Drainage areas are regions of land that collect and channel water runoff to a particular outlet. In geology, they are often referred to as catchment or watershed areas. These areas play an important role in controlling the flow of water, preventing flooding and erosion. The term hydrological basin can also be used to describe these areas. Drainage basins or river basins are phrases referring to large areas of land that have multiple drainage systems that all feed into a single large river. Overall, synonyms for drainage areas often relate to the collection and conveyance of water and can include drainage basins, hydrological basins, river basins, and catchment or watershed areas.