Development of a GPS-GPRS tracked surface drifter for monitoring of surface currents in tidally dominated estuaries

The Vembanad estuary is one of the largest estuarine systems in India, heavily influenced by monsoonal variations and coastal dynamics. As industrial development and navigation activities increase in the region, understanding the estuary's circulation patterns, predominantly driven by tidal currents, has become crucial. This is essential for assessing the dispersal of industrial waste, sediment transport and ensuring safe and efficient navigation for meeting any disaster preparedness. However, collecting precise circulation data near shorelines remains difficult with traditional field deploying current meters and satellite altimeters due to different logistic challenges and land-sea interactions respectively. Additionally, advanced instruments such as Acoustic Doppler Current Profilers (ADCPs) are not well-suited for shallow water environments. To address this challenge, an indigenously developed surface drifter, based on the Lagrangian technique, has been designed and tested for real-time monitoring of circulation and tidal currents in the estuary. The drifter is equipped with a GPS (Global Positioning System) module and a GPRS (General Packet Radio Service) module, allowing for real-time tracking. By analyzing GPS data collected at regular intervals, current patterns in the estuarine region can be effectively studied. A comparison between current flow patterns measured by the surface drifter and an in situ current meter demonstrated a strong correlation, validating the drifter’s accuracy in capturing estuarine circulation data which signifies the utility of such devices for remotely monitoring.