Assessment of rainfall-induced soil erosion on hillslope: a case study at the Guthrie Corridor Expressway, Malaysia

The effect of northeast monsoon rainfall to soil erosion on hillslope adjacent the Guthrie Corridor Expressway, Malaysia, is investigated by examining a relationship between vegetation covers and slope steepness. Five plot-scale study areas [i.e., NBNM, PDM, PDNM, NBM and natural dense microbe (NDM)] are marked on the hillslope with different percentage and type of vegetation densities. Experimental equipment is set up at those plots to collect rainwater and soil loss starting from November 2014 until March 2015 with twice collection per month. Based on the data collected, the effect of different vegetation densities associated to soil loss is examined. These are the conclusions that can be made based on this investigation: (1) the observed rainfall pattern shows that mostly the recorded rainfall depth is about 5 mm with 20 min duration of rainfall; (2) plot without vegetation cover (i.e., NBNM) yields greater soil loss with the maximum runoff, whereas the least is exhibited by the plot having NDM. Meanwhile, the rate of soil loss is found greater for the planted vegetation compared to the natural plant; (3) a positive relationship is found between runoff and slope steepness regardless of the vegetation cover types.