Land Use Changes on the Slopes and the Implications for the Landslide Occurrences in Ujung-Loe Watersheds South Sulawesi Indonesia

Abstract

Ujung-Loe watershed located in South Sulawesi, Indonesia and there have many lands use change (LUC) and landslide occurrence. By use of unsupervised interpretation, the land use 2004 and 2011 has been interpreted and overlaid with a landslide (occurrence 2012 and above) to derivate factor of landslide due to LUC. For this purpose, two Landsat TM images from 2004 to 2011 are used to extract land use. The unsupervised interpretation is classified into open area, paddy field, farming area, scrub, savanna, secondary forest and primary forest. Then classified land use into 5-density class i.e. no vegetation (open area), sparse vegetation (paddy field), medium vegetation (farming area, shrub, and savanna), high vegetation (secondary forest) and dense vegetation (primary forest). Afterward, the difference of land use between 2004 and 2011 is generated to gain insight whether the land use change is negatively or positively developed during the study period. Results confirmed that the significant decrease in 2004 to 2011 of land use change (LUC) observed in No vegetation (-7.59%) and dense vegetation class (-5.7%) while the increased LUC found in the class of medium vegetation (5.66%) and high vegetation (5.21%). Moreover, landslides have occurred 128 times since 2012, and the most frequent are in 2013. Landslides have occurred most dominant in the one with the LUC from high vegetation to medium vegetation on slope 30 – 40 degrees. In conclusion, the global LUC in Ujung-Loe watershed indicates significant effect to landslides occurrence and slope instability.