河流5区分段方法与长江干流分段实践

基于Schumm河流分区理论与笔者“最大5河段分段法”，优化提出了“河流5区分段法”，即以流域分区为主导(“体”)，以干流河道分段为目标(“用”)，先按照河源、上游、中游、下游和河口5区进行流域分区，后选取河势和(或)汇流控制节点进行干流河道分段，综合确定合适的河流分段数;基于10大江河分段实践，检验了“河流5区分段法”。长江干流分段实践可总结为兼顾流域与河道特性、流域特性主导和河道特性主导3类分段方法;基于“河流5区分段法”，长江干流推荐划分为5段(长江源—直门达/巴塘河口—宜昌—湖口—徐六泾—长江口)、3段(长江源—宜昌—湖口—长江口)和2段(长江源—宜昌—长江口);长江干流其他分段方法分别基于河流名称、水系划分、行政区界、河流指标和专业管理等。

Method of River Segmentation with Five Subzones and Its Application to the Changjiang River Segmentation

On the basis of Schumm's theory of river subsections and the method of river segmentation with a maximum of five reaches proposed by the author earlier,we present an optimized method of river segmentation with five subzones.Subzoning of watershed is regarded as essence and segmentation of main channel as objective.Watershed is partitioned into five subzones in line with river source,upstream,middle stream,downstream and estuary.Subsequently,the main channel is segmented according to selected knickpoints of river regime and/or tributary confluence,hence the proper number of river segments can be determined.The present method is verified through comparison with the segmentation practices of ten large rivers worldwide,among which the methods for the Changjiang River segmentation can be classified as watershed-and-channel dominated,watershed-feature dominated,and channel-feature dominated.Furthermore,by using the present method,we recommend to divide the Changjiang River into five segments as river source-Zhimenda/Batang river estuary-Yichang-Hukou-Xuliujing-Changjiang River estuary;or three segments as river source-Yichang-Hukou-Changjiang River estuary;or two segments as river sourceYichang-Changjiang River estuary.We also summarized other methods for the segmentation of mainstream Changjiang River,which are based on conventional river names for reaches,confluences of sub-basins divisions,administration zones,river index and professional management etc.