EPOW - Ecology Picture of the Week

Kasai River, Remote and Red

Kasai River, Kasai Province
Democratic Republic of the Congo

Explanation:  Into the remote heart of the Congo River Basin stretches this immense tributary of the Congo River.  This is the Kasai River that stretches and bends over 1300 miles (2100 km) from Angola into the Democratic Republic of the Congo.  

Here, the Kasai forms a striking contrast with the savannas and the patches and stringers of tropical woodlands, below.  Islands of dense forest punctuate the twisting river course, and only occasionally a village may be seen along its edge.  

What makes the Kasai unique among the many other vast Congo tributaries, however, is not its remoteness, but rather its redness.  Why is the Kasai so red?

I asked that question of my Congolese hosts and friends, but none had a satisfactory explanation other than perhaps it is a heavy sediment load that the river carries.  But why the Kasai appears so burnt orange while other rivers of the region do not, I haven't yet discovered.  

Nor how its apparent opacity might influence its ecology.  These rivers seem to all carry catfish and other bottom-dwelling species that can thrive in highly sedimented conditions.  But the Kasai seems to harbor a high biodiversity despite its apparent turbidity.

So as we ponder a bit of a mystery, enjoy the following comparisons between my own aerial photos (on the left) and matched images I found on Google Earth (on the right):

Although colors differ, both the "live" photo on the left and the Google Earth image
on the right present the same patterns of river, savanna, and woodlands.
(As usual in EPOW, click on any image for larger versions.)
 
  

Occasionally, riverside villages have grown up along the banks, 
depending on the fish bounty.  Notice the dirt roads providing 
the only connections with other villages, in the following photo:

As far as one can see, this remote interior of the Congo River Basin
stretches flat and largely uninhabited.
The rivers wind with broad bends, being nearly "at grade"
as the term is used to describe drainages in nearly flat landscapes.
The scene seems to define infinity itself.