关键词: 城市化, 平原河网, 河流结构, 分类方法

Abstract: Stream structure development in river network regions was both affected by physical conditions and rapid urbanization.Based on remote-sensing data,four measuring dimensions including the degree of urbanization,river patterns,stream structure and river functions were brought forward to be used as tools for stream structure classification.Twelve indicators such as the percentage of urbanized area,river length and width distribution,river fractal dimension,river flood storage and control capacities were designed for explaining the four measuring dimensions and describing the characteristics of stream structure type.The characteristics of three kinds of stream structure that were defined as the mainstream type,and the "#" type and the natural type were discussed based on the classification system developed in the paper.The results showed that the mainstream type was formed mainly because of high level of urbanization and branches were engineered out for the sake of urban construction and expanded.The natural type was maintained mostly in the area with lower lever of urbanization,which always reflects the local physical features.The "#" type stream structure was a sort of result caused by intermediate level of urbanization under spatial distribution of mainstreams in a catchment.Generally,following the urbanization process,stream structure might be changed from the natural type to the "#" type and at last,to become the mainstream type.The paper further discussed the qualitative and quantitative criteria that could used to guide differentiating structure status in river network regions.The authors thought it was valuable and important to maintain natural stream structure and plan and restore multi-functions of rivers in the process of urbanization.

Key words: urbanization, river network plain, stream structure, classification system