the Veronese Klause to the southern lake area. The plan was dropped again because of the small gradient.

Concrete plans finally emerged in the 1930s. After test drilling, the building permit was issued on February 3, 1939, and construction began on March 1, 1939.

During the Second World War , further construction of the tunnel came to a standstill. By then it had been driven to a length of 3.6 km, of which a little more than 2000 m on the outflow side at Torbole. Instead, in autumn 1943, preparations began on the Torbole side of the bomb-proof tunnel and some side tunnels for use by the armaments industry. In the spring of 1944, the Caproni-Werke Torbole started operations with around 1300 workers, some of whom came from the tunnel construction company Federici-Galluppi. Supplied parts for aircraft and missiles were manufactured for the German armaments industry, for example for the Me 163 , the Me 262 and the “ wonder weapons ” V1 and V2 .

Access to the maintenance tunnel

In 1954 tunnel construction was resumed. Since water ingress was feared when crossing under Lago di Loppio , it was pumped out. However, after opposing discussions, it was not replenished. In 1956, a maintenance tunnel and escape route were constructed at the level of Lake Loppio, which also served for ventilation during construction. Rain-dependent seepage water penetrating into the tunnel is still discharged with the help of a drainage tunnel under the actual main tunnel. The volume averages around 400 to 600 l / s.

On December 4, 1958, the tunnel breakthrough took place at km 2.9 from the tunnel entrance at Mori. The Etsch-Gardasee tunnel was completed on May 18, 1959, and was first used on November 17, 1960. The tunnel was extensively renovated between 2015 and 2016.

A total of 15 workers were killed during the construction work due to accidents at work, seven in the first construction phase between 1939 and 1943 and eight between 1955 and 1958. A memorial plaque is dedicated to them at the tunnel exit near Torbole.

use

The state water authority (Magistrato alle Acque) was responsible for the operation of the tunnel until 2000 . Since then, the area of ​​responsibility has been transferred to the Autonomous Province of Trento , which decides on the Trento civil defense and in coordination with the neighboring regions concerned on the opening of the bulkheads.

The use of the tunnel harbors ecological risks for Lake Garda. The sudden penetration of the significantly colder water of the Adige and the clouding of the sediments carried along lead to a deterioration in the habitat of the fish that cannot be neglected, especially in the vicinity of the discharge point. That is why the tunnel is only opened in extreme flood situations; in the 60 years since it was founded, this was only the case eleven times up to 2019, for example during the November storms in 1966 or during the autumn storm Vaia in October 2018. Apart from that, it is greatly reduced for maintenance purposes Flow open regularly for a short time.

The opening days of previous uses, the amount of water discharged, the maximum flow rate per second and the increase in the Lake Garda level caused by the discharge:

Flowing into the lake when the tunnel opened in October 2018
date total quantity Max. flow Level rise
17th November 1960 70,000,000 m³ 450 m³ / s 19.3 cm
September 2, 1965 79,000,000 m³ 440 m³ / s 21.4 cm
17th August 1966 17,000,000 m³ 280 m³ / s 4.5 cm
4th November 1966 64,000,000 m³ 492 m³ / s 17.2 cm
September 14, 1976 12,000,000 m³ 300 m³ / s 3.4 cm
17th November 1980 26,000,000 m³ 300 m³ / s 7.1 cm
July 19, 1981 7,000,000 m³ 300 m³ / s 1.9 cm
May 23, 1983 20,000,000 m³ 300 m³ / s 5.4 cm
November 17, 2000 4,700,000 m³ 100 m³ / s 1.3 cm
November 26, 2002 6,100,000 m³ 100 m³ / s 1.7 cm
October 29, 2018 17,500,000 m³ 350 m³ / s 4.7 cm

So far, the bulkheads have only been fully opened during the extreme November floods of 1966, which contributed significantly to easing the flood situation downstream. Thanks to the Adige-Gardasee tunnel, the city of Verona and the provinces of Verona and Rovigo , unlike Florence, escaped such a flood disaster in the autumn of 1966.

Web links

Commons : Etsch-Gardasee-Tunnel  - Collection of images

Individual evidence

  1. ↑ a b c Vittorio Christofori: La Galleria Adige-Garda ed il Lago di Loppio. Archived from the original on November 15, 2019 ; accessed on November 15, 2019 .
  2. ^ A b L'alluvione del 3‐4 November 1966 nelle Tre Venezie Considerazioni (malinconiche) dopo 50 anni di Luigi Da Deppo Professore Emerito - Università di Padova. In: collegioingegnerivenezia.it. Retrieved November 18, 2019 (Italian).
  3. ↑ Maria Garbari, Tullio Rigotti (ed.): Per gli 80 anni dall'inizio dei lavori della Galleria Adige-Garda. In: Gruppo Culturale Nago Torbole (ed.): La Giurisdizione di Pénede: Quaderno periodico di ricerca storica. Year XXVII - No. 53 December 2019, Arco 2019 ISSN 2284-0214 p. 10
  4. ^ Provincia Autonoma di Trento. Servizio parchi e foreste demaniali (ed.): Progetto per la tutela e la valorizzazione del biotopo di interest provinciale "Lago di Loppio" p. 28
  5. ↑ Giuliana Gelmi, Donato Riccadonna, Gloria Valenti (eds.): I ghe chiamava lingerie de galleria: Storia degli uomini che hanno costruito la Galleria Adige-Garda 1939-1959. Museo Alto Garda, Riva del Garda 2018 ISBN 978-88-6686-069-3 p. 168
  6. ↑ Giuliana Gelmi, Donato Riccadonna, Gloria Valenti (eds.): I ghe chiamava lingerie de galleria: Storia degli uomini che hanno costruito la Galleria Adige-Garda 1939-1959. Museo Alto Garda, Riva del Garda 2018 ISBN 978-88-6686-069-3 p. 175
  7. ↑ I livelli ei paleo-livelli idrometrici del Lago di Garda. About the hydrometric levels and palaeo-levels of Garda Lake. In: geoalp.eu. Retrieved November 18, 2019 (Italian).
  8. ↑ Giuliana Gelmi, Donato Riccadonna, Gloria Valenti (eds.): I ghe chiamava lingerie de galleria: Storia degli uomini che hanno costruito la Galleria Adige-Garda 1939-1959. Museo Alto Garda, Riva del Garda 2018 ISBN 978-88-6686-069-3 p. 156