Understanding the erosion dynamics and recognizing sensitive times and places to erosion within the catchment are necessary for erosion control. The seasonal and spatial variability of soil erosion under different contrasting lithologic conditions was studied in Vartavan catchment of Qazvin province of Iran. For this purpose, sediment trappers and erosion pins were placed in each parent material unit and were monitored at the end of each season. The results showed that the erosion rate of Vartavan catchment has large variations spatially and temporally. Based on the average weight of sediments in trappers, soil erosion rate is reduced correspondingly in units of light tuff (178.2g), black shale (34.4 g), red mudstone (29.9 g), andesite (21.7 g), dark tuff (16.7 g), sandstone (14.9 g), red sandstone (9.8 g), shale limestone (9.5 g), and eventually orbitolina limestone (6.5 g). The seasonal variation of erosion revealed that autumn has the maximum rate of erosion (71 %) which then decreases during the spring (19 %) and winter (10 %) until it reaches the minimum rate in summer. Understanding seasonal variations and identifying the critical months when the most amount of erosion occurs are essential for outlining soil conservation plans in specific lithological units.

Keywords