Page - 236 - in Book of Full Papers - Symposium Hydro Engineering

The initial water storage time of TGR is September 1st, 10, 20 and October 1st, athe initial water level starting from the flood control limit 145m.Considering flood risk and scheduling requirements, the maximum water level at the end of September is controlled at 165m.During the water storage period, the needs of the downstream shipping, production and ecology should be taken into account, so as to minimize the impact of reservoir impoundment on the middle and lower reaches of the Yangtze River.The minimum discharge of TGR is 10000m3/s in September and 8000m3/s in October, and full storage at the end of October. Impounding from October 1st, the number of non-full storage years are 25 years in 2017 level year and 26 years in prospective level year , and the rate of full storage is 77.3% and 76.4%, respectively.Impounding from September 20, the number of non-full storage years are 12 years in 2017 level year and 18 years in prospective level year , and the rate of full storage is 89.1% and 83.6% respectively.Impounding from September 10, the number of non-full storage years are 6 years in 2017 level year and 15 years in prospective level year , and the rate of full storage is 94.5% and 86.4% respectively.Impounding from September 1st, the number of non-full storage years are 4 years in 2017 level year and 11 years in prospective level year , and the rate of full storage is 96.4% and 90.0% respectively. In 2017 level year, TGR began to impound from September 10th and reached 90% of the designed rate. In the future level year, due to the large storage capacity of new reservoirs, it was necessary to store water in advance until September 1st, so that the design storage rate of 90% could be achieved.The influence of different level year on the full storage rate of TGR is shown in table 1. Table 1 The influence of different level year on the full storage rate of TGR Date Year of non-full Full storage rate 2017 prospective 2017 prospective Oct.1st 25 26 77.3% 76.4% Sep.20 12 18 89.1% 83.6% Sep.10 6 15 94.5% 86.4% Sep.1st 4 11 96.4% 90.0% Based on the calculation and analysis, it is reasonable for TGR to start impounding on September 10 in accordance with the current joint storage of cascade reservoirs in the 2017 level year. Due to the large storage of new large reservoirs in the prospective level year, without considering raising initial water level of impounding, TGR should be further advanced to September 1 to meet the initial design full storage rate. 236