Our rivers might seem like permanent fixtures on the landscape, and in some cases form the borders of states and countries. The paths of some rivers are far from stable, and scientists from Swiss Federal Institute of Technology and Massachusetts Institute of Technology have developed a mapping technique that measures how much a river network is changing, and what direction is might be moving in.
How much a rivers path changes depends on the equilibrium between river catchments. Catchments are separated by a ridge line, or water divide. If the land surface or river channels on either side vary in steepness, the water in the river will erode the channel faster than the other, creating an imbalance. Over time the river will migrate, and hence the water divide will migrate, to ensure that both catchments are in balance.
The researchers found that by calculating these imbalances across divides they could predict the direction in which divides (and hence rivers) were moving through the landscape over time – and they tested this on locations in different parts of the globe.
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