Forest cover changes analysis using Landsat Imageries over Pengabuan Watershed in Jambi Province

Abstract

The availability of land cover in the form of forest is very important in the watershed system (DAS). The decrease in forest cover and the carbon content stored in a watershed also shows a decline in the quality of the watershed. The research aims to examine changes in land cover that occurred during the last twenty years in the Pengabuan Watershed. Changes in land cover were obtained by classifying Landsat imagery from 1996 to 2017. Classification was carried out using the supervised classification method and visual interpretation and then followed by change detection analysis. The result showed that from 1996 to 2017, secondary dryland forest cover and bare land in the Pengabuan watershed has been declining, the rate of secondary dryland forest decreased by 53.38% (11,186.47 ha / year), the rate of decline in bare land by 1, 26% (264.29 ha / year). Land cover with an increasing area such as settlements at 2.29% (479.24 ha / year), plantation forests at 17.31% (3,626.75 ha / year), dry land agriculture at 1.63% (341, 41 ha / year), plantations at 33.12% (6,940.13 ha / year) and water bodies at 0.30% (62.94 ha / year). Changes in land cover are caused by increased land requirements for various uses and implementation of government policies. Forest cover in Pengabuan Watershed in 2017 only covers 14.1% of the total area of the Pengabuan Watershed (419,114.49 ha). This shows that the minimum coverage of existing forest in this watershed area has not reached 30%. Changes in land use patterns are one factor in causing the decrease of carrying capacity of watersheds. Conversion of forest cover, especially forest areas into plantations, agriculture, bare land and others, has led DAS area vulnerable to the occurrence of floods, erosion, the threat of drought in the dry season, decreased water quality, land productivity and the threat of siltation of the estuary due to sedimentation.