Djamaa, WGhomri, AKhechana, S2023-05-292023-05-292021-05-01W . Djamaa , A . Ghomri S. Khechana ,STUDY OF THE EXPERIMENTAL APPROACH OF THE RELATIVE THRESHOLD OF THE HYDRAULIC JUMP EVOLVING IN A RECTANGULAR CHANNEL OF COMPOSED SECTION WITH ROUGH MINOR BED .Journal of Fundamental and Applied Sciences.VOL13 N02.01/05/2021.university of el oued [visited in ../../….]. available from [copy the link here]1112-9867http://dspace.univ-eloued.dz/handle/123456789/24919The aim of this experimental study is to analyze the ratio of the relative t hreshold of the hydraulic jump evolving in a rectangular channel composed with a rough minor bed. functional relations, in dimensionless terms, as a function of the Fr oude number and of the roughness were obtained. Indeed, for a fixed initial height h 1 , th e increase in the incident Froude number causes both the displacement of the step downstream. therefore, it corresponds to a length Lj of the step and Lr of the roll, as well as a height h 2 downstream of the step and a height S of the threshold.en: roughness; compound channel; relative threshold hydraulic jump; rough minor bed, thin wall thresholdArticle