Background Planting Elymus dahuricus and Artemisia ordosica plays an important role in controlling soil erosion on dump slopes in open-pit mining area. However, the influence of root systems of E. dahuricus and A. ordosica, as well as their mixed root systems, on the runoff and sediment yield characteristics of rill erosion on dump slopes in the Erdos mining area is still unclear.

Methods The field simulated scouring experiment was conducted to study the hydrodynamic characteristics of rill erosion and characteristics of runoff and sediment yield on the dump slope with different plant root types (fibrous root system of E. dahuricus, tap root system of A. ordosica, mixed root systems of E. dahuricus and A. ordosica).

Results The runoff velocity, drag coefficient, runoff shear force and runoff power of different plant root types on dump slopes showed different change trends with runoff scouring time. The fibrous root system of E. dahuricus and the tap root system of A. ordosica both reduced the runoff velocity, runoff shear force and runoff power, while the two plants had different effects on the drag coefficient. Specifically, the fibrous root system of E. dahuricus increased the drag coefficient on dump slopes, while the tap root system of A. ordosica is the opposite. The average runoff yield rate reached its minimum value on the test plot of the fibrous root system of E. dahuricus. The sediment yield rates of the test plots of different plant root types decreased compared with the CK, and the average sediment yield rate had decreased by 51.28% to 69.40%. The presence of the three plant root systems effectively reduced the soil detachment rate on dump slope, among which the maximum erosion reduction rate of the fibrous root system of E. dahuricus was as high as 71.1%. The critical runoff shear force and critical runoff power of the test plots of three plant root types were 0.04-1.28 N/m/s and 0.02-0.25 Pa, respectively, and the two critical values were ranked from largest to smallest in the fibrous root system plot, mixed root system of fibrous root system and tap root system, the taproot system plot, and the bare plot.

Conclusions The presence of three plant root systems changed the hydrodynamic characteristics during the rill erosion process on the dump slopes under runoff scouring conditions, effectively reduced the amount of soil erosion. Among them, the E. dahuricus with fibrous root system had the best effect of reducing erosion, while the effect of A. ordosica with tap root system and the mixed planting of E. dahuricus and A. ordosica with mixed root system on reducing erosion is relatively poor. The results can provide a theoretical basis for the prevention and control of soil erosion on the dump slopes in the Erdos mining area.