Abstract

This research aims at assessing and estimating soil erodibility factors influencing gullies in Anambra and Imo States, southeastern Nigeria. The Revised Universal Soil Loss Equation (RUSLE) parameters were determined using a separate equation, whose input was obtained from satellite imagery and Digital Elevation Model (DEM). Equations for calculating the variables were iteratively reviewed and the best equations were selected based on their suitability for use with the available data and their ability to provide estimates comparable to the reported field-based erosion measurements. Results revealed that, for Anambra State, the numerical range for areas classified as low erosion classes was between 11.23 and 47.71 and it indicated a total of 2216.93 tons of soil loss per year (46.57%). The areas classified as high erosion recorded a numerical range of between 97.32 (t/ha/year) and 157.12 (t/ha/year) which indicated an annual loss of 756.48 (t/year) (15.89%). The very high and severe erosion classes have numerical range values between 157.13 (t/ha/year) and 244.65 (t/ha/year) and between 244.66 (t/ ha/year) and 383.24 (t/ha/year) respectively. These two classes recorded annual loss of 378.86 (t/year) and 171.67 (t/year) respectively. The results of the % annual soil loss analysis computed for Imo state differs from the results observed in Anambra State. Imo State is experiencing a rather dynamic change with the low and moderate erosion classes areas recording higher amount of mean annual soil loss of 1169.99 (t/year) and 1043.17 (t/year) respectively. It is important to put in place good conservation management systems and good crop management systems to help reduce soil erodibility and thereby prevent soil erosion and soil loss. Similarly, knowing the predicted annual erosion rate is very important as this information will be useful for the improvement of conservation practices that will reduce rate of soil erosion thereby reducing soil loss in the study area.

Keywords:Soil erosion; Erodibility; Erosivity; Soil loss; Slope rate; Soil resource; Conservation