水文过程与近岸带变化关系及其河流景观内涵

The mapping relation between inshore belt size and hydrologic condition with its connotation in riverine landscape

在河流生态学领域,迄今仍缺乏能较好地描述河流生态系统涨落的概念模型。河流近岸带具有不同于主流带的水动力、水环境及生物特征,其位置及尺度随水文条件的改变而变化的程度较为显著,近岸带变化能较好地反映水文过程的生态学效应及河流水域空间的涨落。本文对近岸带定义进行了拓展,提炼了一种对顺直/微弯、弯曲、分汊等河型均适用、描述河流近岸带尺度变化与水位涨落之间映射关系的概念模型(“水文-近岸带涨落关系”概念模型),该模型曲线上一般具有两个近岸带尺度峰值;从景观生态学的角度提出近岸带是河流水域中时空连续性最强的沿程条带状基质,而主流带可视为流量越过临界值后出现在近岸带这一基质内的“涌现”或“突变”。本文最后以长江上游南溪-江安段为例对概念模型进行了初步的量化研究,并讨论了近岸带的界定方法及该概念模型在生态水文组分划分中的作用。

The conceptual model which could well illustrate the fluctuations of riverine ecosystem is still to be developed.The hydraulic,water environmental,and biological characteristics of the inshore area of a river are distinctly different from those in main stream.The variations of position and size of the inshore belt are relatively obvious compared with those of the main stream,thus the fluctuation of the inshore belt can depict the ecological effects of hydrological process and the variation of the water area better.In this paper,the definition of inshore belt was generalized,and a conceptual model illustrating the mapping relation between the size of inshore belt and the variation of water level was presented,which seems applicable to different channel types such as straight/slightly sinuous,sinuous and braided type.There are two size peaks with the inshore belt on the curve depicting the mapping relation.In the viewpoint of riverine landscape,inshore belt can be regarded as a ribbon-like matrix of water area of a river,with perfect continuity both in time and space span;the main stream belt can be treated as a type of structure emerging from the inshore belt matrix,when the discharge surpasses a critical value.The upper Yangtze River reach from the Nanxi Town to the Jiangan Town was employed as an example to examine the conceptual model,and how to define the inshore belt together with its application in the classification of ecological hydrologic components was discussed finally.