Abstract: Stilling basin with upstream diffusion slope is widely used in middle and small-sized hydraulic engineering as it has good energy dissipation effect and adapts to the topography condition well. But there are few studies on its hydraulic jump characteristics due to the complexity of its boundary condition. In this article, the flow pattern of jump, length of jump, height of jump in different working conditions are researched through hydraulic model test. Moreover, the conjugate water depths in stilling basin of flat rectangular type, upstream sloping rectangular type and upstream diffusion sloping type in the presence of the same incoming flow are compared and analyzed. Results reveal that in the presence of the same incoming flow, still basin with upstream diffusion slope could well adapt to the downstream water level and requires smaller depth than the other two types because of its small discharge per unit width.

Key words: stilling basin, upstream diffusion slope, flat rectangular type, sloping rectangular type, hydraulic jump, conjugate water depth