Aug. 21, 2015 -- New research from a recent study conducted by Dr. Yun Ding of Hohai University in China -- in collaboration with partnering entities -- has found an innovative and efficient approach to study the complicated mechanism of water pollution in alluvial rivers.
The present work investigates the dynamics of the active bed layer and simulates the pollution process due to resuspension of bed materials absorbing pollutants. A transport equation of the active bed layer was established to describe the dynamic characteristics of the temporal and spatial variation of pollutants absorbed to bed materials, and it quantitatively reflects the effects of the evolution of the layer on the pollution process.
In alluvial rivers, the pollution process not only takes place in the sediment-laden flows, but involves the riverbed evolution. The coupled interaction between flow movement, sediment transport and riverbed evolution induces the variable distribution of sediment particles, thereby resulting in the complex mechanism of pollutants transport.
Particularly, resuspension of sediment particles from bed materials absorbing pollutants potentially poses unpredictable challenges to the prevention and forecast of pollution, and its mechanism has not been widely recognized. Therefore, study of the water pollution due to resuspension of bed materials is of scientific and practical significance. However, the search of the literature reveals no dynamic description of pollutants transport in the active bed layer.
"To the best of our knowledge, most previous studies generally adopted critical conditions to determine the fluxes exchange between the waterbody and riverbed, and the dynamic of pollutant transport in the active bed layer could not be illustrated," the researchers explained. "This work represents the physical nature of pollutant transport in alluvial rivers."
A coupled mathematical model in which the transport equation of the active bed layer is taken account into is established to study water pollution in the alluvial rivers. Compared to previous researches, the complicated coupling mechanism between water motion and evolution of river bed is innovatively described by the physical based transport equation of the active bed layer. Research results are in good agreement with the experimental observations.
The present work enriches approaches to study the environmental effect in the nature system. Further, it provides an effective tool for the water safety and river management.
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