5.3 River straightening
There were four river straightening periods in the Lower Jingjiang River from 1949 to 1972 (Table 4), and these periods had a great impact on the riverbed evolution in the Jingjiang River. On the one hand, the flow velocity increased in the early stage of river straightening, which led to channel erosion, main-flow swing and bank failure. On the other hand, channel erosion lowered the river bottom elevation and weakened the diversion flow of the three spillways, which is equivalent to increasing the discharge of the Jingjiang River when the inflow is constant.
Table 4 River straightening in the Jingjiang River