The Okavango

—square kilometres

—km of channel

—of it on flat sand

Down from the highlands

A channel, by how much country is above it

——

and the same channel on ground with no shape

Relief here is the range of the elevation model inside a 1.5 km block. Under ten metres of it and the land is Kalahari sand: the channel drawn across it is where the algorithm had to send the water, not a bed anyone has seen carry any.

The divide

the part of it crossing flat sand

the delta below it, from Landsat

The twelve systems

Whose country it falls on

Mark the stretches of the divide that cross flat sand Dim everything outside the lit basin