Estimation of Land Subsidence Using Sentinel Image Analysis and Its Relation to Subsurface Lithology Based on Resistivity Data in the Coastal Area of Semarang City, Indonesia

Abstract

The Semarang city is the capital of the Central Java Province that is experiencing rapid urban growth. Land subsidence in Semarang has been widely reported and its impacts can be seen already in daily life. In order to minimize its damage, land subsidence monitoring is required as a part of natural disaster mitigation. On the other hand, understanding of the subsurface lithology conditions is needed to explore the causes of subsidence in certain areas. One of the methods of monitoring land subsidence is by utilizing Synthetic Aperture Radar (SAR) satellite image which is used in this research. In turn, the subsurface lithology can be studied with the geoelectric methods, one of which is the resistivity method. The purpose of this research is to estimate the land subsidence in the Semarang city using the Sentinel Image Analysis by means of the DInSAR Method and its relation with subsurface lithology studied using the resistivity geoelectric method. The result of the research shows that the average value of subsidence was located in the Genuk District area and Semarang Utara District area which each subsidence value is 9.8 cm/year and 12.7 cm/year. This is because the lithology under the surface of the two locations is clay and silt in a soft condition that is thicker than other locations. The saltwater content contributes to the consolidation process in the lithology. There is a tendency that land subsidence is greater in the port and industrial areas than in other regions, due to building loads.

Subsurface Identification using Resistivity Method for Infrastructure Planning in Benowo Area, Surabaya City

“…Current and voltage propagation geometry influence the resistivity value calculation, by forming a half-hemispherical pattern [9]. This is calculated to determine the subsurface lithological type and fluid influence in the research location [17], [18].…”

Microzonation for Earthquake Hazards With HVSR Microtremor Method in the Coastal Areas of Semarang, Indonesia

“…Semarang City is an area that is included in the category of a moderate disaster-prone category with a disaster risk index of 183,6 (high level) in 2015 and 120,75 (moderate level) in 2018 (IRBI, 2018). The previous studies shown that the coastal area of Semarang experienced many disasters such as sea water intrusion (Suhartono, et al, 2013, Setyawan, et al, 2016, Supriyadi, et al, 2013, Wijatno, et al, 2019), tidal flood (Kuriawan, 2003, Wahyudi, 2007, Bakti, 2010, Ramadhani, et al, 2012, Handoyo, et al,, 2016 and land subsidence (Marsudi, 2000, Suhelmi, 2012, Supriyadi, et al, 2009, Abidin, et al, 2010, 2012, Widada, et al, 2020. However, the vulnerability to the earthquake disaster has not been discussed in the previous study.…”

Housing challenges in sinking coastal city: rethinking urban housing in subsidence area for a more resilient community

“…The local irreversible geo-environmental degradation, land subsidence, is a vertical displacement of the upper soil layer [4][5][6], which is mainly caused by unsustainable groundwater extraction and building loads that exceed the bearing capacity of the soil [6][7][8]. This resulted in higher coastal flooding risk [9], forcing houses and land to be submerged and abandoned [10][11][12], and the most severe: bringing the coastal areas to be completely permanently flooded [13].…”