The impact of natural polymer derivatives on sheet erosion on experimental loess hillslope

• The impact of natural polymer derivatives (NPD) on sheet erosion was tested.
• NPD can reduce runoff and erosion effectively.
• NPD can significantly improved the shear strength and the composition of surface aggregates of the soil.

Macromolecular polymers can effectively improve soil structure, increase soil penetration and control runoff and erosion on hillslopes. Simulated rainfall experiments on a bare soil investigated the impact of natural polymer derivatives (NPD) on soil properties and the characteristics of runoff and sediment yield of sheet erosion on experimental loessial hillslopes. A control (without NPD) and three concentrations of polymers (1, 3 and 5 g/m2) were tested at rainfall intensities of 1, 1.5 and 2 mm/min and a slope gradient of 15°. NPD effectively altered the onset, volume and sediment content of the runoff. Higher concentrations of NPD provided earlier onsets, lower depth and lower sediment contents of the runoff. Compared with control, cumulative runoffs decreased by 49–68%, 61–70% and 69–79% at concentrations of 1, 3 and 5 g/m2 NPD, respectively, while cumulative erosion modulus decreased by 31–37%, 39–47%, 56–61%, respectively. Additionally, NPDs significantly increased the shear strength and the composition of aggregates from soil surface. Shear strength was 2.71, 3.24 and 4.01 times higher at 1, 3 and 5 g/m2, respectively, than in the controls. The percent mass of aggregates >0.25 mm increased to 52.5%, 62.65% and 73.0% from 8.9% in the control at the three respective concentrations. More research is needed to confirm the utility of NPDs in helping to control sheet erosion.