The Kander: The River That Flows Uphill

Two years ago, we wrote about the chameleon-like river on our doorstep: the Kander. Depending on the weather in Gasteretal and what kind of rock the Kanderfirn glacier has recently ground up, the river changes from brown to blue to green to colourless.

But I have noticed another peculiar thing about the Kander, it flows uphill. Not the whole river, but certain parts of it, and only in certain places. If you have visited us you must have seen one of those places, in the river bend underneath the bridge.

Figure 1: Point bar in the Kander

The little “beach” in the picture above, called a point bar, was a lot smaller half a year ago (And it was not because of higher water levels). Over the course of the summer underwater currents in the river deposited more and more sand and gravel in the inside of the river bend.

The way this works is that because of the water flow through the bend the water pressure in the outside of the bend is higher than on the inside of the bend. This difference causes water at the bottom of the river to flow from the outside to the inside of the bend, (uphill!) as shown in the sketch.

The way this works is that because of the water flow through the bend the water pressure in the outside of the bend is higher than on the inside of the bend. This difference causes water at the bottom of the river to flow from the outside to the inside of the bend, uphill (!), as shown in the sketch.

Figure 2: Secondary flow

As the water flows uphill, it moves sand, gravel and rocks across the river, creating the point bar. You can see this for yourself when you put a lot of sugar in your tea and start stirring it: the sugar moves to the middle of the cup.

This underwater current is called the secondary flow. It’s a funny coincidence that the first to describe this process was Albert Einstein. Okay, maybe that’s not so funny, but it’s small and slow processes like this that make rivers define or even create entire landscapes with their meanders, like the Argentinian Río Negro and U.S. Colorado River pictured below.

Stay tuned for more posts about the Kander in the near future!

Dries (NL)

 

Figure 3: Rio Negro, Argentina (all the curves are routes the river took in the past, sometimes leaving a lake behind)

 

Figure 4: Colorado River, U.S. (“locked” meanders; weird colours showing different geological layers)

Dries (NL)
Grounds Manager