Definition:
A "drainage basin" is a large area of land where all the water that falls as rain or snow collects and flows into a single river or stream. It can also be referred to as a watershed or catchment area. Essentially, when it rains, the water from that area will eventually flow to a common place, like a river.
In advanced contexts, you might discuss the effects of human activities on drainage basins, such as urbanization or deforestation, which can lead to flooding or changes in water quality.
While there are no specific idioms or phrasal verbs directly related to "drainage basin," you may encounter phrases like: - "Catch the rain" - This can refer to collecting rainwater, often in the context of managing water resources within a drainage basin.
A drainage basin is an important concept in understanding how water moves across the landscape.