Measuring Vertical Distribution and Dynamic Development of Sediment Infiltration under Laboratory Conditions

The complex process of sediment infiltration in gravel beds has been studied widely. However, the temporal behavior of sediment infiltration and its clogging has not yet been investigated sufficiently. To understand the mechanisms involved in this phenomenon, measurements of the effects of various boundary conditions are required with high spatial and temporal resolution. The nonintrusive and undisturbed gamma-ray attenuation method was applied in this study to establish a measuring scheme to detect the dynamic development of river bed clogging and to investigate the effects of fine sediments’ particle-size distributions, total supplied mass, and supply rate on the sediment infiltration process. In a series of experiments, vertical profiles of infiltrated sediment masses were measured at two instants during the experiments. Then the dynamic changes of the infiltrated sediments at a specific position of the bed were investigated using continuous measurements during the experiments. The results of the measured vertical profile showed that sediment infiltration and clogging in an artificial bed matched the sediment’s existing bridging criterion of the porous gravel bed. Furthermore, temporal changes occurred mainly in the upper layers. The continuous one-point measurements indicated almost real-time sediment accumulation development and proved that higher supply rates lead to an earlier start of the infiltration and rapid filling, whereas lower supply rates result in later and slower infiltration of the sediments.