The scientists studied how water flows over different types of riverbeds with plants growing on the walls. They wanted to see how the speed and force of the water changed in these conditions. They found that the speed of the water was highest near the surface in the pool areas and near the bottom in the riffle areas. The strongest force of the water was in the pool areas, while the weakest force was in the riffle areas. They also discovered that the location of the fastest water changed with the amount of water flowing. When the rocks on the riverbed were smaller, the force of the water didn't change as much.