Erosion rates of soils improved by chemical additives for protection against overland flow

Overland flow erosion is frequently observed for the volcanic ash sandy soil named as Shirasu located in south western Japan. This paper presents a primary study to predict the rate of soil loss by overflow erosion (E _r) and its relation with the peak compressive strength (q _u). Series of physical models tests were performed on different samples of Shirasu soils reinforced by chemical additives such as calcium hydroxide and calcium oxide. The primary results reinforced the need to account for spatial variability of parameters such as the degree of compaction, water content and particles grading to make realistic predictions of soil loss through erosion by overland flow. The influence of spatial trend in the mean behavior of the critical flow velocities and soil erodibility also is shown to have a significant impact on soil erosion.