Stability Analysis And Landslide Countermeasures Using Plaxis2d In The Cigentis Watersheds, Karawang, West Jawa A’isyah Salimah 1 , Muhammad Fathur Rouf Hasan 1 {aisyah.salimah@pnj.ac.id, rouf@sipil.pnj.ac.id} Civil Engineering Department, Politenik Negeri Jakarta, Jln. Prof. Dr. G. A. Siwabessy, UI Depok 16425 1,2 Abstract. Watershed is a vulnerable environment for soil erosion to occur. High intensity rainfall causes high river water overflowed and eroded rocks as well as soil in river banks referring to landslide. Cigentis is upstream area of Citarum watershed which is functioned to arrest the water flow at the upstream in Mekar Buana, Karawang. This study aims to analyze landslide countermeasures by applying slope reinforcement and drainage refinement to prevent recurrence of slides. The methods used are survey investigation, laboratory test, stability analysis for slope reinforcement utilizing PLAXIS2D and drainage refinement. The river banks are strengthened by applying gabion mesh retaining wall. The gabion mesh dimensions are 2.5m in length; 1m in width as long as 33m. The result indicates the safety factors for existing condition 1.23 while the safety factor for strengthening condition 1.79. It can be concluded that the condition of river banks with reinforcements is in safe conditions. Keywords: Watersheds, erosion, landslide, PLAXIS2D, gabion mesh, cigentis. 1. Introduction The soil surface condition is not constantly in the form of flat area, yet it contains different topography in each area. The difference of elevation causes ground movements specifically landslide. Slide is defined as a mass movement of rocks or debris in many types such as sliding or shearing and rolling due to gravity which follow the steepness of slope [1], [2]. Rainfall could induce ground movement, the water that infiltrates to the soil and accumulates along the dipping slope would reduce the effective stress and decrease the soil shear strength. Excessive rainfall would highly trigger landslide in the seepage area of slopes. [3] revealed that landslide disaster in Indonesia is influenced by climate condition with high intensity rainfall [4]. According to compiled data from Indonesia Disaster Data Information (DIBI) of the National Disaster Management Agency (BNPB) on January 2014, Karawang regency experienced three floods in a week which are on January 13 th , 17 th , and 19 th . This floods induced landslides in several are, one of those is in Cigentis waterfall [5]. Cigentis is the upstream area of Citarum watershed which is used to hold the water at the upstream as well as the estuary for water stream. Mekar Buana village, Tegal Waru district, Karawang regency, West Java is a river flow area of Cigentis waterfall. The tilt of slope around the village is about 15⁰ - 20⁰, regarding this steep angle, landslide and floods are ICESC 2019, October 18-19, Indonesia Copyright © 2019 EAI DOI 10.4108/eai.18-10-2019.2289904