 The main problem of both the Belgian and British sides over the southeast Katanga border was the lack of an obvious geographical feature for the border to follow, as the Congo-Zambezi watershed and the Luapula do not meet.There is a gap between them and, separated by a distance of , they run in an arc curving northeast, running almost parallel but gradually getting closer, and would reach the highlands between Lakes Tanganyika and Nyasa if the Chambeshi River were accepted as being the same river as the Luapula.From the British point of view, the obvious choice for the border is the base of the salient, a southwest to northeast line from the watershed to the Luapula.