A STUDY OF SURFACE WASH AND RUNOFF AT TEKALA FOREST RESERVE MALAYSIA (Kajian Hakisan dan Aliran Permukaan di Hutan Simpan Tekala, Malaysia)

Abstract

The surface wash and runoff study was carried out using closed erosion plots in TekalaForest Reserve in Hulu Langat, Selangor. Variation on the rate of surface wash andrunoff were analysed for different slope gradient and at varying physical and chemicalsoil characteristic. It was found that silt and fine sand were subjected to higher erosionrate compared to clay and course sand. Content of fine sand and silt in eroded materialsincreased in the range of 4.8 to 7.0 % and 11.8 to 22.5% respectively. The averagereduction of course sand and clay were 8.6% and 16.0% respectively. The average rate ofsurface wash at study site were 85.0 g m-2 yr-1 . This was relatively higher compared tosoil loss in Sarawak of 35.5 g m-2 yr-1 . There was a significant and positive correlationbetween rates of surface wash and surface runoff with average product momentcorrelation, r of 0.75. During the study period, seven extreme events with rainfall greaterthan 50 mm in single storm were recorded. These storms account for 25% of the totalrainfall and 29% of the surface wash during the one year study period between 7th August1994 to 17th August 1995. There were also positive and significant correlation betweenslope angle and surface wash (0.92) and the surface runoff (0.77).