What Is a River Source? Definition and Examples

In hydrology, a river’s source is the point where water begins to flow continuously on the land surface. This can be a spring where groundwater emerges, a lake or pond outlet, or the confluence of two or more streams. The source is often marked by a distinct topographic feature—such as a mountain, hill, or a noticeable change in vegetation. The headwaters comprise the uppermost tributaries feeding the main channel, while the watershed (drainage basin) encompasses all land that drains into the river system.