Investigating the Efficiency of Pump and Water Jet Technique for Desilting Dam Reservoirs

This paper presents a novel technology for desilting dam reservoirs in a continuous and controlled manner. The proposed technology utilizes a suction system that incorporates two pumps: a dredge pump for removing and transporting sediments, and a high-pressure submersible pump for generating water jets to create turbulent flows in the bottom sediment layers. To evaluate the effectiveness of the proposed technology, local experiments were conducted in two cases: with the suction pump alone and with the addition of water jet flow. These experiments were conducted at the end of the reservoir of Zenouz Dam, which serves as a case study. The collected sediment mass was measured over time, and the resulting mass-time graphs revealed three distinct phases: ascending, descending, and constant. Based on the local conditions, soil properties and dredging system, the maximum sediment mass removal rates by the pump were 100 g/s for the case without water jet and ranged from 200 to 430 g/s for the case with water jet. Dimensional analysis was performed to determine the relationship between sediment yield and parameters such as sediment volumetric flow rate and sediment mass flow rate. The results showed that the variations of sediment discharge followed the same characteristic curves (discharge - height) of the pump. The average de-sedimentation efficiency was found to be 7-14% and 2-3% for the experimental pump modes with and without the jet flow, respectively. This indicates that the water jet flow has a significant influence on enhancing the de-sedimentation efficiency, and without it, the sediment removal would not be feasible.