网状河流研究进展述评

The Progress in the Research of Anastomosing River

网状河流作为一种新的冲积河流类型已经引起地貌学家、水利学家和沉积学家的关注 ,成为河流地貌领域、河流沉积领域以及河流水动力领域的研究热点之一。本文在介绍网状河流基本概念的基础上 ,综合国内外的研究成果 ,从河流的平面形态、边界条件、沉积特征、水动力条件以及在河型演化序列中的位置等方面 ,对网状河流的研究进展作一较全面的述评 ,并指出目前研究的薄弱环节 ,以利于研究者把握网状河流的研究现状 ,并推动对网状河流的进一步探讨。

Anastomosing river, as a new fluvial river pattern, has attracted more and more attention of geomorphologists, hydraulic engineers and sedimentologists. Research on anastomosing river is in great demand of the geomorphology, hydraulic engineering and sedimentology. In this paper, after introduction of the basic concept of anastomosing river, the channel plantform and boundary condition, sedimentary characteristics, hydraulic condition of this river pattern are reviewed based on comprehensive references. Furthermore, in the same fluvial system the spatial transformation between anastomosing and another river patterns is also discussed. Some weaknesses and aspects needing more attention on study of anastomosing river are pointed out. These aspects are mainly following. (a) The dynamical mechanism of the avulsion for anastomosing river formation has not studied clearly till now. It needs theoretical explanation and simulation in laboratory or digital model. Obviously, there have some difficulties. (b) The hydraulic dynamics of anastomosing rivers are still unclear because few study has been actualized on fluvial dynamics for multiple channel rivers, especially for anastomosing rivers. Besides, the hydraulic characteristics have some differences between multiple channels. The explanation to every channel of an anastomosing river system is not the same always. The stream power (including gross stream power and specific stream power) is also different between different channels of an anastomosing river system. (c) The scatter values of channel slope and bankfull discharge for anastomosing rivers have not a clear law. One of the causes is that the river number studied fully by researchers is few and distributed in different climate zones. This demands researchers to study much more anastomosing rivers.