Distributaries
Explanation
In the lower course of a river, as it approaches a standing body of water such as a sea or a lake, the gradient of the land becomes extremely gentle. This reduction in slope causes the river's velocity to decrease significantly, leading to the deposition of the sediment load carried by the water. This deposition often obstructs the main channel, forcing the river to split into multiple smaller channels to bypass the sediment barriers and reach the sea.
Option Analysis
- Tributaries is incorrect: Tributaries are smaller streams that flow into and join a larger main river. They are characteristic of the upper and middle courses of a river system and contribute water to the main channel (e.g., the Yamuna is a tributary of the Ganga).
- Distributaries is correct: Distributaries are channels that branch off and flow away from the main river. They are typically found in the lower course, especially in delta regions, where the river divides into a network of streams before entering the sea (e.g., the Hooghly is a distributary of the Ganga).
- Canals is incorrect: Canals are artificial, man-made waterways constructed for purposes such as irrigation, navigation, or drainage. They are not natural geomorphic features resulting from river evolution.
- Estuaries is incorrect: An Estuary is a funnel-shaped mouth of a river where freshwater meets and mixes with saltwater from the sea. While it is a coastal feature, it typically involves a single, widened channel submerged by high tides, rather than a river splitting into multiple streams.
Key Takeaway: A tributary joins the main river and adds water to it, whereas a distributary branches away from the main river and distributes water, typically forming a delta.