Assessment of bed clogging in surface water reservoirs under different hydrologic conditions

Physical clogging of porous media plays an important role in controlling their hydraulic conductivity. This study investigates how uniformly graded medium-to-coarse sand in a reservoir's bed performs in response to the inflow of turbid water with fine suspended sediments. Different particle sizes, heads, and concentrations were simulated to cover a range of hydrologic conditions. A 1D sand column was used with three bed material sizes and three suspended particle sizes. Seven particle size ratios were tested under a constant head. Four heads and three suspended sediment concentrations are also evaluated. It was concluded that the decline in the relative hydraulic conductivity of the bed material is directly proportional to the ratio of sediments-to-bed particle sizes. Increasing the concentration of suspended sediments accelerated the rate of clogging, while bigger heads increased the depth of clogging. The study highlights how physical clogging affects the water balance in surface reservoirs and threatens the safety of dams.