摘要:针对平原河网地区水系形态难以刻画并且受城市化的空间影响难以定量等问题，以太湖平原杭嘉湖地区为例，基于地形图获取的1980s与2010s水系数据和遥感影像等资料，运用多重分形理论及地理加权回归模型，定量揭示了20世纪80年代以来城市发展对河网水系演变的影响。结果表明：（1）杭嘉湖地区河网密度和水面率均呈减小趋势，衰减率分别为10%、13%；区内水系分布集中，均匀性下降；河流曲度降幅为0.5%，干流面积长度比在中、高城市化区域增幅较大。（2）水系变化对城市化的响应在空间上存在较为明显的异质性。城市化水平越低，水系形态演变越剧烈，空间分布不规则性越明显。（3）杭嘉湖地区存在"低-低"、"低-中"、"低-高"、"中-高"4种不同的城市化水平转变类型。城市化水平未发生转变时，水面率衰减更为剧烈，且水系空间分布均匀性下降，水系形态变化较大；城市化水平转变幅度越大，水系均匀化分布趋势越明显；受政策影响"中-高"发展区域仅河网密度变化较为明显。本研究将为城市河网水系保护和生态环境可持续发展提供科学参考。



Abstract:With the rapid development of urbanization, the river network morphology in the plain area is harder to describe, not to mention the difficulty in quantifying the spatial influence of urbanization. Based on the data of river network in the 1980s and 2010s obtained by topographic map and the data of LUCC from remote sensing images, this paper quantitatively reveals the impact of urbanization on the river network since 1980s in the Hangzhou-Jiaxing-Huzhou area of Taihu Lake Plain with the application of multifractal theory and geographically weighted regression model. The results show that: (1) both the density and water surface ratio of river network present a decreasing trend, and their attenuation rates are 10% and 13%, respectively. From the multifractal perspective, the distribution of the river network was concentrated and the uniformity was decreased. Besides, the river sinuosity decreased by 0.5%, and the main river area length ratio increased significantly in the moderately and highly urbanized areas. (2) The response of river network evolution to urbanization has obvious heterogeneity in space. The lower the urbanization level is, the greater the evolution of river network morphology is, and the more obvious the irregularity of spatial distribution is. (3) There are four different types of urbanization level transformation in Hangzhou-Jiaxing-Huzhou region: low-low, low-moderate, low-high, and moderate-high. When the urbanization level does not change, the spatial distribution uniformity decreases, the river network morphology changes greatly and the attenuation of water surface ratio is greater. Furthermore, the greater the transformation is, the more obvious the homogenization trend of river network distribution is. Due to the effects of policy, only river network density changes significantly in the moderate-high development area. This study will provide scientific support for the sustainable development of ecological environment, so as to protect the river network.





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