EROSION MODELING AT THE RMIL WATERSHED IN NORTHERN TUNISIA USING THE USLE AND THE SWAT MODELS

The objective of the research is to assess the soil erosion in the Rmil watershed using the SWAT and the USLE models.Laboratory analyses was conducted for determining texture and organic matter.The USLE model with light management like forest and agricultural practices represented by P factor indicated that about 28 % of soil loss rate in the Rmil watershed was between 5 and 10 t. ha -1 .y -1 .The soil loss rate more 10 t. ha -1 .y -1 represented over 12 %.The annual average soil loss arte is 5.12 t. ha -1 .y -1 .The integration of erosion control measures, represented by the P factor, shows an average soil loss rate of 3.85 t ha -1 .y -1 .The calibration of the monthly runoff showed an acceptable performance.The simulated soil loss using SWAT model varied from 0 to more than 20 t. ha -1 .y -1 with an annual average of 6.18 t. ha -1 .y -1 .The USLE method is able to spatially resolve the soil loss rate at a pixel and determine the prone area.Globally, the two models give a comparable estimates value of annual average soil loss rate.These spatial soil loss rates can be considered by decision-makers for planning management strategies to reduce soil loss.