Temperature and ice regimes of waterbodies under impacts of global warming and a hydropower plant

Based on the results of regular monitoring and remote sensing data the patterns of water temperature and ice regime of the Dnipro River within Kyiv, as affected by global warming and a hydropower plant, were identified. The characteristic features of this stretch of the river are increasing water temperature, and the decreasing thickness and duration of ice cover. The largest water temperature increase is in summer, with a somewhat smaller increase in autumn. The increase of water temperature in spring is much less than the increase in air temperature. In summer, the gradient of water temperature increase is a little bit less than that of air temperature. In autumn, the gradient of water temperature increase is larger than the gradient of air temperature increase. From April to August the lowest water temperature is usually observed near the Kyivska hydropower plant (HPP), which is located upstream. During this period the water temperature downstream from HPP increases. The uneven daily operation of HPP causes the alternation of areas with different temperature along the Dnipro River. In the cold season the water temperature in the Dnipro River is usually higher than in other nearby urban water bodies. Freezing of the water area usually starts from the small and shallow lakes and ponds. The main branch of the Dnipro River freezes last. On the whole, the sequence of ice melting on the waterbodies is the reverse of the freezing process. The longest ice cover duration in spring is observed in the bays with small water exchange, mainly located at a large distance from Kyivska HPP.