SPATIAL VARIABILITY OF SOIL ERODIBILITY AT EL HAMMAM CATCHMENT, NORTHEAST OF ALGERIA

Abstract

The concept of erodibility has gained a great importance in the field of soil erosion modelling and applications of soil conservation. Soil erodibility factor has become one of the key factors which determine soil particles resistance to be detached by water erosion. This study was performed to determine soil erodibility factor and assess spatial variability of soil erodibility using geostatistics at El Hammam catchment. In this study 51 samples of surface soil (0-20cm) were collected across the study area of 1000 Ha by preparing point map at GIS. Sampling points were identified in field by a Global Positioning system. Some soil properties and organic matter were measured at laboratory, and permeability and structure were determined using soil texture analysis. Amount of soil erodibility changed from 0.16 to 0.66. The variability analysis has shown that soil properties and erodibility factor have varied significantly in cropland and have ranged from 63% in organic matter and 39% in K factor. The statistical analysis indicated negative correlations of erodibility with clay, organic matter and permeability and negative correlations of this factor with silt, sand and soil structure. Based on kriging interpolation method, soil erodibility factor map was generated using Ordinary Kriging. The spherical model has given the best model to predict spatial variability of soil erodibility which root-mean-square error and mean error values of interpolated map were very low. The range of the spatial dependency was equal to 460 m. The study basin has been classified as highly erodible and ecologically vulnerable.