How do small streams become part of the river?

Small streams become part of the river through a process called tributary confluence, which occurs when a smaller body of water flows into a larger one. Here's a step-by-step explanation:

1. Rainfall and Runoff: Small streams typically originate from rainfall or melting snow in a specific catchment area or drainage basin. As rainwater falls on the land, it flows down slopes, collecting in low-lying areas and forming small rivulets.

2. Gully Formation: These small rivulets cut channels into the landscape, creating gullies as they flow downhill. The erosive power of water gradually deepens and widens these gullies, transforming them into small streams.

3. Stream Flow and Erosion: As the small streams continue to flow, they erode the surrounding soil, rocks, and sediments. This erosive action further deepens and widens their channels, leading to the formation of larger and deeper streams.

4. Tributary Formation: As these larger streams flow through the landscape, they encounter other smaller streams and rivulets that converge and merge with them. These converging streams are called tributaries.

5. River System: The confluence of multiple tributaries with the larger stream eventually leads to the formation of a river system. The river serves as the main channel that collects water from its tributaries and carries it downstream towards larger bodies of water, such as lakes, oceans, or other rivers.

In summary, small streams become part of the river through the joining of tributaries. The process involves the collection of rainwater and runoff, the formation of small channels and gullies, the merging of these channels into larger streams, and the convergence of multiple tributaries to form a river network.