The Chambeshi begins as rivulets in the Mbala and Isoka highlands, the broken uplands that form Zambia's northern tier near the Tanzanian border. At 1,760 meters the air is cool, the rainfall generous, and the streams quickly find each other. The river descends the plateau, meanders across miombo woodland and patches of dambo wetland, and swings west. For more than 100 kilometers east of the town of Kasama the Chambeshi is not really a river at all in the usual sense - it is a maze of channels wandering through a floodplain up to 25 kilometers wide, with a wetland core about 2 kilometers across. The Tazara Railway bridge north of Mpika is one of the few places where the river is briefly pinned to a single main channel, 100 meters wide in the dry season and up to 400 meters wide in flood.

The Chambeshi empties into one of the strangest hydrological features in Africa: the Bangweulu Wetlands, a vast seasonally flooded basin that includes Lake Bangweulu and enormous surrounding swamps. This was the country where the explorer David Livingstone died in 1873, searching - wrongly, as it turned out - for the source of the Nile. By the end of each rainy season in May, the Chambeshi has delivered a flood that recharges the wetlands and spills across the Zambezian grasslands to the southeast. Water then emerges from the far side of the swamp under a different name entirely. The Luapula flows out of Bangweulu, heads north along the Congolese border, and eventually joins the Lualaba to become the main stem of the Congo. The river system, in other words, changes its name twice before it reaches its final identity.

The naming - Chambeshi, then Luapula, then eventually Congo - is a reminder that rivers as we map them are creations of colonial geographers and their surveys. The Bemba who lived along the upper river called what they saw. The Lunda on the lower Luapula called what they saw. These were separate waters to separate peoples, even if the hydrology ties them all together. Only when European explorers in the nineteenth century began measuring sources and flows did it become possible, or necessary, to say that a stream in the Zambian highlands was the beginning of a river 4,700 kilometers long that emptied into the Atlantic. The Chambeshi is still, first and foremost, a Zambian river - the water that floods the dambos near Kasama, the water the Tazara Railway crosses on its way to Tanzania, the water the Chambeshi Monument stands beside.

From cruise altitude the Chambeshi is mostly invisible in the dry season - a thin silver thread lost in green miombo country. In the wet season it transforms completely. The floodplain east of Kasama spreads into a shining lattice of water channels up to 25 kilometers wide, and further downstream the Bangweulu Wetlands become one of the largest seasonal swamps on the continent. From the window seat on a flight from Lusaka to Dar es Salaam, the Chambeshi is the most visible feature for hundreds of kilometers in April and May - a landscape so saturated with water that the horizon disappears into haze and reflection. By August it is a river again, running dryly along its main channel, waiting for the next rain.