THE LIFEBLOOD OF THE LANDSCAPE
Just two rivers originating in southern Angola supply nearly all the water that flows into Botswana’s Okavango Delta. Protecting them is the key to preserving the richness of life in this unique place.
From the modest elevation of the Angolan highlands (top left of the animated map above), water has basically two ways down: rushing steeply down the western side, or sliding gently along the gradual lowering of the plateau to the south and east.
When the annual rains come (illustrated by increased plant growth, shown in green) in the steep, rocky west they rush quickly down waterfalls, form deep channels, and feed the seasonal floods of the Cubango River. This drives the dramatic seasonal expansion of life in the Okavango Delta (the fan-shaped bloom of green in the center).
After building up for weeks, water eventually bursts forth from the southern part of the delta, forming the Boteti River, and flows out to the Makgadikgadi Pans. These seasonal salt pans by that time have already turned to lakes, fed by floodwaters of the Zambezi to the northeast. (On the middle left of the map, note the similar salt pans that have no significant feeders and stay dry year-round.)
MAP REFLECTS SEASONALITY ACROSS THE REGION, BASED ON FIVE-YEAR AVERAGE PLANT GROWTH
In the eastern highlands though, without the steep terrain, forests absorb and retain the moisture of the rains, and feed peat beds around the source lakes of the Cuito River. Peat can hold 20 times its weight in water, allowing it to absorb the water of the short rainy season and slowly release it, making the Cuito more resilient during dry seasons. (This is why the eastern highlands never lose their green in the map). The dense organic content of the peat also filters the water, making its flow particularly pure and clean. This marks another contrast with the wild, mud-and-debris-filled flood waters of the Cubango.
Both rivers are essential to the future of the delta, but they face different pressures. The Cubango is stressed from existing development and poor management. The Cuito remains isolated and pristine, but is threatened by the potential of unregulated development and the erosion and ecological change caused by extensive human-set fires. Protecting the Cuito would help secure 45 percent of the delta’s water. Managing the Cubango more sustainably would help protect the rest.
WATER MAP BY MARTIN GAMACHE, ART OF THE MAPPABLE; SOURCE: USGS/FEWS NET (DATA SOURCE: NASA). PHOTOGRAPHS BY CHRIS BOYES (“WATER”), GÖTZ NEEF (“BIODIVERSITY”), KOSTADIN LUCHANSKY (“COMMUNITY”).