一、前言长江出三峡,即流入中游平原区。在枝江以下,一部份沿松滋、太平、藕池、调弦四口分流入洞庭湖,一部份顺荆江下泄,在岳阳城陵矶附近与四口及湘、资、沅、沣四水经洞庭湖调蓄后的出流汇合。这一段河道的比降很平缓。在长江的水很大而洞庭湖四水比较小时,长江对洞庭湖发生很严重的顶托影响,反之洞庭湖对长江发生严重的顶托影响。其次是各河流流入平原的涨落率影响,荆江河道的冲淤影响,以及诸如此类影响是多而且极其复杂。因此摆在我们面前的,无论是测验和整编,及规划中的洪流的演算都是有着相当困难的。几年来在党和行政正确的领导下,对於这一段的预报演算工作虽然有了很多成就。但是我们从事过和正在从事这些工作的同志们,仍然是感到所作的结果,用较高的标准去衡量还是不能令人满意的。兹将我们在中游防洪排渍规划工作中所采用的方法和做出的一些结果提出来与同志们商榷,望能 I. Introduction The Yangtze River out of the Three Gorges, that is, into the plains area. Below the Zhijiang part of Songzhu, Taiping, Ouchi, tune the four sub-flow into the Dongting Lake, part of the discharge along the Jingjiang River, near Yuechengchenglingji with four and Hunan, capital, Yuan, 沣Si Shui Lake Dongting Lake after the convergence of the flow of storage. This section of the river is very gentle drop. When the water in the Yangtze River is large and the water in the Dongting Lake is relatively small, the Yangtze River has a very serious top-supporting effect on Dongting Lake. On the contrary, the Dongting Lake exerts a serious impact on the Yangtze River. The second is the influence of fluctuations in the inflows of the rivers into the plains, the erosion and deposition of the Jingjiang River channels, and so on. The effects are numerous and extremely complex. Therefore, before us, both the test and reorganization, as well as the calculation of the planned torrent, are quite difficult. In the past few years, under the correct leadership of the party and the administration, there have been many achievements in the forecasting and calculation work for this period. However, the comrades who have been engaged in and are engaged in these work are still feeling the result of the work and are still not satisfied with the higher standards. Hereby, we will discuss with some of the methods we have adopted in the planning of flood control and drainage in the middle reaches and some results we have made