Sounding out our coastlines and rivers

The researchers studying the Rio Paraná and Rio Paraguay river junction found that these two rivers don't mix quickly and the water flow of these large rivers at the river junction is in complete contradiction to that of small rivers. They measured the full three-dimensional shape of the riverbed down to a few millimeters using the latest technology including a RESON SeaBat multibeam echo sounder. The scientists discovered a mighty scour hole, 35m deep, just upstream of the junction itself and recorded sand dunes migrating into, around, and through this huge hole. They also observed that the scour hole and its fast-flowing bottom water actually drive water upwards as the two river flows collide, which is contrary to the findings from the studies of small rivers.