基于极化SAR的河流有机物污染监测研究

Monitoring of Organic Pollutants in River Based on Polarimetric SAR

选择我国南方水质变化梯度较为明显的典型河流为对象,分析基于C波段极化合成孔径雷达(极化SAR)的河流水污染监测评估技术.引入了随机粗糙面电磁散射理论对污染水域的散射特性进行了建模,研究了水体污染可能对散射模型及参数的影响,分析了同步得到的极化SAR数据与水体常用污染指标的监测数据.通过比较19个采样点的后向散射系数与同步监测的水质指标,发现化学需氧量(COD)与HH和VV通道的后向散射系数比成正相关性,这与由电磁理论建立的散射模型及水体污染对散射模型参数影响的分析相符.利用最小二乘法,拟合得到了利用HH与VV通道后向散射系数比来反演化学需氧量的公式,拟合结果的相关系数达到0.90.本研究建立了利用极化SAR的HH与VV通道后向散射系数比监测水体有机物污染的模型,该模型主要通过分析同步监测数据获得,基于电磁散射理论的分析支持了该模型的有效性.

The rivers with the distinct gradient of water quality in the southern region of China were selected as a case study.The objective of this study was to develop the monitoring and evaluating technology of the water quality based on C-band polarimetric synthetic aperture radar（POLSAR）.The random rough surface scattering model to describe the electromagnetic scattering characteristics of polluted water was briefly introduced.The potential effect of organic pollutants to the scattering model and backscattering coefficient were explored.The simultaneously obtained POLSAR data and the measured water quality indexes were analyzed.By comparing the POLSAR data and the water quality indexes,it could be observed that the chemical oxygen demand（COD） was in proportional to the ratio between HH and VV backscattering coefficients,which matched the analysis based on electromagnetic scattering theory.A fitting model was proposed to retrieve the chemical oxygen demand by ratio between HH and VV channel backscattering coefficients using least square method,with the fit coefficient of 0.90.In this study,the model using the ratio between HH and VV backscattering coefficients was established,which was mainly based on the analysis of experimental results,and was also supported by theoretical interpretation.