河网城市不透水面的河流水质响应阈值与尺度效应研究

河网城市持续扩展的不透水面显著影响区域环境水文过程。本文以上海地区为例构建河网城市的研究方案，以水环境断面缓冲区为多尺度水文单元，对区域水环境质量与总不透水面（TIA）之间的响应关系进行研究。结果表明：区域总不透水面比率（PTIA）与主要水质指标之间呈现出非线性相关关系，存在阈值效应（PTIA=60%）。 当PTIA<60% ，水环境质量与PTIA未有明显关联关系；当PTIA>60% ，水环境质量随PTIA增加呈显著指数上升趋势；区域总不透水面比率与水中的溶解氧（DO）之间表现为简单的线性响应关系，随PTIA增加而单调递减；TIA 与区域水环境质量间阈值效应没有呈现明显的尺度效应，从河岸带尺度到最大缓冲区尺度内，不同汇水单元尺度下的阈值效应十分接近。

Threshold and scaling effect of impervious surface impact on stream water quality in city with river networks

Rapid expanding of urban impervious surface in cities with river networks has generated a notable impact on the regional environ-hydrological process.Discussion on the water quality response of impervious surface is of great importance for the regional land use regulation and river management.Considering the special hydro-geomorphic characteristics of city with river network,Shanghai was selected as the study area.Based on the 48 water environmental monitoring cross-sections,a serial of buffers in different spatial scale from 100m to 1 500m were established surrounding each cross-section,which would be used as hydrological units to detect the scaling effect.It demonstrated that there was a clear non-linear relationship between TIA(Total Impervious Area) percentage and water quality index,and the threshold effect was clearly verified for these indices,with a common threshold(TIA=60%).However,there was a simple linear relationship and not any threshold effect between TIA percentage and DO(Dissolved Oxygen).The sudden change of different water quality index was different when TIA exceeded the threshold,especially the pollution of NH3-N and TN were the most.At the same time,the results were also proved that the threshold effect was independent of the scaling.