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Landslide is one of the most common natural disasters in Indonesia. In Lut Tawar Lake, specifically the cliff side, the landslide event occurs almost daily. Mitigation effort becomes a necessity following the fatality cases it causes. This study aimed to identify landslides and suitable mitigation for the case of Lut Tawar's lake cliff. A combined approach of landslide survey and image interpretation with field validation was used. In addition, local vegetation surrounding the case area was identified from the survey and interview process. The results showed there are in total 37 landslide points in the study area. The conducted analysis showed the landslide was mainly caused by land use change from forest to a plantation, slope, particularly in the cliff area that was carved for road development, the volcanic geology of Bukit Barisan mountain, rainfall intensity, and the equatorial rainfall characteristic of the study area. The results also suggest the finest solution for landslide mitigation, namely the eco-engineering approach, a revegetation method using the local vegetation. Local vegetation comprises multiple strata, of which grass in the below strata, shrubs in the middle strata, and trees in the upper strata, constitute a shield for the lake cliff. Within this structure, government and community can cultivate these plants in the surrounding lake area. [ABSTRACT FROM AUTHOR]

Having an area of approximately 57,8 km2, a perimeter of 46,12 km, and a water catchment area of about 246,5 km2, Laut Tawar Lake has undergone siltation which was allegedly caused by soil erosion from the water catchment area, leading to sedimentation of water bodies. This study aims to map vulnerable areas and calculate the erosion rate of the Laut Tawar Lake for the purpose of providing information on the spatial layout and development design of the lake water catchment area. We use remote sensing and geographical information system to map areas vulnerable to erosion. For analyzing the potential erosion rate, we adopt the Universal Soil Loss Equation (USLE) approach. Our result showed erosion rate occurred in the Laut Tawar Lake ranged from very low to very high. In addition, erosion is also sparsely distributed in Laut Tawar Lake. The high erosivity index, domination of area more than 45% slope, and land use change from forest to the agricultural area in the study area become the main driver of the erosion. Analysis of the potential erosion rate of Lake Laut Tawar shows an increase from 1990 to 2019. Erosion was 12.4 tonnes/ha/year in 1990, 11.0 tonnes/ha/year in 2000, 14.6 tonnes/ha/year in 2009, and 27.4 tonnes/ha/year in 2019. The spatial distribution of erosion shows an increasing trend from year to year. The results of the overlay with villages in lake catchments show that 66 percent of villages are in the high and very high categories in the last year. The study suggested conservation through revegetation using local species as the best solution for the erosion issue in the lake cliff area. The vegetation also plays a crucial role as a soil cover that protects the soil from rainfall kinetic energy that led to erosion. [ABSTRACT FROM AUTHOR]