Acta Geographica Sinica ›› 2014, Vol. 69 ›› Issue (3): 409-421.doi: 10.11821/dlxb201403012

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Silting/scouring process responses of Dongting Lake basin to the operations of TGR and thresholds of water-sediment regulation

ZHOU Yongqiang1,2,3, LI Jingbao1, ZHANG Yunlin2, ZHANG Xinping1, LI Xichun4   

  1. 1. College of Resources and Environmental Sciences, Hunan Normal University, Changsha 410081, China;
    2. State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, CAS, Nanjing 210008, China;
    3. University of Chinese Academy of Sciences, Beijing 100049, China;
    4. Hunan Hydro & Power Design Institute, Changsha 410007, China
  • Received:2013-09-09 Revised:2013-12-04 Online:2014-03-20 Published:2014-03-20
  • Supported by:
    National NaturalScience Foundation of China,No.41071067;Construction Program of the Key Discipline (Geography) inHunan Province

Abstract: Based on measured runoff and sediment discharge rate of major control stations in the Dongting Lake basin and the Jingjiang River section, Yangtze River, from 1951 to 2011, this paper analyzes silting/scouring process responses of the Dongting Lake basin to different impoundment phases and different dispatching modes of the Three Gorges Reservoir (TGR). Results are shown as follows: (1) Significant correlations were found between flow rate of the Zhicheng Station and flow rate of the Three (Four) Outlets of the Southern Jingjiang Rivers (r2=0.859, p<0.0001), flow rate and sediment deliver rate of the Three (Four) Outlets (r2=0.895, p<0.0001), indicating that flow rate and sediment deliver rate of the Three (Four) Outlets were strongly influenced by upstream Yangtze River flow rate. (2) Compared with period before operation of the TGR (1999-2002), sediment silting/scouring amount of the Dongting Lake basin during the TGR impoundment phases I, II and the TGR in comprehensive operation phase (2008.10-2011.12) dropped from +4796.4×104 t to +684.1×104 t, +449.8×104 t, -559.6×104 t, and sediment silting/scouring rate dropped from +70.25% to + 31.13%, +23.56%, -42.64% successively. The results present notably positive effects due to operation of the TGR. (3) During pre-discharge dispatch and water-storage dispatch period, the lake basin changed from silting to scouring mode. For flood-storage dispatch and water-supplement dispatch period, the Dongting Lake basin was mainly controlled by silting and scouring processes, respectively. (4) The calculated optimum thresholds of annual mean flow rate, sediment transport rate and sediment concentration of the Three Outlets were 970.81 m3/s, 466.82 kg/s and 0.481 kg/m3, respectively, while the Dongting Lake basin were under the state of neither silting nor scouring. The thresholds could provide practical references for operation regulation of the TGR.

Key words: Three Gorges Reservoir, The three outlets of southern Jingjiang river, sediment discharge, Dongting Lake basin, runoff