从理论上深入揭示了江湖关系内在联系及机理, 着重从荆江与分流河道2个方面分析了径流量变化、冲淤及其河道演变的规律。其中在荆江的径流量变化及冲淤方面包括荆江裁弯具有分汊河道的裁弯特性;荆江流量加大引起冲刷;荆江流量加大对三口河道的影响;分流河道与荆江同时冲刷;三峡水库建成后荆江及中下游河段冲刷的平衡时间, 以及监利输沙量变化的估计等。在分流河道演变方面包括分流河道作为三角洲上的河道;季节性河道形成——断流机理;分流引起淤积的原因;分流河道的淤积平衡;分流河道进一步分汊后再淤积;分流河道冲刷时挟沙能力会大幅度减少;三峡水库运行后径流量减少幅度大幅变缓。

It is important to study the internal relationship between Jingjiang River (the middle reach of the Yangtze River) and Dongting Lake in theory. This research includes the runoff variation and rules of erosion and deposition in Jingjiang River, and the fluvial process of three out-flowing streams into the Dongting Lake. First of all, the runoff variation and erosion/deposition in Jingjiang River is presented in the following aspects the characteristics of river cut at the reach of braided channel of Jingjiang River; the discharge flow increment in Jingjiang River has intensified the erosion and has affected the three out-flowing streams; erosion exists simultaneously in the Jingjiang River and the out-flowing streams; the erosion in a certain cross-section of Jingjiang River and its middle-lower reaches achieves equilibrium (which means erosion stops) after the completion of Three Gorges Reservoir construction, and the time of the equilibrium is discussed; the sediment load variation at Jianli station is estimated. Furthermore, in terms of the fluvial process in the three out-flowing streams, the properties of out-flowing streams as channels located on delta is described; the mechanism of zero flow and formation of seasonal stream is analyzed; deposition caused by out-flowing, deposition equilibrium, and deposition of bifurcation channels of the three out-flowing streams are presented; sediment-carrying capacity reduces significantly during the erosion of out-flowing streams; and the decrease of runoff mitigates after the operation of Three Gorges Reservoir.