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 Tekala
Forest Reserve in Hulu Langat, Selangor. Variation on the rate of surface wash and
runoff were analysed for different slope gradient and at varying physical and chemical
soil characteristic. It was found that silt and fine sand were subjected to higher erosion
rate compared to clay and course sand. Content of fine sand and silt in eroded materials
increased in the range of 4.8 to 7.0 % and 11.8 to 22.5% respectively. The average
reduction of course sand and clay were 8.6% and 16.0% respectively. The average rate of
surface wash at study site were 85.0 g m-2 yr-1 . This was relatively higher compared to
soil loss in Sarawak of 35.5 g m-2 yr-1 . There was a significant and positive correlation
between rates of surface wash and surface runoff with average product moment
correlation, r of 0.75. During the study period, seven extreme events with rainfall greater
than 50 mm in single storm were recorded. These storms account for 25% of the total
rainfall and 29% of the surface wash during the one year study period between 7th August
1994 to 17th August 1995. There were also positive and significant correlation between
slope angle and surface wash (0.92) and the surface runoff (0.77).