تغييرات زماني و مكاني هدررفت خاك تحت باران طبيعي در شمال غرب ايران

Temporal and Spatial Variations of Soil Loss Under Natural Rainfall in the North West of Iran

This study was conducted to investigate the temporal and spatial variations of soil loss in dry-farming lands in Hashtroud located in the north west of Iran. Soil loss was measured at the standard plots (1.83mx22.ini) in 36 dry-farming lands under natural rainfall events from March 2005 to March 2007. Based on the results, soil loss was significantly affected by the rainfall erosivity index, EI30 (R2- 0.88, p< 0.001). The rainfall erosivity and soil loss had the highest values during April with a 45.1 % and 52.7 % of their annual values, respectively. Spatial variation of the soil loss in April was similar to that one in the annual scale. It was simulated as spherical model with an effective range of 2.42 km. The highest value of soil loss was found in the northwest of the study area. Thus, controlling soil loss in the northwest of the area in April can be affective in decreasing annual soil loss. The results reveal that estimation of the soil loss in month scales and determination of its spatial distributions can be successfully used to control erosion in susceptible areas at a critical time.