Monitoring Ground Deformation in Tropical Peatland Landscapes Using a PSDS-InSAR Multi-Sensor Approach: A Case Study of Palangkaraya

Peatlands play a crucial role in maintaining global climate balance due to their ability to store large amounts of carbon and act as a sink for greenhouse gas emissions such as methane and carbon dioxide. However, peatland ecosystems have been increasingly degraded due to deforestation, infrastructure development, and land conversion, leading to land subsidence and higher CO2 emissions. This issue leads to disaster risks such as ecosystem disturbance, increased flood risk, and infrastructure damage. Central Kalimantan Province, particularly in the Palangkaraya area, is among the regions with extensive peatland areas affected by this phenomenon. This study aims to analyze the pattern and velocity of vertical deformation using the Persistent Scatterer-Distributed Scatterer Interferometric Synthetic Aperture Radar (PSDS-InSAR) approach, based on Sentinel-1 and ALOS PALSAR-2 imagery acquired between 2017 to 2022. This method combines the advantages of Persistent Scatterer (PS) techniques for urban areas and Distributed Scatterer (DS) techniques for vegetated areas to increase deformation pixel density, thereby yielding broader spatial coverage. Data processing was performed using software from the ISCE Framework, with results validated against groundwater level data. Land subsidence observed in the Palangkaraya peatland area aligns with the hydro-climatological conditions of the region. A distinct pattern of land subsidence is evident during the dry season, accompanied by a decline in groundwater levels in the next few days. The velocity of ground deformation varies from -2.24 to 2.36 cm/year for Sentinel-1 and -1.31 to 1.08 cm/year for ALOS PALSAR-2, with RMSE values of 0.4279 cm/year and 0.6351 cm/year, respectively.