Sediment budget of the Yangtze River

Abstract

The sediment budget is a method to study the distribution of sediment in different parts of a river basin. This paper studies the sediment budget of the Yangtze River by analyzing the data on soil erosion, size distributions of sediment deposits, sediment load, and fluvial process. A method to determine the sediment budget for the Yangtze River is proposed in which the total soil erosion from the upstream reaches and tributaries is divided into two parts: sediment load transported to the Yichang station and sediment storage in the tributaries and gullies. Furthermore, the sediment load is divided into three parts: bed material load deposited in the middle and lower reaches for the fluvial process, wash load transported to the estuary, and sediment deposition in Tongting Lake. The sediment transported into the estuary is further divided into two parts: very fine sediment drifting to the ocean and sediment deposition in the estuary for land creation. There is a large sediment demand for (1) the fluvial process to reach the minimum stream power in the middle and lower reaches; (2) sediment mining for building material; and (3) land creation in the estuary. The riverbed profile in the middle and lower reaches is developing toward the equilibrium profile defined by the minimum stream power, but the impoundment of the Three Gorges Reservoir interrupts and modifies this fluvial process. The annual sediment load in the Yangtze River has reduced due to various human activities by about 100 × 106 t in the past 15 years. Thus there is a sediment shortage for land creation in the river mouth.

Seasonal dynamics of suspended solids in a giant subtropical reservoir (China) in relation to internal processes and hydrological features

“…Consequently, the inflow discharges of the TGR is mostly concentrated from June to September (the flood season), accounting for 61% of the annual total (Huang et al, 2006). Upon its planned completion in 2009, the TGR will be one of the largest man-made lakes in the world, with a capacity of 3.93 Â 10 10 m 3 , a water level of 175 m and a surface area of 1080 km 2 (Wang et al, 1997;Huang et al, 2006). In addition, forty reservoir-bays (watershed area of individual bay >100 km 2 ) will eventually be formed by the flooding of the reservoir, and water area of these bays will account for 1/3 of the total water area of the TGR (Cai and Hu, 2006;Huang et al, 2006).…”

Patterns of asynchrony for phytoplankton fluctuations from reservoir mainstream to a tributary bay in a giant dendritic reservoir (Three Gorges Reservoir, China)

“…The Yangtze River is the third largest river in the world with a length of over 6,300 km, a watershed area of over 1.8 9 10 6 km 2 and an annual water discharge of 9.8 9 10 11 m 3 (Wang et al 1997). TGR was built on the upstream mainstream of the Yangtze River to prevent frequent summer floods driven by the summer monsoon (Xu et al 2010b).…”

How polluted is the Yangtze river? Water quality downstream from the Three Gorges Dam

“…The particulate load at Datong has decreased by approximately two thirds of its 1950-1986 loads only two years after the first cofferdam at the TGD was closed. Sediment shortage for land creation in the river mouth and, in fact, local and regional erosion of the Changjiang delta Yang et al, 2006a;Zhang et al, 2006;Wang et al, 2007) has resulted from the reduced particulate load and drawn attention to the impacts of the TGD on sediment transport.…”