城市化对上海河网结构和功能的发育影响

EFFECT OF URBANIZATION ON GROWTH OF SHANGHAI RIVER FUNCTION AND STREAM STRUCTURE

城市化对河网水系的演变产生了深刻的影响,也使城市化地区水系的界定变得模糊。基于水利片这一城市集排水的基本单元,借鉴上海水务部门河流等级管理系统,探讨了上海河网的结构特征以及城市化对河网发育的影响。研究表明,上海河网发育基本符合水系发育的一般规律;城市化已经成为改变城市地区河网结构发育趋势的主导因素,其影响集中地表现为河网长度发育能力的弱化、河网结构简单化和河道形态的人工化;河网结构与水网功能之间有着密切的关联;水面率、河面率、平均分枝比、平均长度比、单位面积槽蓄容量和单位面积可调蓄容量是上海城市河网结构和功能的主要表征指标。

Urbanization modifies river system, resulting in difficulties to divide watershed in urban areas. Based on water conservancy zones, a concept similar to watershed, this paper analyzed the effect of urbanization on river system evolution in Shanghai and the features of stream structure in accordance with some novel indicators and a large number of local data from Shanghai Water Authority. Horton laws still play important roles in river system evolution in Shanghai, The regional physical characteristics was the base for river system growth. Because of urbanization influence, the ability of stream length development was weaker than the stream area development. Values of some traditional indicators were beyond the general scope, and river function indicators were closely related to structure indicators. The core indicators for describing the river system were the ratio of water area to whole area, the ratio of river cannel area to whole area, the mean ratio of river ramification, the mean ratio of stream length and the river channel storage and the adjustable river channel storage.