The rainfall-runoff-erosion relationship in hillsides and microwatersheds

Abstract

The rainfall-runoff-erosion process was evaluated for runoff plots with different management practices for row and cover crops, as well as for a hillside parcel with corn crops in andosol soil. The study was carried out in 2007 in the Villa Victoria watershed, in the Mexico Cutzamala System. During the study period, 168 rainy events were registered, only 14 of which generated surface runoff and soil erosion. The results showed that in land with a 30 percent slope, the average efficiency of runoff and soil erosion control was 40% for row crops in contour strips and 62% for cover crops. In these soils, erosion was highly correlated with runoff, effective rainfall, peak runoff, rainfall intensity and antecedent soil moisture; surface flow (runoff) was related with peak runoff and rainfall intensity, and; peak flow was highly correlated with rainfall intensity. Though 37% of the total runoff occurred in June and July, total soil loss from erosion was 68%. It is during this period that the land is worked and the crop canopy coverage is between 45 to 85%. The minimum requirements for the rainfall-runoff-soil erosion process to occur were rainfall depth of 4.2 mm, rainfall intensity of 8.69 mm/h and an antecedent soil moisture near field capacity (around 53% humidity).