Determination of soil loss by 137Cs fallout radionuclide in Omerli watershed of İstanbul, Turkey

Soil erosion and sedimentation in watersheds are usually part of the information to be considered for soil andwater conservation measures. Soil loss is generally estimated with models or measured with plot studies. Although falloutradionuclides (FRN)# methodology provides a powerful technique for predicting the impacts of proposed landmanagement strategies on soil erosion and sediment yield within river basins and estimates erosion based on falloutradioisotopes (Cs-137, Pb-210, Be-7) radioactivity, it is rarely used in Turkey. The aim of this study was to determine soillosses from different land use types with FRN’s methodology by using caesium-137 radionuclide in selected study sitesaround Pasakoy (shrub) and Esenceli (rangeland) villages in the environs of Omerli watershed. Bulk and 2 cm-depthincremental soil core samples were collected from the reference and sloping areas in both study sites. Soil lossesvaried from 0.49 to 23.22 t ha-1 yr-1 for shrub-covered sites and from 0.44 to 7.23 t ha-1 yr-1 for rangelands. The data showthat soil loss from shrub-covered site was greater than acceptable tolerance limit (10 t ha-1 yr-1) for soils of the sites.