Watersheds: what are they, types and importance

To start with this interesting topic, we will first give its definition. A hydrographic basin is a depression in the ground , surrounded by higher ground, in which the water coming from precipitation or thaw converges. Thus the water that reaches the hydrographic basins flows into a sea, river, lagoon, ocean or other body of water. In short, watersheds constitute a natural water drainage system and a set of watersheds that flow into the same place is called a watershed.

Now, with respect to how watersheds are formed , they are related to the water cycle . During rainfall, rainwater can evaporate, infiltrate the ground, or circulate downhill through basins, the same happens with meltwater. When the basin depression is large enough, a permanent water current can originate, fed both by surface currents (rainfall, thaws and rivers) and by underground currents, thus forming a hydrographic basin.

Here you can learn interesting information about how rivers are formed .

We continue to talk about the characteristics of watersheds and focus on how they are structured. We can identify the following parts or elements of watersheds :

• Upper basin: it constitutes the zone of birth of the river, which moves by a great slope.
• Middle basin: it corresponds to the river valley area and there there is a balance between the solid material carried by the current and that which is deposited.
• Lower basin: it is the lower zone of the river in which the material carried along the basin is deposited, as a result of the slower current speed. In general, plains are formed in this sector.

As the hydrographic basin or river basin is in itself the base of this, we can say that these are also the main parts of the rivers and here we will talk to you in more detail about this topic.

Depending on the body of water where the waters of the basins arrive, they can be classified in different ways. Therefore, here we will differentiate the different types of river basins that exist and we will mention some examples.

Exoreic or open basins

They are those basins that drain their waters into the sea or oceans. A clear example is the Plata Basin, one of the hydrographic basins of Argentina or the Miño Basin, one of the many hydrographic basins in Spain. The two mentioned basins culminate in the Atlantic Ocean. We can also name the Escarrea River basin, a hydrographic basin of Panama that empties into the Pacific Ocean.

Endorheic or closed basins

These are basins that flow into lakes, lagoons or salt flats that do not have communication with seas or oceans. As an example we can mention the Lake Titicaca Basin, which is a hydrographic basin of Peru and Bolivia, and the Lake Valencia Basin, one of the hydrographic basins of Venezuela.

Arreicas basins

They are basins whose water evaporates or infiltrates the ground before encountering a body of water. The most frequently mentioned example of an arreica-type river basin is the Qattara Depression in the Libyan desert.

Watersheds are important both at the ecosystem level and also for the development of human activities. What is the importance of watersheds exactly? We show you some examples:

• First of all, they regulate the flow of water , therefore their presence reduces the risk of natural hazards such as floods or landslides.
• In addition, they regulate water quality and are a source of fresh water , the sustenance of all the biodiversity that inhabits planet Earth. Here you can learn about Freshwater Ecosystems .
• Thanks to the speed of the water in the basins, we can obtain hydroelectric energy for the development of our activities.
• Finally, we cannot fail to mention the scenic beauty of the river basins that are often part of our recreational activities.

If you have come this far, you will understand how fundamental river basins are for the well-being of all species. Therefore, here we will tell you how to take care of hydrographic basins .

• In principle, we must know that water is an extremely valuable natural resource that, today, faces great pollution and overexploitation. You can learn more about these problems by reading these articles on Causes and consequences of water pollution and Overexploitation of water: causes, consequences and solutions . So protecting water is crucial and if we succeed, we are also protecting watersheds.
• On the other hand, the constructions on the hydrographic basins involved in the urbanization, in works for irrigation, energy or communication routes, can affect the normal functioning of the basins. Therefore, the creation of protected areas that include these zones will undoubtedly allow their long-term protection.
• At the individual level, apart from avoiding directly contaminating the waters of the rivers and the surroundings of the basins, we can demand better management of hydrographic basins from the relevant authorities in our area, the city council, the government, etc.
• We can also join organizations and environmental associations that carry out actions to take care of the hydrographic basins in the area where we live. For example, garbage cleaning days (also called trash beauty ) are held in rivers and in the mountains or forests where they are found.

We recommend you read this other article on Why water is a renewable but limited resource , to better understand the importance of taking care of water and the places it circulates, such as these basins.