Effectiveness of Palm and Simulated Geotextiles in Reducing Run-off and Inter-rill Erosion on Medium and Steep Slopes

Abstract

Palm-leaf geotextiles could be an effective and cheap soil conservation method with enormous global potential. However, there are very few data on the effectiveness of palm geotextiles in reducing soil erosion by water. This study investigates the effectiveness of two types of palm geotextiles and the effect of geotextile mesh size on infiltration, run-off and inter-rill erosion rate and soil surface roughness on a medium and steep slope. A well-defined protocol was developed to conduct laboratory experiments. Rainfall was simulated for 90 min with an intensity (I) of 45 and 67 mm h−1 on an inter-rill erosion plot, filled with an erodible sandy loam and having slope gradients (S) of 15 and 45%. Two palm-leaf geotextiles (Borassus aethiopum and Brazilian Buriti Palm) and three simulated geotextiles (polyethylene tarpaulin) with different mesh sizes (1 × 1, 5 × 5 and 12 × 12 cm) were tested on a simulated fine tilth. Calculated k values from the Horton infiltration equation ranged from 0.025 to 0.145 and decreased linearly on both slopes with geotextile cover. Geotextiles are more effective in reducing the run-off coefficient on a medium slope (15%) compared with that on a steep slope (45%), ranging from 76.4 to 17.9%. Mean b values from the mulch cover equation equalled 0.024 for a 15% slope and 0.045 for a 45% slope, indicating a higher effectiveness of geotextiles in reducing total inter-rill soil loss on gentler slopes compared with commonly used mulches. Erosion-induced soil surface roughness at the end of each experiment increased linearly with geotextile cover percentage and this increase was not significantly different between the two slope gradients. (Blackwell Publishing)