Author(s): Janek Laanearu
Linked Author(s): Janek Laanearu
Keywords: River; Weir flow; Specific energy; Momentum equation; Froude number
Abstract: The hydraulic analysis of low-head dam, where the shape of riverbed has been changed due to river-basin restoration works is considered. A hydraulic analysis is based on the solution of specific energy function and momentum equation of the non-rectangular channels. The quadratic-type channel hydraulic framework (Laanearu et al, 2011) is adopted for single-layer flow to determine the energy losses due to the formation of hydraulic jump, where the free-surface flow is jumping between super- and sub-critical flow conditions. The energy-loss calculus is introduced within the open-channel hydraulic framework, allowing using geometrically non-isolated river sections for the sequent heights. Explicitly determined annual discharge for a low-land river, which is located in the northern Estonia, is used to represent local flooding conditions. A historical flow rate Q = 155 m³/s, representing the year 1931 peak discharge in the river, is used to estimate the hydraulic quantities of the pre- and post-rebuilding hydraulic structure. The rapidly varying flow processes at weir is explained by predicting the energy losses in channel.
Year: 2025