Spatial-temporal effects of temperature control device of stoplog intake for Jinping I hydropower station

This article presents an analysis of the spatial-temporal effect of multi-level stoplog gate intake adopted at Jinping I hydropower station, which is to reduce the adverse impacts on fish breeding caused by cold water discharged from the station in spring and summer. A mathematical model is applied to predict the temperature distribution in reservoir and outflow temperature process of the downstream of Jinping I station with two different types of intake—low level single intake and multi-level stoplog gate intake. For a single station, the latter shows great improvement over the former on temperature distortion (suitable for fish breeding). In order to evaluate the cumulative effect for different intake types, the analysis is extended to include the next four hydropower stations downstream. The results show that the outflow temperature of stoplog intake is more close to the nature condition comparing with the low level intake for the Jinping I hydropower station. Especially the side effect of cold water in April during temperature raising period can be well improved, but no obvious effect in winter. Jinping I hydropower station has dominated influence on temperature process at lower reach of Yalong River. Influenced by the downstream hydropower station cascade, cold temperature effect in spring and summer seems to be cumulatively enhanced, but the heating effect turns weakened during winter. The analysis suggests the improving effect of stoplog intake can maintain 80% at estuary in April, which clearly shows that stratified intake scheme used in control station can mitigate the cold temperature effect in spring and summer for the whole river basin.