基于高分影像的城市黑臭水体遥感识别:以南京为例

Remote Sensing Identification of Urban Black-Odor Water Bodies Based on High-Resolution Images:A Case Study in Nanjing

城市黑臭水体的遥感识别对于黑臭水体的监测、治理有着重要作用.2016年对南京城市河段进行了地面调查,并在沙洲西河、秃尾河、玄武湖、金川河设置了55个样点,采集水样分析水质参数并同步测量水面光谱.在此基础上,利用绿光波段遥感反射率的单波段阈值、蓝、绿波段差值、红、绿波段比值,以及色度值,分别构建了基于GF-2影像的城市黑臭水体遥感识别算法,并分析南京市主城区黑臭水体的空间分布和环境特点.结果表明:(1)和其他类型水体相比,城市黑臭水体遥感反射率最低,在整个可见光范围峰谷不突出,而且在400~550 nm范围光谱斜率最小;(2)采用地面同步调查结果检验,比值算法的识别精度最高,对城市河道黑臭水体的识别更准确;(3)利用比值法对2016年11月3日的GF-2影像进行计算,共提取研究区黑臭河段11条,总长度40.7 km,总面积0.749 km^2.黑臭河段分布具有范围广且不连续的特征,集中分布于各城区人口密集的区域;水体发生黑臭主要受到生活污水、工业废水、断头浜的影响.

The identification of urban black-odor water bodies plays an important role in monitoring and controlling black-odor water bodies.In 2016,a ground survey was conducted on the urban reach of Nanjing,and 55 samples from the West Shazhou River,Tuwei River,Xuanwu Lake,and Jinchuan River were obtained.The spectral characteristics of urban black-odor water bodies and other water bodies were analyzed.Recognition algorithms for GF-2 data were proposed in order to analyze the spatial distribution and environmental factors of urban black-odor water bodies.These algorithms were single-band thresholds based on reflectance of the green band,the difference between the blue band and green band,the ratio of the green band and red band,and the chromaticity value.The results indicate that：（1） compared with other types of water,the urban black-odor water has the smallest spectral slope in the range of 400-500 nm and lowest reflectivity,and the peaks and valleys are not prominent in the whole visible range;（2） based on the verification,the accuracy of the ratio algorithm is the highest;and（3） using the ratio algorithm to calculate the GF-2 data of November 3,2016,a total of 11 black river sections are identified.The entire length is 40.7 km,and the area is 0.749 km^2.The black-odor water sections are distributed over a wide range but are not continuous,and they are concentrated in the densely populated areas.Domestic sewage,industrial waste water,and broken river channel are the main reasons.