Combined removal of sediments from the Chiryurt reservoir

Conclusions

• 1. Intense passage of the sediment deposits washed from the upstream stretches of the reservoir through the cut was observed. In the cut itself or in the immediate vicinity of its outlet, 13,000 m³ of sediments was deposited, the remainder was discharged by the through-flow into the downstream pool.

• 2. The cut made was not curvilinear in plan as was intended, and therefore its expected intensive erosion by the flow did not occur. The exception was the inlet stretch of the cut, where its erosion and widening by about 10 m occurred.

• 3. An increase of the cross-sectional area of the reservoir due to the cut leads to some decrease of the level of the flushing flow in the main channel and increases its slope on the upstream stretch of the reservoir, increasing the flow velocity and effectiveness of erosion of the sediments. Furthermore, the directions of the flow velocities partially changed in the region of the cut, which intensified the effect of erosion of the sediments.

• 4. Gradual erosion of the island of sediment deposits cut off by the cut from the left-bank mass of sediments was observed during flushing and subsequent operation of the reservoir.

• 5. It is better to use diesel dredges for making cuts, which, with their self-contained power supply makes it possible to operate on any stretch of the reservoir at a sufficient distance from the bank.

• 6. The cost effectiveness of combined removal of sediments can be estimated by comparing the cost of conducting it with the cost of removing sediments by hydraulicking as the cheapest of the presently known methods. For conditions of the Chiryurt reservoir the effectiveness was 0.9 ruble/m³ of sediments being removed for the particular flushing under consideration.