Watch “Why Do Rivers Curve?”

The St. Croix’s course is created by little disturbances, lots of time – and some interesting math.




< 1 minute read

The St. Croix would be a little boring if it went in a straight line. Imagine a big ditch. Fortunately, like all rivers, it has curves. The bends keep it interesting, constantly revealing new scenery. The short video below, published recently by MinuteEarth, explains why that is.

What we know today as the St. Croix’s course is fleeting and temporary in the long run. Based on sediment samples taken in backwaters on the lower river, those channels are only a few hundred years old. Anyone who explores the river knows its sandbars and banks shift frequently.

The video includes a segment on what Americans call Oxbow Lakes – the curves cut off as the channel shifts – and the many names for them used around the world. A YouTube commenter added that the Dutch word is Hoefijzermeer, literally translated as “Hoof-iron-lake” (or horseshoe).

Boaters and paddlers can learn one important piece of information for navigation in low water from the video: when in doubt, head for the outside of a curve, where the water is usually faster and deeper.

Bringing together nature and math, the video describes how the length of a river’s curve are generally six times its width. This could be a fun topic for local math and science teachers to bring into the classroom.

Watch the video:


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Watch “Why Do Rivers Curve?”