Flow records for the Okavango River confirm Chief Nxaku's observations: in the past 50 years, the Okavango's annual volume of flow has decreased almost 20 percent.
(the Okavango's annual volume of flow; has decreased; almost 20 percent; T:in the past 50 years) Context(the Okavango 's annual volume of flow has decreased,List([94, 144))):(Flow records for the Okavango River; confirm; Chief Nxaku's observations)
the Okavango 's annual volume of flow has decreased,List([94, 144))
the Okavango's annual volume of flow Flow records for the Okavango River
has decreased confirm
almost 20 percent T:in the past 50 years
Chief Nxaku's observations