A drainage basin, also known as a watershed or catchment area, is a fundamental concept in geography and hydrology. It represents an area of land where all surface water from precipitation eventually flows to a single outlet point.
The water in a drainage basin comes from various sources. Precipitation in the form of rainfall is the most common source. In mountainous regions, melting snow and ice contribute significantly to water flow. All this water eventually becomes surface runoff that flows downhill toward the basin's outlet.
Water in a drainage basin follows the natural topography, flowing downhill due to gravity. Small streams merge into larger tributaries, which then join the main river channel. The watershed divide marks the boundary of the basin, separating it from adjacent drainage areas. All water within this boundary eventually converges at a single outlet point.
The water collected in a drainage basin flows to various types of outlets. These destinations include natural features like rivers, lakes, and oceans, as well as human-made structures like reservoirs. Wetlands also serve as important water collection points. Each type of outlet plays a crucial role in the water cycle and ecosystem management.
Watershed divides are the boundaries that separate different drainage basins. These divides typically follow ridge lines and mountain peaks, directing water flow to different outlets. Water falling on one side of the divide flows to one basin, while water on the other side flows to a completely different basin. Understanding these boundaries is crucial for water resource management and environmental planning.