Water flow velocity over frozen and nonfrozen black soil slopes

摘要

Ice- and snow-melted water flow over partially thawed frozen soil of cultivated slopes causes serious soil erosion, which results in soil degradation and affects productivity in Northeast China. Water flow velocity over frozen and nonfrozen soil shows importance in understanding meltwater erosion. In this work, a series of laboratory experiments were conducted to measure water flow velocity over frozen and nonfrozen soil slopes. Experiments were performed using the electrolyte trace method under the pulse boundary model, under conditions of 4 slope gradients (5 degrees, 10 degrees, 15 degrees, and 20 degrees), 3 flow rates (1, 2, and 4L/min), and 7 sensors positioned at 0.1, 1.0, 2.0, 3.0, 4.0, 5.0, and 6.0m away from the electrolyte injection point. Results showed that velocities over frozen soil slopes increased with flow rate and slope gradient. Flow velocities over nonfrozen soil slopes increased with flow rate and slope gradients from 5 degrees to 15 degrees and stabilized at 15 degrees. Flow velocities over frozen soil slopes were 30%, 54%, 71%, and 91% higher than those over nonfrozen ones at slope gradients of 5 degrees, 10 degrees, 15 degrees, and 20 degrees. Flow velocities over frozen soil slopes under different flow rates of 1, 2, and 4L/min were approximately 52%, 59%, and 79% higher than those over nonfrozen soil, respectively. This study can help in assessing the erosion of partially thawed frozen soil by meltwater flow.