Today I will share my first post - perhaps - of a more or less long series. #WaterLovers, I'd like to call it.
Yesterday I was biking slowly towards Forno, along the Frigido Valley. The surrounding mountains were full of improvised streams of water that form regularly when it rains ... a moment, but yesterday it didn't rain ... so where did the water come from?
We follow a logical thread: when it rains, the water rushes to the earth, crosses the rivers and ends in the sea. The rivers are really swollen, streams form on the mountains and so on. Then it stops raining ... but the water continues to be there and to descend from the mountains much more abundant than usual. The hours go by. Water continues to be present in quantity. More hours pass and the water shows no sign of diminishing. Yet he had stopped poor ... question:
Where does the additional water we see after it stopped raining come from? Let's start from the beginning.
Under the surface layer of the earth, there are real reservoirs of water, the so-called aquifers. After noting the amount of water yesterday I did a quick search on the aquifers and found that they can be of 2 types: the aquifers and the artesian aquifers. The firsts are the simplest, they are formed through the flowing water and sometimes settles between the porosities of the rocks. Yes, because some types of rocks are porous and are called reservoir rocks or aquifers rock because the water is deposited between their interstices. The water tables are separated from the outside only by a layer of soil and aquifers. The artesian aquifers, on the other hand, are strata that have a layer of impermeable soil above them.
The simplest scheme that came to my mind is the following and it is partly what happens.
The aquifer normally has water inside it and we can see the highest point that the water reaches as the normal level. When it rains and the water permeates, the level begins to rise and the aquifer fills up more and more. But the aquifers are not found only in the plains, they extend throughout the subsoil; within the mountains made up of permeable types of rock, such as limestone or dolomies, there are long stretches between rock and rock that are permeable to water. These stretches open to the outside but are normally never used because the water level does not reach the altitudes where they are present.
When it rains, the water level in the aquifer begins to rise and we can schematize what happens simply by thinking that the water level rises beyond the points where these outlet channels are located. The water in the aquifer thus finds an exit point from the subsoil and what are 2 types of springs are formed: the emergency water source and the overflow water source. The overflow water sources are those springs that do not exist until the water level in the aquifer rises above the normal limit; the emergency ones are formed when the thrust of the water in the fault causes the above ground to be cut.
I tried to schematize everything with the help of the last 3 images.
I spent the rest of my trip making a census - of course, I jokingly say - of the various streams along the mountain that flow into the main bed, that of the Frigido River. Some are normally present courses, but now much more impressive. My area is full of these streams, however small they are. The conformation of the rock in these parts is that of porous rocks that we have previously described, therefore other streams of water have formed along the mountain and I can assure you that they are very numerous. These are the streams that are never seen in moments of dryness and that we can catalog among the streams flowing from overflow watercourse and in some cases emergency watercourse, according to the mechanism seen above.
My short afternoon ends here, but I plan on releasing a few new episodes later. What I have explained is simply a very banal method to give a face to what happens, all in a schematic way. I will explain another phenomenon involved in the leakage of water from the aquifers in the next episode. I invite you not to take what I have said as the scientific idea of what is happening: it is only a reflection of short research and personal answers to simple curiosities.
I also wrote this post with the intention of associating science and photography. Not sensational photographs except for a few exceptions, but still useful for documenting my trip.
ATTENTION: the photographs contained herein were taken and post-produced entirely by me and therefore covered by copyright.