Author(s): Zhoobin Rahimi, Faridah Othman
Linked Author(s): Zhoobin Rahimi
Keywords: Soil loss assessment, climate cycles, land use conversation, annual sediment, southern oscillation index
Abstract: Rainfall intensity and human activity accelerate soil erosions. According to the southern oscillation index (SOI), a La Nina period occurred during 1999. As a result, a series of heavy rainfall events were recorded over peninsular Malaysia. Meanwhile, a human activity such as mining and dam construction at this area has heavily changed the land cover during 1990s. Geographic information systems (GIS) and satellite images are two important tools that enable us to overlay these factors to observe the spatial distribution of erosion process. This study shows the effect of the heavy rainfalls of 1999 and human activities on soil loss and sedimentation at highlands of Fraser hill in Malaysia. In this study, we used a GIS-based universal soil loss erosion (USLE) model to study the spatial changes of land cover as a result of human activities. We generated two land cover maps using Landsat images in 1990 and 1999. The results of generated land cover products show that due to increasing construction and mining activities the forest area has decreased by 600 km2. As a result, the land cover maps show a significant increase of soil loss in 1999. Moreover, according to the collected data from Department of irrigation and drainage (DID), the accumulated annual sediment at the downstream of Fraser hill watershed significantly increases from 3. 2 tons per hectare per year in 1990 up to 7. 3 tons per hectare per year in 1999 while the average rainfall at these two occasions slightly increases by 3 mm. This results shows that land cover changes has a greater impact on sedimentation when compared with rainfall intensity. Finally, comparing the estimated annual sediment by USLE model with collected data shows 0. 3 ton per year bias which indicate that Landsat images can be an alternative source of data to map the geomorphological processes
Year: 2017