LAND SUBSIDENCE DYNAMICS IN MALAYSIA BASED ON TIME-SERIES VERTICAL DEFORMATION USING MODIFIED D-INSAR SENTINEL-1

Abstract

Land subsidence in urban areas is geohazard that can be caused by tectonic movements, changes in aquifer networks, or anthropogenic activities such as excessive groundwater extraction, mining, tunnelling, and plantations. The degree of land subsidence can be monitored using time-series vertical deformation data extracted from Sentinel-1 satellite imagery using the modified D-InSAR method. This study aims to determine the land subsidence dynamics of 16 cities in Malaysia based on time-series vertical deformation data, including Kota Bahru, Kuala Terengganu, George Town and Butterworth, Alor Setar, Kangar, Ipoh, Seremban, Malacca, Kuala Lumpur, Putra Jaya, Shah Alam, Kuantan, Johor Bahru, Kinabalu, Bandar Labuan (Victoria), and Kuching. The time-series vertical deformation data used in this study were extracted between 2014-2022. Negative values of vertical deformation indicate that land subsidence is occurring, while positive values of vertical deformation are indicative of regional uplift. The overall rate of land subsidence in Malaysia is between -0.5 cm to -6.0 cm, while the average uplift rate is between +0.5 cm to +4.5 cm. An analysis of the data extracted reveals that the city that is most vulnerable to land subsidence is Johor Bahru, followed by Kuala Terengganu, Seremban, Kuala Lumpur, Shah Alam, Malacca, and Kuantan, while the city that has the lowest risk of land subsidence is Kangar. In contrast, cities that are vulnerable to regional uplift are Kinabalu and Bandar Labuan (Victoria). The results of this study can be used to guide urban planning initiatives, allowing them to consider any threats that might be posed by land subsidence.