Using Optical Satellite Images and Satellite Altimetry Data to Estimate Volume Variations in Dams

Abstract

Abstract. This study focused on monitoring the water volume variations of the Doroudzan dam reservoir in Shiraz, Iran, using satellite observations. In particular, Sentinel-3 altimetry mission (SRAL) Level-1B and Level-2 data were employed to calculate water level changes, addressing the limitations in accuracy for inland and shallow waters. Re-tracking of returned waveforms was applied to improve the accuracy of Level-2 altimetry results. Additionally, Sentinel-2 optical images were utilized to monitor the water surface area of the dam reservoir. The results demonstrated that re-tracking the returned waveforms significantly improved the water level observations compared to Level-2 data. The analysis extended to comparing the time series of water surface area estimated from Sentinel-2 images with in-situ data, revealing a high accuracy of 5.39%. Combining optimum water level and surface area data in Heron's equation facilitated the calculation of water volume variations. A remarkable correlation of 95.27% was found when comparing the time series of estimated water volume variations and in-situ data. This study underscores the effectiveness of Copernicus satellites, particularly Sentinel-3 and Sentinel-2 missions, in monitoring inland water bodies and demonstrates the reliability of the techniques employed for tracking dam reservoir volume variations.