tekojärvet

Tekojärvet are artificial lakes or reservoirs created by human activity, typically by constructing dams on rivers or excavating basins to form a lake. They are built to store water, generate electricity, control floods, or provide recreation, and they differ from natural lakes in their origin and often in their hydrological and ecological characteristics.

Formation and typology: The most common type is a reservoir created behind a dam, where river flow is impounded to create a stable storage volume. Less common are off-stream artificial lakes formed by diverting water to a basin, or by excavating and allowing the area to fill with water from precipitation or groundwater. In some regions, multiple tekojärvet form a network to capture runoff and manage water resources.

Uses and functions: Tekojärvet serve municipal and industrial water supply, irrigation, hydroelectric power generation, flood control, and recreational activities such as fishing, boating, and tourism. They can provide new wildlife habitats, but may also disrupt existing ecosystems and migration routes.

Environmental and social aspects: The creation and operation of tekojärvet can cause habitat loss, alteration of sediment transport, changes in water temperature and chemistry, and barriers to aquatic movement. Sedimentation can reduce storage capacity over time. Effective planning, environmental impact assessments, and ongoing monitoring are important to mitigate negative effects and ensure dam safety.

Global context: Artificial reservoirs are common worldwide, reflecting the need for reliable water supplies and energy, with varying ecological and social trade-offs. In Finland, tekojärvet support electricity generation and regional development while presenting management challenges.