The Okavango River receives its water from the high rainfall Angolan highlands far to the north. The forested floodplain is about 10 km wide where it enters Botswana. The Okavango then enters a rift basin, which allows the river to spread out and form the wetland. The width of the rift determines the dimensions of the delta - 150 km from the apex to the downstream margin. The channels carry sediment from the Okavango River that is deposited within the rift basin. Over time, a fan-shaped morphology of deposits has developed, leading to characterization of the wetland as the Okavango "delta".