evidence: Technocrats from the two countries are quietly working to head off a dispute as River Semliki, which defines part of their common frontier, rapidly changes course. [...] Randomly ceding huge chunks of territory in a wild give and take, the Semliki River has changed course so much over the past half-century that it has transferred as much as 50 square kilometres of Congolese territory to Uganda. [...] Seen as a permanent feature back then, the Semliki, which flows through Semliki National Park in Uganda before draining into Lake Albert, was used to define part of the border between Belgian Congo and Uganda in the late 19th century.