Author(s): Wang Zhiqian
Linked Author(s):
Keywords: Bore analysis; Shallow water bore; Bore speed calculation
Abstract: Through a case study, the inaccuracy of two famous formulas in computing the propagation speed of bores on floodplains was presented firstly. To theoretically search out the reason causing the inaccuracy, basic characteristics of bores were analyzed according to the theories of hydraulic jumps. The usually used two formulas were derived in detail, based on the conservation laws of mass and momentum. It was then concluded that the riverbed friction force must be considered when the concerned bores propagate on floodplains. However, this component was neglected in momentum equation as an important assumption. To avoid the same error cause, a new formula and its simplified expression were derived basing on the conservation laws of mass and energy. The calculated results from the simplified formula agreed well with the measured data. It indicates that the simplified formula is more reliable to compute the propagation speed of bores in very shallow water regions, such as on the floodplain of the northern branch at the Yangtze River estuary.
Year: 2001