First-of-their-kind river measurements show different flows over gravel, sand

New research in fluid dynamics reveals that water behaves differently as it flows over certain types of river bed substrate, according to a release from the University of Illinois at Urbana-Champaign.

Using an artificial flume constructed in the university’s labs, the researchers tested river bed substrates ranging from impermeable to totally permeable. The researchers also modified a technique known as particle image velocimetry to examine fluid flow that occurs between individual grains, such as gravel. Such measurements had never been established before.

With separate flow rates for the river bed and the stream above, the researchers’ findings proved vastly different than previous models, which focused on grain roughness rather than permeability. The research could contribute to models that predict how nutrients and pollutants move downstream.