sentences:  The delta of the Zambezi is today about half as broad as it was before the construction of the Kariba and Cahora Bassa dams controlled the seasonal variations in the flow rate of the river.Before the dams were built seasonal flooding of the Zambezi had quite a different impact on the ecosystems of the delta from today as it brought nutritious fresh water down to the Indian Ocean coastal wetlands.The lower Zambezi experienced a small flood surge early in the dry season as rain in the Gwembe catchment and north-eastern Zimbabwe rushed through while rain in the Upper Zambezi, Kafue, and Lake Malawi basins, and Luangwa to a lesser extent, is held back by swamps and floodplains.