Thermal regime of the Dnipro Reservoirs

Abstract

Based on the results of regular monitoring and remote sensing data the patterns of water temperature of the reservoirs cascade on the Dnipro River were identified. A characteristic feature of the thermal regime of the Dnipro Cascade has been the water temperature increase over the past decades. In the period 1977–2020 the water temperature in summer increased by 0.74 °C decade–1, and during May–October by 0.65 °C decade–1. An important factor influencing the thermal regime of the reservoirs is the influence of those ones, located upstream. Water from them is discharged from the lower layer, where the processes of heating and cooling are very slow. This has a significant influence on the water temperature of downstream reservoirs, especially on their upper part. The water temperature in this part during spring and summer seasons is lower compared to natural conditions. In autumn it is higher. The temperature of water also depends on the latitude: it rises in the reservoirs located both downstream and to the south. Another important factor influencing the water temperature is the wind, which can change the temperature in the surface layer by 5–6 °С. Water temperature also depends on the intensity of algae bloom – it is higher in the spots of a large bloom.