Experimental investigation of freeze-thaw meltwater compound erosion and runoff energy consumption on loessal slopes

Abstract

The processes of rill erosion and overland flow are significantly affected by freeze-thaw cycles. Meltwater concentrated flow laboratory experiments were carried out to assess the soil erosion of different frozen conditions based on the runoff energy consumption process which own to runoff energy against the sediment transportation and terrain evolution. The experiments were performed over frozen, shallow-thawed, and unfrozen soil-filled flumes under 1, 2, and 4 L/min flow rates with the temperature around 5 °C. The results imply that soil erosion became more severe with increasing flow rate. Variation rate of the soil erosion rate of frozen slope was highest under 1 and 2 L/min flow rates due to lower infiltration of water into soil. Variation in runoff energy consumption variation with flow time presented significant differences under unfrozen, shallow-thawed, and frozen slopes at equal runoff rate (p < 0.05). Compared with shallow-thawed and unfrozen slopes, frozen slope displayed the highest runoff energy consumption and sediment yield capacity at the equal flow rate. Sediment yield capacity was constant regardless of soil condition except in shallow-thawed soil. The sediment yield capacity under 4 L/min flow rate was different from that under 1 and 2 L/min flow rates for shallow-thawed slopes. Soil erosion rates were predictable using runoff energy consumption under one soil condition. The results of this research would provide specific implications about meltwater erosion process and hydrodynamic conditions for improving the erosion model.