First use of the 7Be radionuclide for estimating soil redistribution rates on dry farming land in Kermanshah Province

Over the past decades, the fallout radionuclides 137Cs, 210Pbex and 7Be are increasingly being used to quantify soil erosion and sedimentation rates. Although studies using 137Cs and to some extent 210Pbex are now well-documented, there is a need for further work aimed at exploring the use of 7Be, particularly in arid and semi-arid areas. Investigating soil erosion processes occurring over shorter timescales, particularly individual storm events or short periods of heavy rainfall is the major advantages of recently developed 7Be method over the assessments of longer-term erosion rates provided by 137Cs or 210Pbex. The present investigation is the first investigation of using 7Be techniques in Iran. A hillslope with dry farming land use, in south west of Kermanshah, with a mean annual rainfall of about 480 mm, was selected. Soil sampling performed in April 2011, after occurring 150 mm rainfall in 40 days. The net erosion rate was estimated to be 6.8t ha-1 yr-1 by using Profile Distribution model. According to the short period, the high net soil erosion rate is most likely the result of the mismanagement of the field, cultivation operation along the main slope direction, the heavy rainfall occurring during the late winter and early spring seasons without major vegetative cover and the steep topography. The sediment delivery ratio was about 80% indicating that significant part of the mobilized soil was removed from field. The results confirm the potential of using 7Be measurements to document soil redistribution associated with short periods in semi-arid area.