SOIL-EROSION PROCESSES IN SLOPING LAND IN THE EAST-COAST OF PENINSULAR MALAYSIA

Understanding soil erosion processes is essential in appreciating the extent and causes of soil erosion and in planning soil conservation. A comprehensive study was conducted on steep slopes on the east coast o f Peninsular Malaysia where the rainfall pattern is monsoonal. Rates o f rainfall and runoff, and soil loss, were accurately measured from fo ur large plots of 1000 m(2) and a bare plot of 20 m(2). Instruments us ed include Parshall flumes, height recorders, a pluviometer and a runo ff tipping bucket recording on a datalogger, with the associated compu ter hardware and software for data processing and analysis. Because of the slope of the land (about 18%) and the existence of large well-def ined flow pathways, soil was largely eroded through the processes of e ntrainment and reentrainment. Soil loss and runoff were particularly h igh where the pathways were very pronounced. Other factors influencing soil erosion were disturbance to the soil surface, which produced eas ily entrainable material, and percent contact cover. The parameter bet a, calculated for a large number of events, was found to vary accordin g to the availability of entrainable material, There was a gradual gen eral decrease of beta with time although most values were in the range 0.37 to 0.25, Suspended load was commonly more than 50% of total soil loss. Consequently, high chemical enrichment ratios were obtained. Th is has important implications on the reduction of soil quality through nutrient and organic matter losses.