Precise determination of sediment dynamics using low-cost GPS-floaters

For many water engineering tasks, precise information about the water flow characteristics is required to model discharge and sediment transport. In many cases, the Global Positioning System (GPS) is used to measure floater trajectories and to derive flow velocities indirectly from floater positions. In this paper, we describe a new GPS-based measurement system that avoids the use of expensive equipment and which uses a direct velocity determination approach. Despite its low costs, the new floater system achieves position accuracies of several meters and accuracies of about 5 cm/s for velocities. We describe both hardware and software details of the new system. Results from a first measurement campaign show the system's capabilities for hydrometric applications.