A lake is a large natural reservoir of generally fresh water and of considerable extension that is located within continental terrain, geographically separated from seas and oceans. A review of your classification.
According to estimates, there would be approximately 2 million lakes in the world , fluvial geographical features that, despite representing less than 0.014% of the planet’s water (since we must not forget that the seas, oceans and polar ice caps already represent the 98.2% of the total water on Earth), are one of the most interesting geological elements in the world.
Lakes are large, generally natural deposits of fresh or salt water in a depression in the ground where the water from one or several rivers, rainwater and groundwater are collected, thus forming a body of considerable extension that is found within continental terrain, thus geographically separated from seas and oceans.
The diversity of lakes on planet Earth is staggering . And it is that we can find from small deposits of fresh water to true monsters such as Lake Superior, the largest of the five Great Lakes of North America, with an area of 82,414 km², a length of 616 km, a volume of water of 12,700 km cubic and a maximum depth of 406 meters.
For this reason, in today’s article and, as always, with the help of the most prestigious scientific publications, we are going to investigate this diversity and discover the classification of the planet’s lakes according to different parameters such as their origin, formation and physicochemical properties. Let us see, then, what kinds of lakes exist.
What is a lake?
A lake is a large natural or artificial reservoir of generally fresh water and of considerable extension that is located within continental terrain , geographically separated from the seas and oceans. It is, according to another approach, a mass of still surface continental water that is deposited in depressions on the ground.
Thus, lakes are bodies of fresh or salt water that are surrounded by land and are larger than a pond. Generally located in valleys or mountainous regions, lakes are water reservoirs where there is little or no movement of these masses of water despite being fed by rivers or streams. And unlike these, when there is movement, the water does not flow in any particular direction.
These are fluvial accidents that, as we say, house approximately 0.014% of the planet’s water , collecting rainwater, groundwater or one or more rivers. These lakes are formed in topographic depressions that are created and developed by different geological processes such as the action of glaciers, tectonic movements, volcanism and even the impact of meteorites, while they can be artificial through the construction of a dam.
And it is precisely based on what process has caused a sufficient depression in the ground so that the water begins to deposit in it, forming the lake itself that we can develop a classification of these bodies of water. And then we are going to investigate this classification.
What kinds of lakes are there?
As we say, we can differentiate different kinds of lakes depending on the geological process that has created the topographic depression necessary for the development of the water reservoir, but this is not the only parameter that can be considered. The physicochemical properties, the formation, the geological characteristics… And through this analysis we have managed to collect the following classification of the lakes. Let’s see, then, what types of lake exist.
Glacial lakes are the most common and are those whose origin is due to the erosion caused in the rock by the existence of a glacier , that is, a large mass of ice that, when it disappears, leaves a depression in the ground that it will be occupied by a body of water that will form the lake. Being able to become ice masses of up to 5 km, as they advanced and retreated, the ice, which was sharp due to its load of crystals, eroded the rock.
Tectonic lakes are those whose origin is due to depressions formed in the crust as a result of the movements of tectonic plates. Thus, when, due to tectonic movements, the earth’s crust sinks, said sinking causes a topographical depression that will be filled with water to form the lake itself. In this sense, the folding of the earth’s crust creates depressions that give rise to the origin of the lake.
Karstic or karstic lakes are those whose origin is due to depressions formed in limestone terrain and soils by said karstic phenomena, that is, by an erosion of calcareous soils by the action of acidic substances that chemically erode the soil and produce topographical depressions or underground seepage.
Thus, they can form both surface lakes that develop from a surface dissolution of limestone rocks or underground lakes that originate from the filtration of water that comes from a spring or an aquifer.
Volcanic lakes are those that developed in the crater of a volcano that was once active. Thus, the depression is the crater or caldera (in which case they are especially large) of the volcano, since its eruptions caused a subsidence of the crust that led to the formation of a lake. Its waters are greatly influenced by the chemical and thermal characteristics of the dormant or extinct volcano.
Dammed lakes are those that are formed as a result of a “plugging” of the flow of water from a freshwater system that causes the water to accumulate in a depression in the land. They are generally artificial, where this is achieved through the construction of a dam, in which case we speak of a reservoir that seeks to use hydraulic energy, prevent river floods or achieve an agricultural reservoir.
Even so, there are also natural dams, where the “dam” is formed by non-artificial processes, without human intervention, such as landslides, collapsing slopes, formation of ice sheets and even, on a small scale, dams built by beavers.
Lakes due to fluvial erosion
Lakes due to fluvial erosion are those that are formed as a consequence of the erosion caused by a river, since the force of the current causes, generally in the plains, the formation of meanders, regions that adopt a pronounced curve and that can end up forming a deposit in the shape of a horseshoe that is now considered a lake.
Endorheic lakes are those that form on depressions in the earth’s surface that have no outlet to the sea, thus being small hydrographic basins. The aridity of an area reduces river erosion, so the basin remains closed and without drainage to the sea or ocean . At the same time, this aridity also results in evaporation being greater than the water supply, which causes them to be lakes that retain many salts.
Alluvial lakes are those that are formed as a result of an obstruction of the natural outflow of water due to alluvium, that is, sediments dragged by a water current that, at one point, can obstruct its flow.
Pelagic lakes are those that, in their day, were seas. But due to different processes, they dried up and only one area was covered with water, something that led to it being surrounded by land and, therefore, being considered a lake. Thus, they are vestiges of ancient seas and, therefore, have the characteristic of being highly salty .
Crater lakes are those in which the depression of the ground has its origin in the impact, in ancient times, of a meteorite. This event caused the formation of a crater that, over time, led to the formation of a lake.
Natural lakes are all those that, being of any type that we have seen in this list, were formed without the intervention of the human hand . Thus, they originated from natural processes such as volcanism, tectonic movements, fluvial or glacial erosion and even, as we have just seen, meteorite impacts.
Artificial lakes are all those that, being also known as reservoirs, were not formed by natural processes. They are lakes whose origin is due to human intervention and the construction of a dam in order to promote the accumulation of water for human benefit, be it hydraulic energy, the prevention of rises in river levels or water reservoirs for agricultural purposes.
Freshwater lakes are those that have a low concentration of salts and dissolved solids . They represent 0.007% of the total water on the planet and are the ones that usually come to mind when we think of lakes, since we associate salt water more with seas and oceans.
Saltwater lakes are those that have a high concentration of salts and dissolved solids. They represent 0.006% of the total water on the planet and, as a curiosity, the largest lake in the world, the Caspian Sea (with an area of 371,000 km²) is a saltwater lake. As we have seen, they are generally formed through processes where evaporation is greater than the supply of water, thus stimulating an increasingly higher concentration of salts in the water.