Behaviors of soil loss in slope-lysimeter, 3: Seasonal characteristics of erosion
1991
Nagasawa, T. (Hokkaido Univ., Sapporo (Japan). Faculty of Agriculture) | Umeda, Y. | Li, L.
Soil losses caused by rainfall and snowmelt were observed by the use of the slope lysimeter in December, 1988, to November, 1989. The seasonal or annual characteristics of the relation between soil loss and rainfall as well as between the rainfall-runoff and soil erodibility factors estimated by USLE were discussed. The results may be summarized as follows: 1) The quantity of soil loss caused by erosive rainfalls amounts to 92% of the total loss, whereas 99% of the total loss occurred at rainfalls with over 3 mm/hr peak intensity. 2) The rainfall-runoff factor, R, and soil erodibility factor, K, were estimated by USLE at 155.27 centiare.tf/ha and 6.62 x 10(-2)hr.t/centiare.tf, respectively, for erosive rainfalls. The value of R was 7% smaller than that from all rainfalls with soil loss, and, inversely, the value of K was 7% larger. 3) The quantity of soil loss increased in the order of spring, summer and autumn, and the amount of rainfall was also the largest in autumn. 4) The investigation of the K value indicated that soil erodibility varied seasonally. The value was the largest in autumn owing to the fact that the surface soil layer contains a large amount of water in this season
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