Rainfall Induced Erosion Assessment on Hill Slope of GCE

Abstract

This study investigates the effect of northeast monsoon season rainfall to erosion on the hillslope of the Guthrie corridor expressway (GCE), Malaysia. The main focus of this study is to develop a relationship among the vegetation cover, slope steepness, and soil loss. A plot scale basis study area is established on hillslope along the GCE. To account for various vegetation densities, a number of five plots are proposed with various percentage of vegetation density. Experimental equipment is set up at those plots to allow collection of rainfall and soil loss for duration of five months, i.e. from November 2014 till March 2015, with twice collection per month. Based on the collected data, the effect of vegetation associated to soil loss is examined followed by propose of a new model. There are few points to summarize based on this study; 1) the observed rainfall pattern shows that mostly the recorded rainfall depth is about 5 mm with 20 minutes duration of rainfall; 2) plot without vegetation cover (i.e. NBNM) yields greater soil loss and with maximum runoff whereas the least is exhibited by the plot having natural dense microbe (NDM). Meanwhile, the planted vegetation is found affected the rate of soil loss; 3) a positive relationship is found between runoff and slope steepness regardless of the vegetation cover type; and 4) A newly proposed model reveals that higher Fvs value implies a low density of vegetation; hence contributes to more soil loss.