Resumen de The effects of rainfall intensity and rock fragment cover on soil hydrological responses in Central Chile

Eduardo von Bennewitz, Jesús Aladro

• In Chile, 60% of the usable land is affected by erosion and the effects of rock fragment cover, however protecting the soil against these degradation processes have been sparsely studied. Understanding the effects of rainfall intensity and rock fragment cover on soil hydrological processes is a major challenge for the formulation and implementation of proper soil conservation plans. The effects of rock fragment cover on soil erosion rate, surface runoff, sediment concentration and infiltration rate were studied on a Cambisol in Central Chile using the CAZALAC rainfall simulator. Nine rainfall simulations consisting of different combinations of rainfall intensities (70 mm h-1, 90 mm h-1, and 120 mm h-1) and rock fragment cover (0%, 40%, and 70%) were carried out. Rock fragment cover contributed to delay the time to start surface runoff and the amount surface runoff was in most of the cases directly proportional to rainfall intensity and inversely proportional to rock fragment cover percentage. Rock fragment cover reduced surface runoff in up to 72.06% in the case of the highest rainfall intensity. Final infiltration rate increased directly proportional to the percentage of rock fragment cover for each of the studied rainfall intensities. Erosion rate tended to be reduced by rock fragments (82.2% of reduction in the case of the highest rainfall intensity and rock fragment cover), but this positive effects were not always proportional to rock fragment cover percentage. In general, lower sediment concentrations were found in covered soils (more than a tenfold reduction in the case of 120 mm h-1 rainfall intensity).