What is river catchment?

A river catchment, also known as a drainage basin or watershed, is an area of land that drains water, sediment, and dissolved materials to a common outlet, such as a river, lake, or ocean. The boundary of a catchment is defined by the topography of the land, with water flowing downhill from higher elevations to lower elevations. Catchments can range in size from a few hectares to thousands of square kilometers.

Components of a River Catchment:

1. Precipitation: Catchments receive precipitation in various forms, including rain, snow, and hail.

2. Surface Runoff: When precipitation exceeds the infiltration capacity of the soil, it becomes surface runoff and flows downhill along the land surface.

3. Infiltration and Groundwater Flow: A portion of precipitation infiltrates the soil and becomes groundwater. Groundwater moves through the subsurface materials and can discharge into rivers, lakes, or wetlands within the catchment.

4. Streams and Rivers: Surface runoff and groundwater discharge converge to form streams and rivers. The network of streams and rivers within a catchment collects and transports water towards the main outlet.

5. Vegetation and Land Use: The type of vegetation and land use practices within a catchment affect the water cycle. Forests and natural vegetation promote infiltration and reduce surface runoff, while impervious surfaces, such as urban areas and roads, increase runoff.

6. Erosion and Sediment Transport: Catchments are also influenced by erosion, which is the wearing away of land surfaces by water. Sediment produced by erosion is transported downslope and can impact water quality and aquatic habitats.

The study of river catchments involves hydrology, geomorphology, ecology, and other disciplines to understand water flow, sediment transport, nutrient cycling, and interactions between human activities and the environment. River catchments are important units for water resources management, conservation, and flood control planning.