Development of an Integrated Satellite-Based Estimation Method for Water Transparency and Algal Beds in the Mekong River

This study presents an integrated satellite-based approach for estimating water transparency and algal bed distribution in the dynamic environment of the Mekong River using satellite imagery. Recognizing that previous research has predominantly focused on marine settings, this work addresses the unique challenges inherent in riverine systems like the Mekong, where low and variable transparency demands specialized techniques. Utilizing Sentinel-2 satellite data, a system was developed that compensates for water depth effects through the Bottom Index—a metric derived from the reflective properties of the riverbed. This approach effectively minimizes the influence of water depth variability on remote sensing data and enhances the accuracy of bottom characterization. Concurrently, water transparency is estimated via a ratio-based statistical model that correlates reflectance values from two selected bands to compute the Secchi-Disk Depth. Field experiments conducted in both coastal waters demonstrated that the estimated results align with in situ observations in algal bed distribution.