Energy Dissipation Problems Downstream of Jinnah Barrage

Jinnah barrage is one of these barrages recommended by the Evaluation Consultants for rehabilitation and modernization works. Feasibility study for “Rehabilitation and Modernization of the Jinnah Barrage” noted that the hydraulic jump do not form over the glacis rather sweeps on the floor. The un-dissipated energy is causing damage to the impact blocks, the adjacent concrete floor and downstream loose stone apron. Feasibility consultants suggested curative measures, such as the construction of subsidiary weir at a distance of about 800ft downstream of the barrage and river training works upstream of the barrage. The finalization of rehabilitation works (either subsidiary weir or its alternative) is in progress and subsequently the detail design of the selected alternative will be carried out. The main focus in this study is to review previous studies/investigations, energy dissipation mechanism, river survey, sounding and probing data to establish the extent of damages and precisely the root cause for the damages.