An experimental study of rill erosion and morphology

• Effects of rainfall intensity on rill network development were examined.
• Some indicators were presented for a quantitative description of rill morphology.
• Most rill inclination angle values concentrated between 15 and 25°.
• Degree of rill dissection was a better indicator to study rill erosion.

Rill erosion is recognized as an important process of water erosion on agricultural land. The objectives of this study are to examine the effects of rainfall intensity on rill network development and to present some indicators for a quantitative description of rill morphology. A soil pan (10 m long, 3 m wide and 0.5 m deep and with an adjustable slope gradient from 0 to 30°) was subjected to three successive rains under rainfall intensities of 50 and 100 mm h− 1. The results showed that rainfall intensity significantly affected rill erosion, especially in the active period of rill network development. The magnitude of rill erosion was 28.5 and 33.1 kg m− 2 and contributed 78.6% and 76.2% to the soil loss under rainfall intensities of 50 and 100 mm h− 1, respectively. The formation of rill network under the 50 mm h− 1 intensity was more complex than that under the 100 mm h− 1 intensity; for the latter rill networks developed fast and then varied slightly. The mean rill inclination angle (δmean), rill density (ρ), degree of rill dissection (μ) and mean rill tortuosity complexity (cmean) increased with the increase of rains under the same rainfall intensity. The μ value was the optimal derivative morphological indicator to estimate rill erosion and morphology, which was followed in descending order by δmean, cmean and ρ.