河口分汊的定量表达及其基本模式

QUANTITATIVE PROPERTIES AND CLASSIFICATION MODELS OF BRANCHING ESTUARIES

本文归纳出河口汊道间的四种交接方式:叉、合、结和口以及相应的十三种联线。并引入拓扑学中有关概念,定量表达点和线间关系。在分析河口汊道体系的拓扑学性质后,重新定义再结合因子,指出其与各种点和线、河口三角洲面积、河口汊道体系的外角等,均有一定的相关关系。在天然河口汊道体系中,最多出现的是点和口,其次是合和结;最多出现的线是fj,ff和fo,最少出现的是kk和ko线。最后,根据成因、形态和冲演特性相结合的原则,将河口分汉分成四个基本模式;少汊型、多汊型、河网型和游荡型分汊河口。并运用分汊河道体系的定量表示法,分析了各分汊模式河口汉道体系的拓扑学性质。

An estuarine branching system has four skinds of vertices, i.e., forks, junctions, knots and outlets, and thirteen kinds of links correspondingly. Some concepts of theory of topology and graphs have been introduced in this paper to make further expression quantitatively to the topo-logic properties of estuarine branching system. After redefining the recombination factor, or the ratio of number of junctions and knots to number of forks, this paper points out the recombination factor varies from zero to one nearly, with the extent of bifurcating and rejoining of an estuary. Ninteen natural branching estuaries have been studied in details. ' The results show us the recombination factor ranging from 0.25 to 0.93, which is related to various kinds of vertices and links, deltaic area, the exterior angle of an estuarine branching system to a certain extent. The most frequently appeared vertices in a natural estuarine branching system are forks and outlets, while links are ff, fj and fo. The most scarcely appeared vertices are knots, while links are kk and ko. Finally, in accordance with the principle to combine the cause, plain feature and channel changing characteristics together of a branching estuary, this paper proposed that four branching models: less-branching, much-branching, complex networks and wandering. The properties of topology of each model have beem studied quantitatively.