Assessment of soil erosion and sediment deposition in Songkla Lake Basin
2006
Chanchai Thanawut(Prince of Songkla University. Hat Yai Campus, Song Khla (Thailand). Faculty of Natural Resources) | Chao Yongchaloemchai(Prince of Songkla University. Hat Yai Campus, Song Khla (Thailand). Faculty of Natural Resources)
Present study assessed the amount of soil losses and sediment deposition in Songkla Lake Basin, Southern Thailand. Through the use of the Universal Soil Loss Equation (USLE) model in GIS environment, it was estimated that 22,951,339 tons of soil were lost from the basin in 2002, representing an average soil loss of 30.9 t/ha/y. Further analyses revealed that 324,020 hectares, or 43.6 percent of the basin's land area, were subjected to a very slight rate of soil erosion. The results also showed that 4.4 percent of the land area, equivalent to 32,809 hectares, was subjected to a severe rate of soil erosion. Most of the severely eroded land was found on the mountain terrain to the west and south of the basin. The total sediment discharged into the lake systems in 2002 was estimated to be 6,885,402 tons, an average of 813.6 t/square km of the basin, which would give a sedimentation rate of approximately 0.44 cm/y. As a substantial proportion of the lake sediments could pass through a narrow outlet on the south of Thale Sap Songkla to the sea, the actual rate of sedimentation in the lakes could be lower. Conservation-effective measures to control soil erosion are discussed.
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