Timavo System Exploration 2014: in search of the underground flow new mysteries emerge

Trieste - Timavo System Exploration 2014 (TSE 2014), the new exploration in search of the underground flow of the river Timavo, has taken place from July 13th until July 19th in Trebiciano (Trieste, Friuli Venezia Giulia, Italy).

The expedition has been undertaken by the Cave Diving Group of the French National Committee of the Fédération Française d'Études et de Sports Sous-Marins (FFESSM), on invitation and with the support of the Adriatic Society of Speleology (Trieste) and with the cooperation of several caving groups coming from Italy and Slovenia.

The river Timavo finds its sources in Croatia, in the Val Malacca, in the County Primorje Montana.

It sinks into the Škocjan Caves (Slovenia) and reappears again in the springs near the Trieste bay, in San Giovanni di Duino (Štivan). The length of the underground flow is about 41 km. Very little is known about the underground flow of the river.

Discovering the hidden flow of the river has always been a challenge for speleologists. The explorations began in the mid-nineteenth century, to overcome the problem of water supply for the city of Trieste.

However, systematic expeditions were organized only after the II World War, following the developments in the technique of underwater exploration.
 
In the meanwhile the Abyss of Trebiciano was entrusted by the municipality of Trieste to the Adriatic Society of Speleology.

In 1990/91 a large scale program of explorations was made. Groups of cave divers came from several european Countries. Among them, there were the divers of The French National Committee of the Fédération Française d'Études et de Sports Sous-Marins (FFESSM), which are by now the most renowned experts in Europe for their experience and equipment.

In early 2013 the Adriatic Society of Speleology of Trieste got in touch again with FFESSM to resume the explorations. In the last 20 years in fact, technological resources have greatly improved.

In August 2013 a group of french cave divers, lead by Marc Douchet and Michel Philips, explored two sites: Pozzo dei Colombi, a cavity which is very close to the springs of the river, and the Abyss of Trebiciano. At the bottom of the Abyss is the cave “Lindner”, where lays the mouth of a syphon, leading to an underground lake called Boegan.

While the expedition to Pozzo dei Colombi was not very satisfactory due to poor visibility, in Trebiciano Michel Philips discovered a new underwater cave.

Encouraged by the success of 2013, last week the FFESSM cave divers came again in Trebiciano and San Giovanni di Duino. This time there was also a fruitful cooperation between Adriatic Society, FFESSM and several other caving groups from Italy and Slovenia.

At least 40 people were involved: the team included ten speleologists of the Adriatic Society of Speleology - Trieste; six cave divers of the FFESSM; three speleologists from Jamarsko drustvo Sežana; one from Jamarsko društvo Temnica; one from Jamarsko društvo Danilo Remškar - Ajdovščina; one from Jamarsko društvo Gregor Žiberna - Divača; one from Jamarski odsek Slovenskega planinskega društva - Trst; two from the Speleological Group Monfalconese Friends of the Fante; five photo and video operators; other 11 speleologists of the Adriatic Society have dealt with communications and logistics.

The french divers Marc Douchet, Christian Moré, Marc Renaud and Jeremy Prieur-Drevon dived during five days of intensive research work, in very difficult conditions, including poor visibility and strong currents.

From the dives of TSE 2014 many confirmations have emerged, but also many doubts and new unanswered questions.
The researchers have understood that the Timavo is a hard nut, a very complex and challenging water system that claims perseverance and dedication.

They also realized that the conditions that may be encountered during the dives are always difficult: in 2013 there was very little visibility; this year the divers had to cope with the strong currents and visibility often minimal. There are probably some short windows of a few days during which the conditions are optimal (as far as possible...) but you have to be there in the water, just in that short time.

In Pozzo dei Colombi, in this month of July, 2014, the conditions were practically prohibitive, with strong cross-current flows at a depht of - 14 m. It was too risky to continue the explorations there.

In the Abyss of Trebiciano the mutable conditions were related to the frequent (and often intensive) rainfall in Slovenia.
It was possible, however, to fix almost 500 m. of new lanyards (a good portion of them is of stainless steel, that should hold on for a while), to go over the limit reached last year and verify the overall morphology of the site.

Knowledge of underground passages has improved a lot.
Even, new doubts have emerged. The tunnel which was found in 2013 and explored further this year did not turn out to be the passage where water comes from. The point of arrival of the main stream is still to be found.

The researchers were surprised to discover that the tunnel went south, as everyone expected a development to the east. The speleologists realized that the underwater passages go in the direction south-west, and even west. This is a real mystery.

The research group is now collecting the data and hopefully will be able to formulate some more precise hypotheses.