The study was conducted at Gampong Jawa dumpsite area, Banda Aceh, Indonesia, to delineate water table for leachate identification using 2-DERI and seismic refraction methods. The 2-DERI inverse model resistivity reveals that the area consists of two layers; top layer (reclaim; clayey sand and lateritic clay) with resistivity value of <20 Ohm-m and depth <20m; and bottom layer (marine alluvium) with resistivity value of >20 Ohm-m. The top layer of the landfill shows variation in resistivity and interpreted as possible polluted zone due to leachate infiltration from the landfill. The zone contaminated with leachate shows the resistivity value of <1 Ohm-m and <2 Ohm-m is brackish water intrusion. Seismic refraction with seismic tomography of S2 was well correlated with 2-D inverse model resistivity of R1. The result shows the water table (1571 m/s) is at depth of 5-8 m and the leachate (1229-1571 m/s) was at the same location as indicated by 2-D inverse model resistivity. The velocity of marine alluvium is 1914-2600 m/s with depth of 10-35 m and bedrock is >3286 m/s with depth of 12-50 m. 2-DERI delineates water table and subsurface boundary well. Seismic refraction is capable of delineating subsurface, but the study shows it is also capable of delineating water table boundary well even though the difference in their velocity is small.

Keywords: 2-D electrical resistivity imaging (2-DERI), seismic refraction, seismic tomography, leachate, water table

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