Influence of hydraulic gradient and temperature on the migration of E. coli in saturated porous media during bank filtration: a case study at the Second Songhua River, Songyuan, Northeastern China

River bank filtration can effectively reduce the number of pathogenic microorganisms infiltrating into groundwater from surface water. Groundwater seepage velocity and temperature are considered to be important factors affecting the process, but the magnitude and mechanism of their impacts have not been clear for a long time. Based on the actual monitoring data of the Escherichia coli concentrations and soil samples of Second Songhua riverside...