Identifikasi Zona Lemah Tanggul Daerah Aliran Sungai (DAS) Bumang Desa Kemuja Menggunakan Metode Geolistrik Resistivitas Konfigurasi Wenner

Abstract

The Bumang Watershed is a stream of water originating from the Bumang Reservoir in Kemuja Village, Bangka Regency to hold back water from flooding the surrounding rice fields. Since the Bumang watershed embankment was built, the embankment has been damaged in the upper part of the Bumang watershed. The main cause is underground erosion. The erosion caused the embankment foundation to become weak, which was identified as a weak zone. The method used to identify weak zones in the embankment is the Wenner configuration resistivity geoelectric method. The Wenner configuration has good sensitivity to lateral changes compared to other configurations. Field data acquisition consisted of four passes with different electrode lengths and spacings. Based on the 2D cross-section of the subsurface of the Bumang watershed embankment, the weak zone is located on tracks 1, 2, and 3. On track 1 it is at a depth of 2.50 m - 3.19 m and 1.30 m - 3.19 m; on track 2 it is at a depth of 0 m - 2 m; and on track 3 it is at a depth of 0 m - 7 m, 2 m - 4.50 m, and 0 m - 4 m respectively.The Bumang Watershed serves as a drainage system originating from the Bumang Reservoir in Kemuja Village, Bangka Regency, designed to regulate water flow and prevent flooding in the surrounding rice fields. Since the construction of the Bumang Watershed embankment, structural damage has been observed, particularly in the upper section. The primary cause of this damage is underground erosion, which has weakened the embankment foundation, creating zones of structural vulnerability. To identify these weak zones, the Wenner configuration resistivity geoelectric method was employed due to its superior sensitivity to lateral variations in subsurface conditions. Field data acquisition was conducted using four traverses with varying electrode lengths and spacings. The 2D resistivity cross-section analysis revealed the presence of weak zones on tracks 1, 2, and 3. Specifically, on track 1, weak zones were detected at depths of 2.50–3.19 m and 1.30–3.19 m; on track 2, at depths of 0–2 m; and on track 3, at depths of 0–7 m, 2–4.50 m, and 0–4 m, respectively. These findings provide crucial insights into the structural integrity of the embankment and highlight the need for further assessment and potential reinforcement measures.