Abstract:Sediment in water is the essential difference between the irrigation of muddy and clean water. The one-dimensional vertical infiltration experiment with muddy and clean water was conducted to reveal the influence of sediment concentration in muddy water on one-dimensional vertical infiltration characteristics and dense layer formation. Four sediment concentrations (3%, 6%, 9%, 12%) were set up to study the effects of sediment concentration on one-dimensional vertical infiltration capacity, wetting front movement distance, soil particle composition in dense layer and the thickness of deposition layer. The models of cumulative infiltration and the wet front movement distance with sediment concentration in muddy water and infiltration duration as independent variables were proposed respectively, and the relationship between the thickness of deposition layer and the infiltration duration of one-dimensional vertical infiltration of muddy water with different sediment concentrations were established. The results showed that the increase of sediment concentration in muddy water, the cumulative infiltration, the infiltration rate and the movement distance of wetting front of muddy water all decreased, while the thickness of deposition layer increased. The thickness of the deposition layer was small at the initial stage of infiltration (0-20 min), increased rapidly in the middle stage of infiltration (20-130 min) but the increasing rate gradually decreased, and increased steadily in the late infiltration stage. With the increases of sediment concentration in muddy water, the sediment retention became more obvious, so the fine particles decreased while the coarse particles increased in the deposition layer. The fine particles increased in the stranded layer with the increase of sediment concentration, and the physical clay particles was significantly higher than that of the original soil, especially at 0-1 cm infiltration depth.