Impacts of canal blocking on fire smoke aerosol emissions in Indonesian peatlands

Abstract:

Since the 1980s, Indonesian peatlands have experienced frequent fire events due to the lowering of groundwater levels caused by extensive canal drainage for agricultural development. After witnessing a series of devastating environmental effects from fire emissions, the Indonesian government has recently engaged in various mitigation efforts, primarily through canal blocking, to restore the peatland hydrology and control fires. Canal blocking could raise groundwater level and vegetation cover, and further change the fire behaviors such as the relative proportions of flaming (surface) and smoldering (peat) combustion. To evaluate the effects of canal blocking on peatland fire emissions, we investigated the changes of the smoke aerosol emission coefficient (Ce), which is a critical parameter to convert fire radiative energy (FRP) to total smoke aerosol emissions (TPM) and is highly dependent upon fire phases with differing amounts of flaming and smoldering combustion. Specifically, annual Ce values are obtained by establishing the relationships between FRP and the TPM emitting rate during 2002-2019 fire seasons, which are derived from the MODIS active fire product and MAIAC C6 aerosol optical depth product, respectively. Then, the Ce values are evaluated using field measurements of regionally derived particulate matter emissions factors. Further, we analyze time-series Ce values during 2002-2019 to understand the longtime groundwater level impacts on Ce variations. Finally, the Ce values between restored peatlands and un-restored peatlands are compared to verify if canal blocking is altering fire behaviors in rewetted areas. This research is expected to help support the monitoring of large-scale carbon-loss mitigation activities in Indonesian peatlands.