Dams and geology: the urgency of prevention

Texts by Daniele Alami Artworks by Denise D'Orlando

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Dighe e geologia: l’urgenza della prevenzione

Dighe e geologia: l’urgenza della prevenzione

Risk and hazard  are often confused.

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Dighe e geologia: l’urgenza della prevenzione

Dighe e geologia: l’urgenza della prevenzione

Hazard represents the probability that an event happens, while risk takes into account the damage that a natural event may cause to human lives and activities in a given place affected by the event itself.

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Risk depends both on the probability that an event happens in a given place, and on the vulnerability of the place itself to the type of natural event that threatens it.

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Risk, vulnerability, and hazard probability are therefore intrinsically linked. In the following five examples we will see how well or badly  these concepts have been interpreted in regulating the construction of dams, a geo-engineering expression of fundamental importance in our country.

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CURON DAM (Lago Resia, TN)

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Diga del Curon (Lago Resia, TN)

Diga del Curon (Lago Resia, TN)

Not all floods have to be disastrous.  In the case of the village of Curon Venosta, in Trentino Alto Adige, the flooding of the village was planned in order to build the dam and  merge three lakes. The goal was to improve the energy supply from the valley.

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The village of Curon  was safely moved upstream, and the area was allowed to flood.  Trentino is an example of a highly seismic territory. For this reason its dams are constantly monitored.

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MOLARE DAM

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(Lago di Ortiglieto, AL)

Diga di molare

Diga di molare

In 1935, less than 15 years after it was put into operation, an exceptional flood caused the overflow of this isolated dam. The consequences for the surrounding villages were disastrous: a twenty meter high mud wave killed 111 people and destroyed most of the bridges and houses in the surrounding areas.

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The consequent process established that the rocky terrain characterized by finely foliated material (which when wet resembles soap) was not suitable for the construction of a reservoir.

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MONTEDOGLIO DAM (AR)

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Diga di Montedoglio

Diga di Montedoglio

In 2010 one side of this dam collapsed into the Montedoglio reservoir, the largest artificial lake in Tuscany.  In 2020, the managers of the dam were investigated for illegal waste disposal during the rebuilding of the dam.

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The mismanagement of the excavations, the burial and the summary maintenance works that do not take into account the geological and environmental characteristics put at risk not only the dam but jeopardised the entire population living down-stream of the dam.

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CAMPOTOSTO DAM (AQ)

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Diga di Campotosto

Diga di Campotosto

This Abruzzo dam was directly affected by the Amatrice earthquake on August 24th 2016.  It is currently under the magnifying glass of the Great Risks Commission.

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Prof. Alberto Pizzi, professor of geology at the University of Chieti and Pescara, declared that "Another major earthquake in the most critical area of the dam could indeed constitute a disastrous scenario."

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POZZILLO DAM (CT)

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Diga di Pozzillo

Diga di Pozzillo

The dam was built to create one of the largest artificial lakes in Europe (141 million f liters) largely to irrigate crops.  However, it requires constant maintenance due to the high risk of flooding.

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Dams are found everywhere in Italy,  from the mountains of  the cold north to deep warm south.  The problems are different from dam to dam (problems of seismicity, obsolescence or illegality) but the disastrous effects (breach of banks, landslides, floods) are the effect of bad design that did not take into account the geology and morphology of the valley.

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The importance of geology, knowledge of the territory and above all the interaction between the various scientific and institutional representatives must always be placed in the foreground.

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This is the only way to achieve higher and higher engineering and management goals, and at the same time protect people's quality of life and reduce the risk of death.

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Dighe e geologia: l’urgenza della prevenzione

Dighe e geologia: l’urgenza della prevenzione