Rivers begin in upland areas and flow downhill towards the sea.

The start of a river is called the Source and the end is called the Mouth.

Along the main river, there are many other smaller rivers which join it called Tributaries. These join with the main river at a point called the Confluence.

A river and its tributaries obtain their water from the surrounding land. The area drained by the river and its tributaries is called the Drainage Basis. The boundary of the drainage basin is called the Watershed.

The long profile of a river is a cross-section from the source to the mouth. It consists of three sections:

Upper section – narrow, steep-sided valleys (v-shaped) where gorges and waterfalls may form

Middle section – wider valley with floodplain but still with steep valley sides

Lower section – very wide, flat-floored valley with meanders and ox-bow lakes

Here is a short video showing you the journey from source to mouth of the river.