Peculiarities of Water Regime Formation in Reservoirs of the Kama Cascade

Abstract

The purpose is to identify patterns of water regime formation in reservoirs of the Kama cascade. Materials and methods. The initial data were the materials of daily observations of the infl ow, discharge and water level for 2002-2021. Geographic-hydrological and statistical methods were used. Results and discussion. Long-term changes in water balance components and water level in the Kama reservoirs are determined by natural river fl ow on the one hand and cascade regulation on the other. The Kama reservoir is a regulator of the cascade. The infl ow to the Votkinskoye reservoir is fully dependent on water discharges through the Kamskaya Hydroelectric Power Plant, and the water fl ow rate is determined by the operating regulations of the Votkinskoye Hydroelectric Power Plant. At the Nizhnekamskoye reservoir, the water regime is a consequence of joint operation of the Kama’s cascade reservoirs and regulated lateral infl ow. Conclusions. The water level regime of the Kamskoye and Votkinskoye reservoirs refl ects the phases of spring rising, summer-autumn stabilisation and winter water level decrease. In the Nizhnekamskoye reservoir these phases are practically absent, and weekly fl ow regulation is clearly traced in the character of infl ow and discharge. The intra-annual distribution of water balance components in high-water years is appeared in high spring infl ows and superposition of rain fl oods waves, which cause the high-water level in the reservoir for a long time during the summer-autumn stabilization period and increased water discharge through the Normal Retaining Level throughout the entire year. The intra-annual distribution of the studied characteristics in low-water and average-water years has a similar character.