Mapping Subsidence of Tropical Peatlands

Tropical peatlands in Southeast Asia have been rapidly drained and deforested in recent decades. The resulting lowering of the water table leads to the decomposition of long-term peat carbon stocks, resulting in widespread subsidence and CO2 emissions. Prior efforts to map tropical peatland subsidence relied on manual measurements with subsidence poles anchored beneath the peat. In this work, we demonstrate the potential for InSAR remote sensing to map peatland subsidence across Southeast Asian peatlands. We measure rates of peatland subsidence at 90m resolution across 2.7Mha of peatland area from 2007-2011. This approach enables subsidence measurements across a diverse range of land use classes on peatlands, including plantations, smallholder agricultural areas, ferns, shrubs, and degraded forests. Across the surveyed area, we find over 90% of peatlands are subsiding, with a mean rate of 2.2 cm/yr. This method offers great promise for peatland management and conservation by allowing us to identify subsidence hotspots. We also use subsidence maps to calculate emissions factors across different land uses and estimate total regional CO2 emissions from peat oxidation.