EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Processes Controlling Methane Emissions from a Tropical Peatland Drainage Canal

Lauren Somers1,2, Alison Hoyt3, Alexander Cobb4, Suhailah Isnin4, Muhammad Asri Suhip5, Rahayu Sukri5, Laure Gandois6, and Charles Harvey2,4
Lauren Somers et al.
  • 1Centre for Water Resources Studies, Civil and Resource Engineering, Dalhousie University, Halifax, Canada
  • 2Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, USA
  • 3Earth System Science, Stanford University, Stanford, USA
  • 4Singapore-MIT Alliance for Research and Technology, Singapore
  • 5Institute for Biodiversity and Environmental Research, Universiti Brunei Darussalam, Jalan Tungku Link, Brunei Darussalam
  • 6Laboratoire Ecologie Fonctionnelle et Environnement, Université de Toulouse, CNRS, INPT, UPS, Toulouse, France

Most peat domes in Southeast Asia are crisscrossed by networks of drainage canals. These canals are a potentially important source of methane to the atmosphere because the groundwater that discharges into them carries high concentrations of dissolved methane that is produced within peat. In this study, we present an isotope-enabled numerical model that simulates transport, degassing, and oxidation of methane and DIC (dissolved inorganic carbon) along a drainage canal. We then estimate methane fluxes through a five-kilometer canal that crosses a disturbed, forested, but undeveloped, peat dome in Brunei Darussalam by applying this model to field data: concentrations and stable carbon isotopic ratios of both methane and dissolved inorganic carbon from both peat porewater and canal water. We estimate that approximately 70% of the methane entering the canal is oxidized within the canal, 26% is degassed to the atmosphere, and 4% is transported towards the ocean, under low to moderate flow conditions. The flux of methane to the atmosphere is lowest at the maximum elevation of the canal, where flow is stagnant and methane concentrations are highest. Downstream, as flow velocity increases, methane emissions plateau even as methane concentrations decrease. The resulting methane emissions from the canal are large compared to emissions from the peat surface and vegetation on a per-area basis. However, since the canal covers only a small portion of the catchment area, the canal may be a substantial but not dominant source of methane from the peatland.

How to cite: Somers, L., Hoyt, A., Cobb, A., Isnin, S., Suhip, M. A., Sukri, R., Gandois, L., and Harvey, C.: Processes Controlling Methane Emissions from a Tropical Peatland Drainage Canal, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-8972,, 2023.