WATER YIELD CHANGES AFTER FOREST CONVERSION TO AGRICULTURAL LANDUSE IN PENINSULAR MALAYSIA

Abstract

A paired-watershed experiment, comprising three small catchments in Sungai Tekam, Pahang, Peninsular Malaysia, was carried out from 1977 to 1986 to determine and quantify the effect on water yield of a typical forest land conversion to agricultural landuse. Two Catchments, A and B, were treated after five and three years of calibration and subsequently planted with cocoa and oil palm, respectively. Significant increases in water yield were observed in both catchments. The highest increase occurred in the second and fourth year after treatment, amounting to 706 mm (157%) and 822 mm (470%) in Catchments A and B, respectively. Different magnitudes of annual yield increment apparently reflected the various activities of land conversion including timber harvesting, under-brushing, clear felling, road construction and planting of cover crops. Management implications of these yield increases are discussed.