Water pollution has been a historical and stubborn problem in the water resource management. Several water pollution accidents continually occurred all over the world, threatening the safety of industry, agriculture and drinking water for resident's life (see Figure 1). An innovative and efficient approach was identified to study the complicated mechanism of water pollution in alluvial rivers.

The article titled "Numerical Simulation of Pollution Process Due to Resuspension of Bed Materials Adsorbing Pollutants in Alluvial Rivers" was recently published in Science China Technological Sciences, volume 58, 2015. The corresponding author is Dr. Yun Ding of Hohai University. The authors adopted the mathematical model to simulate the water pollution process in alluvial rivers.

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.

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 active bed layer on the pollution process.

"To the best of our knowledge, most previous studies generally adopted critical conditions to determine the fluxes exchange between the water body and riverbed, and the dynamic of pollutant transport in the active bed layer could not be illustrated" wrote the three researchers, "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. And it provides an effective tool for the water safety and river management.

Y. Ding, Y. Xiao, D. Zhong, "Numerical simulation of pollution process due to resuspension of bed materials adsorbing pollutants in alluvial rivers," Sci. China. Tech. Sci. (2015), 58(7): 1280-1288.doi: 10.1007/s11431-015-5845-9