Author(s): Lijin Liu; Chao Sun; Youcai Tuo; Yun Deng
Linked Author(s): Yun DENG
Keywords: Reservoir-tail fluctuating backwater zone; Ice-jam-induced backwater; Ice-jam head; Water-level response; Ice-flood regulation
Abstract: The fluctuating backwater zone at the tail of cold-region reservoirs is jointly controlled by inflow processes and reservoir water-level regulation, making it prone to ice-jam-induced backwater during the ice season. Based on multi-year ice-regime and hydrological observations from Wanjiazhai Reservoir, this study investigates the water-level response and controlling factors of ice-jam-induced backwater in the reservoir-tail zone. The results show that the correlations between water levels at Lamawan and Shuinichang and Toudaoguai discharge decreased from 0.79 and 0.86 in the open-water period to 0.02 and 0.30 in the ice-running period, indicating a markedly enhanced influence of ice-jam-induced backwater. Water depth at the ice-jam head shows a clear relationship with discharge, reflecting the hydraulic conditions for initial ice accumulation. Wavelet coherence analysis indicates that, as the ice-jam tail develops upstream, the phase relationship between water levels at Shuinichang and Chahekou shifts from in-phase to anti-phase and then to alternating positive and negative coherence. Principal component analysis shows that thermal forcing, reservoir inflow, reservoir water level, and channel topography jointly control the ice-jam-induced backwater process. These findings provide support for ice-jam risk identification and ice-season reservoir operation.
Year: 2026