The Kafue Flats (locally called Butwa) are a vast area of swamp, open lagoon and seasonally inundated flood-plain on the Kafue River in the Southern, Central and Lusaka provinces of Zambia. They are a shallow flood plain 240 km long and about 50 km wide, flooded to a depth of less than a meter in the rainy season (deeper in some lagoons and permanently swampy areas), and drying out to a clayey black soil in the dry season.