Page - 338 - in Book of Full Papers - Symposium Hydro Engineering

Capacity (10,000 m3) Sediment- Caused Effective Storage Capacity Loss (10,000 m3) - between the Two Measurements 1165 742 807 260 1615 -371 Sediment- Caused Effective Storage Capacity Loss (%) 1.53 7.42 10.56 11.57 17.86 16.41 According to Fig.3, the variation tendency for storage capacity of the Manwan Reservoir is: the storage capacity below NWL, dead storage capacity and effective storage capacity is reduced year by year, the loss ranges for the storage capacity below NWL and dead storage capacity are quite large and basically synchronized, and the loss range for the effective storage is relatively small. Since the Xiaowan HPP was put into operation in 2009, the sedimentation in the Manwan Reservoir area is significantly mitigated. According to Table 1, since the power plant is put into operation until 2014, the total sedimentation volume below the normal water level - 994m is 554.99 million m3, the residual storage capacity below NWL of the reservoir is 365.01 million m3 and the loss rate for the storage capacity below NWL is about 60.33%; the sedimentation volume below the dead water level - 982m is 512.81 million m3, the residual dead storage capacity is 150.19 million m3, and the loss rate for the dead storage capacity is 77.35%; and the sedimentation volume for the effective storage capacity is 42.18 million m3, the residual effective storage capacity is 214.82 million m3, and the loss rate for the effective storage capacity is about 16.41%. See Table 2 for the comparison of the measured reservoir sedimentation volume over the years and the predicted sedimentation volume in the initially-set stage. 338