Change in the ice and thermal regime of the Vilyui River in the lower pool of the Vilyui I?II hydrostation

Abstract

1. The investigated changes in the ice and thermal regime of the Vilyui River under conditions of operating of the Vilyui I–II hydrostation permit the conclusion that the effect of the hydrostation on various characteristics of the winter regime of the river extends over a considerable distance. 2. The increase of the winter levels is traced on a stretch more than 1000 km long, i.e., practically to the mouth. 3. A noticeable decrease of the water temperature in the summer months is observed on a stretch up to 800 km long, and an increase of temperature in the spring and fall months in a stretch 600 km long. 4. Disturbances of the ice regime of the river (a shift of the times of freezeup and breakup) do not extend farther than 400 km, in which case migration of the ice edge occurs in the 35–60-km stretch closest to the hydrostation and the formation of secondary polynyas in the ice cover is noted on riffle stretches at a distance up to 200 km. 5. Consideration of the changes in the natural ice and thermal regime of the river under the effect of activity of a hydrostation is necessary not only for evaluating the disturbances of the neutral regime in the zone of action of the given hydrostation. The data obtained can be used as analogs when planning hydroelectric stations under similar conditions.