Evaluasi Terintegrasi Rembesan dan Stabilitas Bendungan Raknamo: Pembandingan SEEP/W–V-Notch dan Respons terhadap Skenario Pembebanan

Abstract

Dam-safety assessment requires integrated interpretation of numerical outputs and field monitoring while recognizing whether the compared observations represent equivalent flow domains. This study evaluates seepage at Raknamo Dam for two reservoir states, 99.68 and 104.18 m above sea level, together with slope stability under static, Operating Basis Earthquake (OBE), Maximum Design Earthquake (MDE), and rapid-drawdown conditions. SEEP/W yielded unit-width discharges of 3.0587×10⁻⁶ and 4.2983×10⁻⁶ m³/s/m. Scaling by the dam length produced section-equivalent values of 0.001376 and 0.001933 m³/s, whereas V-notch monitoring recorded 0.00360 and 0.00992 m³/s. Because longitudinal uniformity and equivalence between the modeled section and the V-notch catchment cannot be demonstrated, these quantities are not treated as equivalent observations for model validation or error estimation. V-notch data are therefore reported as independent operational monitoring evidence alongside the numerical outputs. SLOPE/W safety factors ranged from 2.082–2.504 under static conditions, 1.888–2.068 under OBE, and 1.257–1.400 under MDE. The two upstream MDE results, 1.259 at 99.68 m and 1.257 at 104.18 m, are considered practically indistinguishable at the available reporting precision because no sensitivity or uncertainty analysis was performed. The final rapid-drawdown condition after 18 h yielded a safety factor of 2.417, while the minimum factor of safety during the transient history is unavailable. The study demonstrates the value of complementary, but explicitly non-equivalent, monitoring and modeling evidence and clarifies the inference limits imposed by incomplete monitoring metadata and archived numerical-model information.