How grass contributes to controlling soil erosion

Abstract:

It is still unclear how grass restoration affects overland flow hydraulics and hillslope erosion. A series of experiments was conducted on grassland and its spatial distribution in hillslopes to probe into the mechanism of grass on soil erosion control. The experimental results show that in some mountain areas where land resources are limited, the grass strips are recommended to resort to or planted on the downslope or outlet of the watershed, rather than on the upland. The greater effectiveness of grass in controlling soil erosion is mainly attributed to the decreased rill erosion, and possibly trapped upslope inflow eroded sediment.

Under different overland flow or rainfall conditions, there should be differences in the relative importance of grass roots and above-ground parts in controlling erosion. Under rainfalls with low intensities (e.g., <60 mm h-1) grass roots can play an important role in reducing soil loss due to the improvement of soil anti-erodibility. While under heavy storms, the effectiveness of the above-ground parts of grass significantly strengthened due to the decreased overland flow scouring ability.

These results are beneficial to understand the dynamics of runoff and erosion on hillslopes impacted by vegetation restoration. Also, they are useful in conducting soil and water conservation in the local areas.