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Chinese Gaofen-3 (GF-3) satellite is a spaceborne multi-polarisation synthetic aperture radar (SAR) mission in C-band and it can be applied in the multiple fields. GF-3 can achieve accurate water boundary extraction based on its high-resolution SAR image products. This paper will study GF-3's capability to extract water boundary. Danjiangkou reservoir, the largest artificial freshwater lake in Asia and water source of Chinese South-to-North Water Diversion Project, is selected as the study region. A novel segmentation method is proposed which consists of two parts: the first part is rough segmentation to get the initial boundary; the second part is fine segmentation to get the final water boundary. Experimental results show that GF-3 has good performance in water boundary exaction by virtue of this novel method.

Chinese Gaofen-3 (GF-3) satellite is a spaceborne multi-polarisation synthetic aperture radar (SAR) mission in C-band and it can be applied in the multiple fields. GF-3 can achieve accurate water boundary extraction based on its high-resolution SAR image products. This paper will study GF-3's capability to extract water boundary. Danjiangkou reservoir, the largest artificial freshwater lake in Asia and water source of Chinese South-to-North Water Diversion Project, is selected as the study region. A novel segmentation method is proposed which consists of two parts: the first part is rough segmentation to get the initial boundary; the second part is fine segmentation to get the final water boundary. Experimental results show that GF-3 has good performance in water boundary exaction by virtue of this novel method. [ABSTRACT FROM AUTHOR]

The construction of a high-resolution dynamic water storage model, driven by the mass load of the huge water storage of the Three Gorges Reservoir (TGR), is the necessary basic data for accurately simulating changes in the geophysical field, e.g., gravity, crustal deformation, and stress. However, previously established models cannot meet the needs of accurately simulating the impoundment effects of TGR, because these models were simplified and approximated and did not consider the variation of river boundaries caused by water level changes. In this study, we combined high-resolution Gaofen-1 (GF-1) satellite imageries and real-time water level in front of the dam and extracted 31 river boundaries of the head region of TGR between the lowest (145 m) and the highest (175 m) impoundment stages based on the Normalized Differential Water Index (NDWI) and threshold segmentation from Otsu method. Developed dynamic water storage model based on higher-resolution GF-1 data can show the true river boundary changes more exactly, especially in local areas. Compared to the previous approximate models, the model that we constructed accurately depicts the boundary distribution information of the different impoundment stages. Moreover, we simulated TGR-induced gravitational effects based on the high-precision forward modeling of the dynamic water storage model (i.e., considering changes of dynamic water area and water level). The theoretical modelled results are consistent with in situ gravity measurements with the difference mainly within 10 μGal. Our results indicate that water storage variations of TGR mainly affect the gravity field response within 1000 m of the reservoir bank with its maximum amplitude up to several hundred μGal. The dynamic water storage and its simulation results of gravitational effects can effectively eliminate the impact of surface water load driven by the TGR under human control and greatly improve the signal-to-noise ratio of regional gravity observational data. Thus, this work will be beneficial in the application of geophysical and geodetic monitoring aimed to comprehensively track the local and regional geological structural stability, e.g., artificial reservoir induced earthquake and landslide.

The construction of a high-resolution dynamic water storage model, driven by the mass load of the huge water storage of the Three Gorges Reservoir (TGR), is the necessary basic data for accurately simulating changes in the geophysical field, e.g., gravity, crustal deformation, and stress. However, previously established models cannot meet the needs of accurately simulating the impoundment effects of TGR, because these models were simplified and approximated and did not consider the variation of river boundaries caused by water level changes. In this study, we combined high-resolution Gaofen-1 (GF-1) satellite imageries and real-time water level in front of the dam and extracted 31 river boundaries of the head region of TGR between the lowest (145 m) and the highest (175 m) impoundment stages based on the Normalized Differential Water Index (NDWI) and threshold segmentation from Otsu method. Developed dynamic water storage model based on higher-resolution GF-1 data can show the true river boundary changes more exactly, especially in local areas. Compared to the previous approximate models, the model that we constructed accurately depicts the boundary distribution information of the different impoundment stages. Moreover, we simulated TGR-induced gravitational effects based on the high-precision forward modeling of the dynamic water storage model (i.e., considering changes of dynamic water area and water level). The theoretical modelled results are consistent with in situ gravity measurements with the difference mainly within 10 μGal. Our results indicate that water storage variations of TGR mainly affect the gravity field response within 1000 m of the reservoir bank with its maximum amplitude up to several hundred μGal. The dynamic water storage and its simulation results of gravitational effects can effectively eliminate the impact of surface water load driven by the TGR under human control and greatly improve the signal-to-noise ratio of regional gravity observational data. Thus, this work will be beneficial in the application of geophysical and geodetic monitoring aimed to comprehensively track the local and regional geological structural stability, e.g., artificial reservoir induced earthquake and landslide. [ABSTRACT FROM AUTHOR]