Beneficial effect of palm geotextiles on inter-rill erosion in South African soils and mine dam tailings : a rainfall simulator study

Abstract

Geotextiles are reported to be highly effective and economically viable erosion control products. The objective of this study was to test this hypothesis by determining the extent of differences in erosion-related variables between bare soils and mine tailings and those covered with palm mats, via rainfall simulation. Erosion parameters studied included runoff (RO), sediment load in the runoff (SL), percentage of stable aggregates (SA), final infiltration rate (FI) and inter-rill erodibility (Ki). Thirty samples, representative of South African soils and mine tailings, were investigated. The soils varied considerably with respect to their textural, chemical and mineralogical properties in line with soil taxonomy, annual precipitation and geological substrate. Tailing sample selection was based on the dominant type of mine. Erosion parameters varied greatly within, but to a much lower extent between, the two different types of material. Several significant correlations were obtained. Sediment load had the best correlation with kaolinite content and with fine sand content, while for runoff, the best correlation was with organic carbon content. When the samples were covered with palm mats, final infiltration rate, stable aggregate and inter-rill erodibility values were similar to those of bare materials and the amount of runoff was slightly higher. Sediment load, however, was reduced by 65%. These results document the suitability of palm geotextiles for soil conservation.