The upper river has the steepest course, with gorges, waterfalls and a bouldery bed. It flows in a narrow, steep-sided V-shaped valley.
In its middle course, the river changes. It is wider and deeper. It flows less quickly, the bouldery bed changes to sand and a flat strip of land appears beside the river. The river begins to twist and turn over this flat land and gives room for people to live and farm.
