Tectonic control on drainage, you say? I give you the Okavango Delta in
Botswana.
originally drained into, before faulting and subsidence of the East
African Rift cut off the Okavango river, creating the world's largest
inland delta. A smaller delta to the north marks where another river has
also been cut off by a fault. In this case the river diverts along the
fault escarpment to join the Zambezi river system to the north;
eventually the Okavango river will be captured in a similar way. Both of
these rivers originally linked with the Limpopo river, so tectonics is
causing a major reorganisation of drainage across the whole of Southern
Africa. The flashearth image is here