Water within the glacier

The study of glacial cave systems is very important even from a hydro-geological point of view, because it allows us to understand how the water contained in a glacier works and behaves when it is part of a glacial aquifer. The behaviour of glacial aquifers is very similar to that of karstic aquifers and are therefore studied with the same methods. First and foremost it is necessary to cover the greatest number of accessible caves, plotting a topographical survey, so as to understand how the network of galleries stretches and in which direction waters flow. For those areas that cannot be explored by man (because they are flooded or too narrow for a human to enter inside) detailed studies are carried out on the flow of the glacier recharge system, which is the source of the glacial cave systems. In particular, it is important to observe the balance between output and input flow (in this case melt water or rainfall) and how the “springs” respond to external supply. To help out in this kind of a survey, water-tracing techniques are used. A given quantity of tracing substances (generally fluorescent dyes) is introduced into the caves through their sinkholes, and how these are returned at the springs is observed. By analyzing the time taken by the tracer to flow out and the dilution it has undergone, it is possible to understand the stretching and diameter of glacial galleries, to establish if water runs along narrow joints or large galleries, to estimate the volume of water stored within the glacier and to establish for how long waters remain within the glacier. In other words, it is possible to estimate the behaviour of the aquifer and the volume of its water reservoirs. This is very important, because in many parts of the world glaciers supply an abundant source of water, for both agricultural, as in many arid regions (e.g. the Karakorum) and hydroelectric uses, as in a great number of Alpine glaciers. To be able to understand how much water is stored and in what way it flows out of the glacier is of fundamental importance  to be able to design water-tapping systems and to prevent possible risks. The presence of great quantities of water stored in a medium that moves and gets deformed continually, in fact,  can be a great danger:  the collapsing of  the walls supporting these lakes within the glaciers can lead to sudden outburst of great quantities of water, provoking the so-called glacial outbursts, one of the most destructive and impressive phenomena that glaciers can be subjected to.

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