Comparison of Water Level Changes in the Mekong River Using Gnss Reflectometry, Satellite Altimetry and in-Situ Tide/River Gauges

This study presents the potential of GNSS Reflectometry (GNSS-R) for the monitoring of water levels in the Mekong river delta (Vietnam). A geodetic GNSS station was installed at the Tran De port, Soc Trang province, over 23–30 August 2016. The method used to retrieve water levels from GNSS-R data is based on the Interference Pattern Technic of the Signal-to-Noise Ratio (SNR). To validate our measurements, we used different radar altimetry data from Jason-2, SARAL, Jason-3 and Sentinel-3A missions during the same period for measuring sea surface height (SSH) and in-situ tide gauge station as reference for both tides and floods. The aim of this study is to evaluate the performances GNSS-R, in complex environment, for monitoring at the same time river/tide stages and the possibility to use this technique for calibration/validation of altimetry data. Early results show the good agreement between in -situ gauge and GNSS-R based estimates with correlations which reach ~ 0.85.