利用中巴地球资源卫星数据反演武汉市湖泊营养状态指数

以武汉市主要湖泊为例，研究了利用中巴地球资源卫星（CBERS2）数据反演水体营养状态指数（TLI）。研究旨在评估利用中巴地球资源卫星数据来估算内陆水体富营养化程度的可能性。首先利用地面水质监测数据计算武汉市某些湖泊监测点的“真实的”营养状态指数（包括综合营养状态指数和修正的Carlson营养状态指数），同时，在事先经过辐射校正和几何校正的CBERS2图像上，以9×9像元为采样窗口，提取各个对应地点的灰度值均值（从波段1至波段4）；然后，采用多元逐步回归分析，以各波段灰度值均值为自变量，建立营养状态指数经验遥感反演模型；最后，利用模型对整个湖泊水体的营养化状态指数进行反演，并绘制了其空间分布图。 结果显示，营养状态指数的自然对数值与CBERS2图像各波段灰度值之间存在较好相关关系，回归系数平方值(R²)为0.51。利用反演模型反演得到的湖区水质分布与实际情况基本相符。由于CBERS2图像数据可以从我国许多数据分发中心免费获取，这为低成本的水质遥感监测提供了一条途径。

ESTIMATING TROPHIC LEVEL INDEXES OF LAKES IN WUHAN BY USING CBERS-2 IMAGE

A study case for retrieving trophic level index of water body of lakes in Wuhan,Hubei Province,using CBERS-2 images data was presented.The aim of this study is to evaluate the probability of CBERS-2 images data on estimating the eutrophic level of inland water.At first step,the "real" TLI (both aggregative trophic level index (TLI) and revision carlson index (TSIM)) at the observation spots of some lakes in Wuhan were calculated using the monitoring water quality data.In the mean time,the mean grey values of a 9×9 pixels sampling window for band1-band4 at the corresponding spots were obtained and calculated from the CBERS-2 image which had been taken radiometric calibration and geometric correction beforehand.After that,an experience inversion model for TLI had been built through multivariate regression using the mean grey values of each band as independent variables.Finally,the TLI of all water bodies were inversed with this model and a map for its spatial distribution was drawn up.Results demonstrate that there are good correlation relationships between the natural logarithm values of TLI and spectral reflectance of CBERS-2 image,the square regression coefficients (R~2)is about 0.51.The distribution of inversed TLI of the lakes fixes the reality quite well.This might provide us a cheap way for monitoring inland water quality since CBERS-2 images data can be obtained freely from many data delivering centers in China.