城市化进程中平原河网地区河流结构特征及其分类方法探讨

River Structure Characteristics and Classification System in River Network Plain During the Course of Urbanization

平原河网地区河流结构发育受到自然条件和城市化的双重影响。依据遥感解译数据,围绕城市化水平、河流形态、河流结构和河流调蓄功能四个维度,就建成区面积比例、河流长宽分布、河系分维、河流调蓄能力等具体指标,分析了城市化水平和土地利用特征不同区域的河流空间形态、结构特征和功能状态,探讨了城市化进程中平原河网地区河流结构的可能演化轨迹,尝试建立了城市化影响下平原河网地区河流结构分类方法,提出了城市河流综合整治过程中应充分重视保护自然河流结构,注重发挥河流综合功能等观点。

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, foUowing 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.