کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4686529 1635549 2009 8 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Seasonal variations of sediment discharge from the Yangtze River before and after impoundment of the Three Gorges Dam
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات فرآیندهای سطح زمین
پیش نمایش صفحه اول مقاله
Seasonal variations of sediment discharge from the Yangtze River before and after impoundment of the Three Gorges Dam
چکیده انگلیسی

Over the past decades, > 50,000 dams and reforestation on the Yangtze River (Changjiang) have had little impact on water discharge but have drastically altered annual and particularly seasonal sediment discharge. Before impoundment of the Three Gorges Dam (TGD) in June 2003, annual sediment discharge had decreased by 60%, and the hysteresis of seasonal rating curves in the upper reaches at Yichang station had shifted from clockwise to counterclockwise. In addition, the river channel in middle-lower reaches had changed from depositional to erosional in 2002.During the four years (2003–2006) after TGD impoundment, ~ 60% of sediment entering the Three Gorges Reservoir was trapped, primarily during the high-discharge months (June–September). Although periodic sediment deposition continues downstream of the TGD, during most months substantial erosion has occurred, supplying ~ 70 million tons per year (Mt/y) of channel-derived sediment to the lower reaches of the river. If sand extraction (~ 40 Mt/y) is taken into consideration, the river channel loses a total of 110 Mt/y. During the extreme drought year 2006, sediment discharge in the upper reaches drastically decreased to 9 Mt (only 2% of its 1950–1960s level) because of decreased water discharge and TGD trapping. In addition, Dongting Lake in the middle reaches, for the first time, changed from trapping net sediment from the mainstem to supplying 14 Mt net sediment to the mainstem. Severe channel erosion and drastic sediment decline have put considerable pressure on the Yangtze coastal areas and East China Sea.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Geomorphology - Volume 104, Issues 3–4, 15 March 2009, Pages 276–283
نویسندگان
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