What do we call the area where drainage occurs for multiple rivers and their tributaries?

The area where drainage occurs for multiple rivers and their tributaries is referred to as a drainage basin. This term encapsulates the land area that contributes water to a river system, including all the tributaries, streams, and other water channels that feed into the main river. The defining characteristic of a drainage basin is that all precipitation that falls within its boundaries flows into the same water body, making it a crucial concept in hydrology and geography.

Understanding drainage basins is important for several reasons, including water resource management, understanding the hydrological cycle, and assessing environmental impacts like erosion and sediment transport. Each drainage basin is separated from others by ridges or high ground known as watersheds, but it is the drainage basin that specifically refers to the entire system of interconnected waterways. In contrast, terms like delta region refer to landforms created by sediment deposition at the river mouth, and riparian zones indicate the interface between land and a river or stream, focusing on ecological aspects rather than the broader concept of drainage.