Earth and Moon

How does a desert form?

How does a desert form?

There are atmospheric conditions and climatic regimes that naturally leave behind desert, unproductive lands, with hardly any plants in them.

Numerous actions of man seem to favor and expedite this desert-generating process so that, being aware of it, we can avoid the fatal consequences, slow down the process and even make it reversible. Let's analyze how.

According to scientific estimates, one third of the planet's surface will be deserted in the year 2,100. This may be due to climate change, which implies a radicalization in the climatic seasons. There are more and more dry seasons, with hardly any rainfall and with high temperatures, and humid, with torrential rains, hail and snowfall in levels where, once upon a time, it was unthinkable that it snowed.

The problem of desertification is a closed circle, because when the climate changes to warmer and drier conditions, part of the vegetation dies. When the plants disappear, the soil cannot release moisture into the atmosphere and therefore will not rain. In addition, as there are no roots that support the ground, the soil is dragged by the water in favor of the slope, forming cracks, known as gullies.

Because of the high temperatures and sun exposure, the little water that remains in the soil rises to the surface, evaporating and leaving the soil cracked and flaking by calls drying cracks.

Measures to prevent and correct desertification

To prevent desertification from progressing in an area, degenerating into a desert, the main thing is to get to know the potential loss of soil that could suffer and, for this, two types of methods are often used.

He direct method It is called that because it consists in the direct observation of the degree of erosion that a soil is suffering before our eyes, day by day. For this we talk about:

physical indicators: which consist of nails or rods with certain marks placed vertically on the ground in certain areas with slopes. After a time of measuring the landmarks, the amount of soil that is lost can be estimated, if they have tilted with respect to the vertical (it would report a potential danger of landslide), if cracks have appeared (warning of the formation of gullies), appearance of clear spots on the ground (accumulation of salts by evapotranspiration), etc.

biological indicators: an area is chosen in which the evolution of vegetation will be studied over time. Depending on it, different degrees of erosion will be distinguished: zero (vegetation remains dense, without showing bare roots), low (cleared vegetation, with slight exposure of roots and erosion pedestals or accumulation of sand and stones less than one centimeter high next to the roots), medium (cleared vegetation, with pedestals 1-5 cm high), tall (sparse vegetation with pedestals 5-10 cm high) and very high (formation of ravines and gullies, with hardly any vegetation).

He indirect method it consists of the so-called "universal equation of soil loss" or USLE Universal Soil Loss Equation) developed in the United States around 1930, although it did not begin to be used until 1965.

This equation has this form: A = RKLSCP where A is the loss of soil in the area considered, R measures the erodibility caused by rain, L corresponds to the length or extent of the slope, S is another parameter related to the slope, C depends on the use that has been given to the soil (used for cultivation, or for livestock, or to build a house, etc.) and P relates the loss of the soil with the mechanics that it has suffered (construction of terraces, plowing in parallel lines, plowing following the curves of the ground, etc.).

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Desertification and desertificationDeserts created by man