The part of a river where the influence of low and high tide is noticeable, is called the lower river. The upper river is the part of the river where there is no influence of the tides.
When the water level of a river drops, it’s called falling. The water’s dropping or falling. A rising water level (or: rising water) of a river is called flooding.
A “hang” is the outer bend in a river. This one is being polished out by the current. The hang is therefore usually the deep part of the river where there is a lot of current. An “oord” is the inside bend in a river. The river’s sediment will end up in an oord. The oord is therefore the shallow part of the river where there is little current. This shallow area is also called “ground”.
The right bank of a river is the starboard bank when you are sailing, so from the source towards the sea.
The left bank of a river is the port bank when you are sailing, so from the source towards the sea.