Page - 339 - in Book of Full Papers - Symposium Hydro Engineering

Table 2 Characteristic storage capacity of the Manwan reservoir and sediment-caused storage capacity loss Sedimentation Volume in 5 Years 1998 Sedimentation Volume in 10 Years 2003 Sedimentation Volume in 15 Years 2008 Sedimentation Volume in 20 Years 2013 Predicated Data 1.54 2.99 4.38 5.64 Measured Data 2.43 4.29 5.48 5.55 Difference 0.89 1.30 1.10 -0.09 From the view of the total sedimentation volume, the actual sedimentation of the Manwan Reservoir in the first 15 years of operation is more serious than the result of the original design forecast. This is mainly due to the deviation in the forecast which is based upon the historical hydrological and sediment data and the specified operation and dispatching modes. From the view of the actual sediment volume, affected by human activities, the sediment volume shows a significant increase trend. From 1994 to 2008, the average annual sand volume is 60.49 million tons, but the calculated design value in the preliminary design is only 44 million tons, with an increase of about 50%; Acccording to the operating water level of the Manwan HPP recorded from 1994 to 2009, the average operating water level of the Manwan HPP since its operation during the flood season from June to September is 987.44m, which is 2.44 m higher than the results of the preliminary design. 4. SEDIMENTATION CALCULATION The sedimentation of the main stream of the reservoir is calculated by the constant flow unbalanced sediment transport method through the program SUSBED_2 provided by Wuhan University of Hydraulic and Electrical Engineering. The WUHEE Zhang Ruijin Formula is adopted as the sediment carrying capacity formula of suspended load. 4.1. CALIBRATION OF SEDIMENTATION PARAMETERS Before the sedimentation calculation of each scheme, the calibration of sedimentation parameters is carried out firstly. The calculation is carried out based on the terrain data measured in 1996 with year 2000 as the end. The 339