Soil erosion and deposition rates in a cultivated catchment area in central Greece, estimated using the [formula omitted] technique

Abstract

The spatial variation of soil erosion and deposition rates was studied in a small catchment cultivated by rainfed agriculture, in the Mouriki area, Viotia Greece, using the 137 Cs technique. A 25 m grid was established parallel to the slope and the 137 Cs inventories were defined for the grid points. After establishing the local reference inventory, the soil erosion and deposition rates were estimated using the 137 Cs residuals for individual points on the grid in conjunction with the four conversion (calibration) models described by Walling and He (2001) [Models for converting 137 Cs measurements to estimates of soils redistribution rates on cultivated and uncultivated soils]. The conversion models were validated by means of sensitivity analysis and using local experimental data. The resulting estimates of soil redistribution rates were interpolated by means of kriging, using Surfer Golden software. The magnitude of the soil erosion rates depend on many factors, including the location of the sampling point, the local slope, and the soil properties. The mass balance model 2 (MBM2) and mass balance model incorporating soil movement by tillage (MBM3) conversion models predict soil redistribution rates of the same order of magnitude as the experimental data and are able to take account of Chernobyl fallout. Predicted soil erosion rates for catchment grid varied from 6.71 to 85.55 t ha −1 per year using MBM2 and from 3.54 to 95.78 t ha −1 per year using MBM3. Deposition rates varied from 1.23 to 168.19 t ha −1 per year using MBM2 and from 3.24 to 189.18 t ha −1 per year using MBM3. High correlation was apparent between erosion/deposition rates (MBM2) and soil P ( P<0.001), soil K ( P<0.001), soil organic matter % ( P<0.05), point slope ( P<0.05), clay % ( P=0.053) and altitude ( P=0.057). The total soil losses from the catchment have been estimated at 18.34 t ha −1 per year using MBM2 and 22.12 t ha −1 per year using MBM3.