4.2 Flow connectivity
After the impoundment of the TGD, the downstream erosion increases the
discharge capacity of the river channel. The discharge capacity of the
flood channel in the Zhicheng, Shashi and Jianli hydrological stations
increased from 48963 m3/s, 36495
m3/s and 32068 m3/s before 2003 to
53807 m3/s, 40105 m3/s and 33080
m3/s, respectively, after 2003. However, due to the
formation of the central bar at the Luoshan hydrological station, the
discharge capacity of the flood channel slightly decreased from 45500
m3/s to 43723 m3/s before and after,
respectively, the reservoir impounding. In addition, according to the
calculation method of ecological flow (Guo, 2007), the ecological flow
is approximately 15% of the annual average runoff in the middle and
lower reaches of the Yangtze River. Therefore, the ecological flows of
the Zhicheng, Shashi, Jianli and Luoshan hydrological stations are 2079
m3/s, 1855 m3/s, 1696 m3/s and 3019
m3/s, respectively.
From 1955 to 2015, the average annual runoff of the Shashi, Zhicheng,
Jianli and Luoshan hydrological stations in the Jingjiang River was 390
billion m3, 437 billion m3, 358.6
billion m3 and 630.3 billion m3,
respectively (Fig. 4). The annual runoff of the Jianli station tends to
increase, which may be caused by the decrease in the diversion
discharge. The runoff of the Luoshan hydrological station had no obvious
change in trend before 1998 but the amount decreased slightly after
1998. However, there is no obvious trend of runoff at the Zhicheng and
Shashi hydrological stations.