diving in Lake Tovel

pianta 33 27.10.2019.MP4

Video:

specimen n° 33 (silver fir) located at a depth of 36 meters. Video shot by Tiziano Camagna.


Lake Tovel is a glacial lake that was formed with the retreat of the glaciers during the last ice age. The dives revealed by drilling on the submerged trees of the relict forest (fir and beech) that the landslide which enlarged Lake Tovel (rising from 20 m to the current metres) took place around 1597 (indicated by the final age of the submerged trees). The age of the submerged trees dates back to 1089 until 1597.


The difficulties of diving in Lake Tovel

 

Diving in Lake Tovel is allowed only for scientific reasons!


the factors that characterise diving in alpine lakes such as Tovel can be summarised as follows:

The presence of a rather important layer of glacial silt on the bottom of the lake basin and the presence of suspension drastically reduce visibility. In these cases, the movements oblige the diver to use instrumental navigation with a depth gauge and compass. Important is the presence of a line (guide wire) that unites the rooted plants to allow divers to carry out research activities in safety.

 

Current technology comes in handy: dry suits, undersuits and gloves heated thanks to a battery pack, torches, and latest generation LED illuminators; furthermore, a diver propulsion vehicle (DPV) makes it possible to quickly reach the points where the research activities are carried out and to avoid excessive gas consumption. Specifically, for particularly cold water, a dry chamber system is used that is equipped with a manual locking system in the event of a malfunction (above all self-dispensing due to stiffening of the membrane due to low temperatures). Furthermore, hyper-oxygenated mixtures are used which, in addition to allowing longer bottom times and shortening the decompression stages during the ascent, favor greater cleansing of the blood and tissues from the nitrogen micro-bubbles that accumulate during the dive.

 

The aspect relating to barometric pressure becomes of fundamental importance: while at sea level, we have a pressure of 1 atm equal to 763 mm Hg (millimeters of mercury). The higher we go, the more the pressure decreases. At 3000 m, for example, we will have a pressure of 0.7 atm with 525 mm Hg.

When we go up in altitude, a part of the gases begins to be released into the environment, but another remains in supersaturation for a certain time. Our body takes about 48 hours to reach the new balance.

In fact, as we rise in altitude, our initial saturation equilibrium condition will change into a condition of oversaturation, in a certain sense diving before 48 hours have elapsed will be like carrying out a repetitive dive.

The decrease in pressure will affect the saturation and desaturation times of our tissues. This happens because the gases dissolved in our body are in a condition of balanced saturation at the altitude in which we live.

 

If, for example, we dive at sea level to – 35 m (a depth equal to that of Lake Tovel) we will have:

• Surface pressure at sea level = 1 atm

• Absolute pressure = 4.5 atm (3.5 atm of hydrostatic pressure + 1 of surface)

• Ratio between absolute pressure and surface pressure = 4.5 : 1 = 4.5 as danger factor.

 

If we dive at 3000 m a.s.l. at - 35 m we will have:

• Surface pressure at 3000 m = 0.7 atm

• Absolute pressure = 3.5 + 0.7 = 4.2 atm

• Ratio between absolute pressure and surface pressure = 4.2 : 0.7 = 6.0 as danger factor, a situation that we will find at sea but at a depth of - 50 m!

 

Conclusions:

New technologies, knowledge regarding the programming of high-altitude dives and specific training have undoubtedly allowed the recovery of very precious and important data for the purposes of research and studies of the relict forest of Tovel.