Application of China's New Generation of ZY1-02E Hyperspectral Satellite in the Inversion of Water Quality Parameters in Inland Waters
The ZY1-02E satellite,launched on December 26 in 2021,carries the new-generation Advanced Hyperspectral Imager(AHSI).It has 166 bands in the visible to shortwave infrared range with a spatial resolution of 30 m,and has con-siderable potential in retrieving water quality parameters in inland waters.This study evaluated the practical application of ZY1-02E AHSI imagery in the retrieval of chlorophyll-a concentration and Secchi-disk depth in the Shahe Reservoir and Jinhai Lake in Beijing,China.Based on the measured data of remote sensing reflectance and chlorophyll-a concentration of 12 lakes and reservoirs in the Beijing-Tianjin-Hebei region,the semi-empirical models for chlorophyll-a retrieval were established.The established chlorophyll-a retrieval model and Secchi-disk depth retrieval model with the Quasi-Analytical Algorithm(QAA)were applied to the ZY1-02E AHSI images,and the accuracy assessment was conducted using the syn-chronized measured in-situ water quality data in Shahe Reservoir and Jinhai Lake.The results showed that the normalized difference index at 670 nm and 705 nm wavelengths based chlorophyll-a concentration retrieval model achieved the highest accuracy,with R2 and mean relative error to be 0.79 and 21.70%,respectively.The QAA-V6 based Secchi-disk depth retrieval model achieved the highest accuracy with R2 and mean relative error to be 0.93 and 13.90%,respectively.These findings preliminarily demonstrated the potential of ZY1-02E hyperspectral data in the retrieval of water quality parameters in inland water.