根据2009年8月22-24日实测的三峡水库水体的光谱数据以及水质参数,对三峡水库漫衰减系数的光学特性及影响因子进行分析研究,构建了490nm处漫衰减系数的Kd(490)反演模型,并利用环境一号卫星CCD数据对2009年7月21日的三峡水库Kd(490)进行反演.结果表明:由于水体中非色素颗粒物的含量较高,使得研究区大部分点位的Kd值在440nm和675nm处的衰减峰值不明显,对Kd占主导地位的影响因子是颗粒物的吸收作用以及水体的总散射作用,在所选的四个特征波段(440、550、613和675nm)处,其贡献率的均值分别为45.48%和38.21%;在400-700nm波段范围,Kd与非色素颗粒物浓度具有很好的幂函数关系.利用地面实测遥感反射率模拟环境卫星第三波段构建Kd(490)反演模型,其平均相对误差为17.89%,直接利用卫星数据反演的相对误差为28.38%;研究区中Kd(490)主要集中在6-7m-1,占研究区域面积的83.60%,相比而言,入库支流的Kd(490)较干流要低,表明支流颗粒物含量相对较低.
By using the in situ measured data of spectral reflectance and water quality parameters in Aug.22-24,2009,this study analyzed the spectral characteristics and affecting factors of diffuse attenuation coefficient(Kd) of the Three Gorges Reservoir,and built a retrieving model of Kd(490)at band 490nm.In addition,Kd(490)was inversed by using CCD image of HJ-1 satellite in July 21,2009.The results showed that the attenuation peaks were not distinct at bands 440nm and 675nm owing to the high content of non-pigment particulates in the water.The dominant affecting factors were absorption of particulates and total scattering of water body,while average contributions of the four bands(i.e.440,550,613 and 675nm) were 45.48% and 38.21%,respectively;Kd strongly power correlated with the concentration of non-pigment particles between 400 to 700nm.Besides,the average relative error of inversed vs.measured Kd(490) was 17.89% for ground-measured Rrs,whereas the relative error for images data was 28.38%;Kd(490)of the study area was concentrated from 6 to 7m-1,which accounted for 83.60% of the study area.Additionally,Kd(490)of the tributaries of the reservoir was lower than the main stream,which indicated that the content of particulates in tributaries was relatively low.