Effect of bed permeability on how rivers flow

What is it about?

The permeability of a river bed has an important control on biologically-important hyporheic flow and the movement of pollutants into and out of the bed. However, relatively little is known about the effect of bed permeability on how rivers flow. We used laboratory experiments involving laser-based flow measurements to examine this effect. We have shown for the first time that flows over permeable beds exhibit fundamental differences compared with flows over impermeable beds of the same topography.

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Why is it important?

Our findings show that bed permeability is an important control on aspects of river flow that influence hyporheic exchange, fluvial sediment dynamics and benthic habitat availability. Therefore river flows, and the processes that occur within rivers are unlikely to be adequately predicted by numerical models that usually represent the bed as an impermeable boundary. As a consequence, our work shows that understanding more about surface–subsurface flow coupling represents an important research frontier for river scientists.

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