PAST LAND-USE ACTIVITIES IN RELATION TO THE LONG-TERM SUSPENDED SEDIMENT YIELD OF KINTA RIVER, PERAK, MALAYSIAM. HASHIM AND W. R. ISMAIL
Soil erosion and the suspended sediment yield (SSY) of Kinta river catchment were investigated using river and sediment discharge data of Kinta River and its tributaries available from 1961-2006. A long-term annual SSY for the Kinta River basin recorded an average of 2417.6 t/km2/year, with a maximum SSY of 8,757.3 t/km2/year in 1973 and a minimum SSY of 720.4 t/km2/year in 2005. The Mann-Kendall test was conducted to analyse the long-term SSY trends, which revealed an overall decreasing trend of SSY for the Kinta River basin. This 46-year period was divided into four phases of different SSY trend. The second phase from 1970â1985 recorded the highest average of 4,062 t/km2/year, as a result of the rapid development process that occurred in the drainage basin. The declining trends in SSY were observed after many mining operations ceased after 1960 and dam construction start in 2003. Some increasing trends in the early 1970s to 80s were due largely to the initial implementation of the New Economic Policy (NEP) and Green Book Plan. It involved a large-scale conversion of forest areas into agricultural lands with the expansion of urban areas and improvement of infrastructures.