Final answer:
The numbered areas mentioned in the question are best described as River Basins. River basins refer to the land area drained by a river and its tributaries.
Step-by-step explanation:
The numbered areas mentioned in the question are best described as River Basins. River basins refer to the land area drained by a river and its tributaries. They play a crucial role in the water cycle and influence the distribution of water resources and ecosystems.