Fadhila Tiara Avrilia, Rini Kusumawardani, Reskizia Khasna Sajidha, Alfita Ilfiyaniingrum
The northern coastal zone of Java, particularly the Semarang–Demak corridor, is highly vulnerable due to saturated soft clay deposits, high compressibility, and rapid land subsidence. These geotechnical conditions have caused recurrent tidal inundation, accelerated shoreline retreat, and progressive degradation of coastal infrastructure. This study presents an integrated geomorphological and geotechnical assessment to evaluate coastal stability under combined structural, hydrostatic, and subsidence-induced loads. The methodology integrates Standard Penetration Test (SPT) data, finite element modeling using PLAXIS 2D, and Sentinel-1A Interferometric Synthetic Aperture Radar (InSAR) analysis to quantify subsidence rates and shoreline changes. Unlike previous studies focusing primarily on hydrodynamic processes, this research incorporates geomorphic variability into subsurface modeling, enabling more reliable predictions of soil consolidation behavior and structural response. The results indicate subsidence rates of 13.5–17.9 cm/year, exceeding natural sedimentation and significantly reducing soil bearing capacity. Numerical simulations demonstrate that untreated soft clay layers cannot support permanent infrastructure. A mitigation framework is therefore proposed, incorporating Prefabricated Vertical Drains (PVDs), geotextile reinforcement, spun pile foundations, and coastal revetment systems. The integrated approach improves overall stability, achieving a safety factor of 1.8. These findings highlight the need for site-specific coastal protection strategies addressing both geomorphological dynamics and geotechnical constraints (SDG 9 and 11). © 2026 by authors, all rights reserved.
Civil Engineering, Faculty of Engineering, Universitas Negeri Semarang, Indonesia; Department of Civil Engineering, Faculty of Engineering, Universitas Negeri Semarang, Indonesia
