Land Subsidence Affects Coastal Zone Vulnerability

Vast development of urban cities in coastal area has caused rapid degradation of the environment. Coastal zone vulnerability is mainly influenced by sea level rise, land subsidence, storm surge, sediment transport, socio-economic and coastal management policies. Present study investigates the main factor influences coastal vulnerability of developing coastal urban city at north coast of Java. Two factors were observed in the study; firstly land subsidence was observed by geodetic and leveling methods. Secondly, tidal inundation was measured by field work and participatory mapping. Tidal inundation model was performed using spatial model. Physical vulnerability model was conducted by scoring and weighting. The results show that Average rate of land subsidence between 2003-2014 is -0.021 (0.0-0,091) m.yr^-1. Tidal inundation in 2014 covering 1286.29 hectares, where the highest impact happened at brackish water pond (969.63 ha). Tidal inundation prediction on 2031 will inundate 1786.76 ha, which the largest tidal inundation is in the residential area (646.85 ha). Coastal zone vulnerability in the research areas predominantly was influenced by land subsidence, and classified in moderate vulnerable. Land subsidence happened due to most of research areas are consists of alluvial plains morphology units that are still in consolidation process. Land subsidence conditions strongly influence the extent of tidal inundation in the future.