Management of the density jumps in lakes and reservoirs plays an important role in the water quality improvement and in the sediment deposition and erosion management. The density jump was studied experimentally by considering the bed roughness. Experiments were performed in a rectangular laboratory flume having a gravel bed. Using the collected data, a simple relationship was obtained for estimating the conjugate depth ratio in relatively weak jumps. The conjugate depth ratio is independent of the entrainment ratio, and depends only in this relation on the upstream densimetric Froude number and the relative roughness. For smooth beds, the spatial development of the density current was also analyzed in both supercritical and subcritical flow regimes. As the distance from the end of the jump increased, the maximum velocity drifted towards the bed. Finally, at a distance approximately fold h2 from the end of the jump, the non-dimensional vertical distribution of mean velocity had a shape similar to that of the supercritical section
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