长江中游裁弯工程的效果

下荆江中洲子和上车湾裁弯工程实施已30多年.裁弯工程竣工后,对新河发展和老河淤积过程,裁弯段上游和下游河段的河道演变及水位变化等进行了长期的观测研究.观测分析结果表明:裁弯后新河按预期目标发展,老河相应淤积,老河同期淤积量大于新河冲刷量;裁弯后裁弯河段上游河道比降加大,河床冲刷,同流量的水位较裁弯前降低,其降低值自下游往上游减小,枯水期大于汛期;裁弯段以下至城陵矶河段未发生淤积,且略有冲刷,同流量的水位没有抬高,城陵矶至武汉河段在裁弯后至80年代中期曾发生淤积;裁弯后逐步实施新河及其上下游河段的护岸工程,目前下荆江河势总体稳定,裁弯工程效益得以长期发挥.

Effect of Cut-off Engineerings at Middle Reach of Yangtze River

The artificial cutoffs of Zhongzhouzi and Shangchengwan river bends of lower Jingjiang in middle Yangtze reach had been completed more than 30 years. The longterm observation results show: New river channels have developed as anticipated and old river bend channels are being silted up. The amount of sediment deposition in old channels is larger than that of erosion in new channels in the same period. The river channel slope upstream cutoff is increasing with riverbed erosion, and the water stages for the same discharge correspondingly lowered. The stretch downstream of cutoffs to Chenglingji doesn't occur sedimentation and appears slightly eroded, and there is no rise of water stages for the same discharge. Only in the stretch from Chenglingji to Wuhan,in period after cutoff to middle of 1980s there occured some sedimentation. Bank protection works are carried out successively for the new river channel and both upstream and downstream stretches. The present fluvial regime of lower Jingjiang is steady as a whole, and the artificial cutoffs are bringing forth their longterm positive effects.