Shihmen Reservoir is a multi-objective reservoir, but it was original designed without any silt-sluicing facility in 1963. Through years of operation the reservoir has faced severe siltation. In order to maintain the capability and stability of water supply, some reduce deposition measures were planned by Water Resources Agency, Ministry of Economic Affairs (WRA).
Water Resources Planning Institute, Water Resources Agency, Ministry of Economic Affairs (WRPI) has done experiments as below: (1)Preliminary study for sediment sluicing and flood diversion engineering of Shihman Reservoir (2)Amuping desilting tunnel of Shihmen Reservoir. The major experimental results are summarized as the following:
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Preliminary study for sediment sluicing and flood diversion engineering of Shihman Reservoir:
The physical model study of Shihmen reservoir was conducted by using a 1/100 undistorted scale model (Figure 1). It covered 15.5 km longitudinal length of the reservoir with its upstream boundary located between reservoir cross section 30 and 31. The model needed a lab space of 120 m by 20 m.
There are a number of scenarios tested in the physical model with the flow conditions in Typhoon Aere: three sediment bypass tunnel named Case A2 (Figure 2 (a)、(b)), Case C1 (Figure 2 (c)、(d)) and Case D2(Figure 2 (e)、(f)).
Above test results, Case C1 and Case A2 were better. But its construction were costly with the tunnel lengths of 8.1 km in Case A2. Therefore, Case C1 and Case D2 have been considered as two effective strategies for sediment releasing in Shihmen reservoir.
Figure.1 Plan Layout of Shihmen Reservoir (1/100)
Figure.2 Experimental photo：(a)、(b) The model and simulation test of Typhoon Aere in Case A2；(c)、(d) The model and simulation test of Typhoon Aere in Case C1；(e)、(f) The model and simulation test of Typhoon Aere in Case D2
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Amuping desilting Tunnel of Shihmen Reservoir:
In this hydraulic model experiment project, a 1:40 scale undistorted model was used to experiment. The physical model includes intake (Figure 3 (a)、(b) ), sluicing tunnel and desilting basin 3 parts. There are several cases (including single channel with lateral flow (Figure 3 (c) ), modified triple channel (Figure 3 (d) ), different material and different deposited time…etc.) were experimented. According to the result of experiment shows that the sediment flushing rate is similar in single channel with lateral flow and modified triple channel under non-cohesive sediment of experiment. But the sediment flushing rate decreased obvious in modified triple channel when deposited time increased (water content decreased) under cohesive sediment of experiment.
Figure.3 Experimental photo：(a)、(b) Intake of Amuping Desilting Tunnel Model；(c)、(d) Test for different type of desilting basin