长江中下游分汊河段的整治

 长江中下游宜昌至徐六泾段全长1 710 km，共有分汊河段55段，可分为顺直形、微弯形和鹅头形3种汊道。主汊和支汊兴衰交替是分汊河段河道演变的共同特点，大多数汊道主支汊交替周期长，是一种相对稳定的河床形态。在长期的演变过程中，分汊河道的河床总体上处于相对平衡状态，具有与其上下游单一河段相当的泄洪能力。长江中下游分汊河段的综合整治应依据“稳定分汊河势、适度减少支汊、合理利用洲滩”的原则，结合各河段情况制定整治方案；武汉河段的整治宜根据近期河道演变和环境保护要求，采用保持天兴洲汊道为双汊河段的基本方案。

Bifurcated Channel Stretches Regulation in Middle and Lower Yangtze River

There are 55 bifurcated channel stretches in the 1710km Middle and Lower Yangtze River from Yichang to Xuliujing. They are classified into relatively straight, slightly curved, and goose-head formed bifurcated channels. They have the common characteristics of fluvial evolution with alternatively shifting of their main and secondary channels. Most of them with long period of lying such main-secondary channel alternative shift are of relatively stable fluvial pattern. In the long process of evolution the bifurcated channel stretch as a whole in a state of relative equilibrium possesses the same discharging capacity like upstream or downstream single channel river stretches. The regulation work has to comply with the general principle:"to stabilize bifurcated river regime, to decrease the number of channels, and to rationally utilize central bar and floodplain", and the exact details of regulation work have to be designed by integrating with the specific river stretch conditions. For the Wuhan river stretch, in accordance with the trend of recent fluvial evolution the adopted alternative of regulation should maintain the double channels on both sides of the islet Tianxingzhou to meet the requirement of the environment protection.