Environmental role of reservoirs

A water reservoir or an artificial lake is a closed space for storing water for a specific purpose. Although the term artificial lake is used trivially, it is not completely correct, because manmade reservoirs do not have the same features and functions as natural freshwater lakes.

Reservoirs are built with the purpose of water accumulation from seasonal melting of snow, for regulation of watercourses or for industrial use.

The most common method of creating a reservoir is by building a dam on a river or a stream, taking advantage of the natural features of the terrain, such as canyons and gorges, or by building embankments and barriers. Large reservoirs are usually made by damming rivers; the collected water is diverted to a valley or a small basin, which is flooded and turned into a reservoir. Artificial reservoirs are one of the most successful methods for controlling watercourses, and water and environmental management.

In North Macedonia there are more than a hundred small and medium-sized artificial reservoirs, 20 of which are located in the Bregalnica region. The reservoirs in our country were primarily built for three reasons: regulation of rivers and protection from floods, accumulation of water for irrigation of arable land, and electricity production. Some of these reservoirs have a secondary function for tourism and recreation. There are also small reservoirs in city parks or reservoirs made because of some industrial process, but these are physically small areas.

The majority of the reservoirs in the country were built in the 1955-1980 period. During this period these reservoirs also acquired a major environmental function, because they became habitats for numerous species of animals and water plants.

Artificial reservoirs and nature are constantly connected and mutually affect each other. Reservoirs can have an impact on the local climate, while nature populates them.

Reservoirs offer specific living conditions, unlike natural lakes. Their water level and temperature change significantly faster compared to natural lakes. Because the water is used, often, particularly in summer, they are at the bare ecological minimum and are prone to eutrophication and excessive algae growth.

We know today that the construction of artificial reservoirs, particularly large ones, has a direct impact on ecosystems and might threaten or destroy them. The main reasons for this are the dams that have to be built, because they change the natural course of rivers, and of course, the surfaces that need to be flooded. However, this does not mean that existing reservoirs are not ecologically important, quite the opposite; with the passage of time, water habitats become rare and reservoirs become important habitats and havens for biodiversity

There are various examples of this in the Bregalnica region. This, apart from being exceptionally rich in living organisms, the Mantovo reservoir is an important area for birds on a regional level. That is why we need to preserve these types of ecosystems, since biodiversity, and water in particular, are key in the fight against climate change.