Previous Year Question

A watershed is a geo-hydrological unit in which water received from rainfall or other sources over a defined land area is collected and ultimately drains towards a common outlet, such as a stream, river, lake or another drainage point.

The boundary of a watershed is generally formed by surrounding high land, ridges or drainage divides. Surface runoff falling within the boundary moves towards the same drainage system.

A watershed does not merely channel surface water. Water may also be stored temporarily in—

soil moisture, groundwater, ponds, lakes and other storage components

and later released into streams and rivers.

Therefore, a watershed is also used as a planning unit for soil and water conservation, groundwater recharge, erosion control and rain-fed agriculture.

Among the other options—

A Wetland is a water-saturated ecosystem, but every watershed is not a wetland.
A Wasteland refers to degraded or unproductive land.
A Water reserve refers to stored water, not the entire geographical drainage unit.