Question

Which is the area of land from which a stream collects runoff? A. drainage basin C. runoff B. gully D. stream channel

Short answer

The area of land from which a stream collects runoff is called a drainage basin.

Step-by-step solution

Understand the Question

We need to find the term that describes the area of land from which a stream collects its runoff. Essentially, this term refers to the geographical area that contributes water, either in the form of rainfall or snowmelt, to a particular stream.

Definition of Terms

Let's define each option to see which one matches the given description: - **A. Drainage Basin**: This is an area of land where precipitation collects and drains off into a common outlet, like a river, bay, or other body of water. - **B. Gully**: This is a landform created by running water eroding sharply into soil, typically on a smaller scale than a drainage basin. - **C. Runoff**: This refers to the flow of water, typically from rain or other sources, that travels over the land surface and into streams but is not limited to a specific area of terrain. - **D. Stream Channel**: This is the physical confine of a river or stream, consisting of a channel bed and banks, through which the stream flows.

Match Definition to Question

The term that best describes "the area of land from which a stream collects runoff" is a **Drainage Basin**. This term accurately matches the question by referring to the geographical area that directs water towards a stream.

Key concepts

Runoff

Runoff is the movement of water, primarily due to precipitation, that flows over the earth's surface and often into water bodies like rivers and streams. Runoff occurs when rain or snowmelt is unable to fully soak into the ground. Instead, it travels across the land, transporting nutrients, soil, and sometimes pollutants
along the way. This process is crucial for replenishing water bodies and maintaining the water cycle.

• Key Characteristics: It is primarily surface water that moves across expansive areas.
• Causes: Runoff can result from heavy rainfall, melting snow, or excess irrigation activities.
• Environmental Impact: While necessary, excessive runoff can lead to erosion and transport contaminants into waterways.

Understanding runoff helps in managing water resources better and controlling issues like flooding and water pollution.

Stream Channel

A stream channel is the pathway through which a stream or river flows. This channel is typically bounded by banks and has a bed that supports the flowing water. The shape and size of a stream channel are influenced by the water volume,
the surrounding landscape, and the geological features of the area. It plays a significant role in directing water flow and controlling the speed and volume of the stream.

• Structure: Composed of a bed and banks that confine the water.
• Dynamics: The channel can change shape over time due to erosion and sediment deposition.
• Ecological Role: Stream channels often support diverse ecosystems of plants and animals.

Stream channels are important for understanding flood dynamics and conserving aquatic habitats.

Gully

A gully is a formation created by the erosion process caused by running water. Over time, water flowing across the surface sculpts these narrow channels into the earth, deepening them with each flow.
Although gullies are smaller than drainage basins, they can significantly impact the landscape and the surrounding ecosystem.

• Formation: Gullies form when water concentrates in one path, eroding soil vigorously.
• Size: Larger than rills but smaller than full stream channels.
• Environmental Effects: Can lead to loss of fertile soil and affect the stability of surrounding land.

Managing and preventing gully formation is vital in agriculture and land development to prevent land degradation.