New Solutions of the Problem of Waterway Thermal RegimeRegulation in the Downstream of Hps ( Applicableto Hps Construction on the Siberian Rivers)

摘要

The publication presents means to solve thermal regime regulation in downstream of high — head and medium — head HPPs in climate zones with seasonal cycles ( the Siberia, the north regions of Canada, Alaska) .It is known that in hydro — system downstream there is forming ecologically unfavor — able regime. The typical feature of this regime is considerable difference of water temperature passed through HPP turbine from river water temperature in summer before HPP has been built. Such violation of domestic thermal regime of the river is stipulated by the fact ( accounting for reservoir drawdown in winter period) that water intake chambers of HPP turbine channels are at low height where the temperature of input water does not usually exceed 4～5 °C and is not lower than 3°C .Because of this in winter there is formed multi — kilometer water — opening in the down — stream zone of the river and in summer water in this zone is colder than in natural conditions. Such situation to some extent is typical nearly for all high — head hydro — systems operating in climate conditions with seasonal cycle. That is why the problem of downstream hydrothermic regime regulation for such hydro — systems ( the problem without comprehensive solution) was often " stumbling block" to substantiate expediency of hydro — system construction. However for today the suggested mobile intake basins ( plunge basins ) with limited threshold length located in front of HPP building as means for selective water — intake will be inefficient for operation of large HPPs with turbine flow rate of 200 ～ 250 m~3/s.We suggested another solution of the problem. Water — intake unit should be on the bank slope instead of stereotyped place. In that case restrictions in a choice of the unit length are eliminated and there appears the possibility to decrease specific water inflow up to the value when it is provided stability of " thermocline" — a comparatively thin layer within which there is observed temperature — density hop in the reservoir.