Analysis of Risk Factors for Erosion and Runoff in the Isser Catchment

Abstract

Water erosion and runoff are important contributors to soil degradation in the semi-arid Isser catchment of north-western Algeria. The area is characterised by irregular rainfall events of short duration and generally high intensity, with the manuscript reporting a maximum rainfall intensity of 80 mm/h in 25 minutes. This study assessed the risk factors associated with erosion and runoff by examining surface conditions, infiltration behaviour and selected physicochemical properties of soils from the Madjouj and Sidi Ahmed Cherif sites. Field observations and laboratory analyses considered surface cover, cracks, pebbles, plant debris, infiltration under wet and dry conditions, particle size distribution, structural stability, bulk density, moisture, permeability, pH, electrical conductivity, colour, organic matter, total nitrogen and total limestone. The results indicate that the soils are mainly silty-clay to clayey, with marly characteristics and generally good bulk density. Although the soils show some resistance to splash erosion, runoff may begin rapidly after rainfall, particularly where clay swelling, weak vegetation cover and unsuitable land management reduce infiltration. Fallow plots showed higher organic matter and better aggregate stability than ploughed plots, suggesting that soil cover and reduced disturbance can improve soil fertility potential. The study supports the need for locally adapted water and soil conservation practices that consider both soil properties and the socio-economic needs of the local population.