Abstract
Drainage canals associated with logging and agriculture dry out organic
soils in tropical peatlands, thereby threatening the viability of
long-term carbon stores due to increased emissions from decomposition,
fire, and fluvial transport. In Southeast Asian peatlands, which have
experienced decades of land use change, the exact extent and spatial
distribution of drainage canals are unknown. This has prevented
regional-scale investigation of the relationships between drainage, land
use, and carbon emissions. Here, we create the first regional map of
drainage canals using high resolution satellite imagery and a
convolutional neural network. We find that drainage is
widespread-occurring in at least 65% of peatlands and across all land
use types. Although previous estimates of peatland carbon emissions have
relied on land use as a proxy for drainage, our maps show substantial
variation in drainage density within land use types. Subsidence rates,
and corresponding carbon losses from decomposition, are 3.2 times larger
in intensively drained areas than in non-drained areas, highlighting the
central role of drainage in mediating peat carbon fluxes. Accounting for
drainage canals was found to improve a subsidence prediction model by
30%, suggesting that canals contain information about subsidence not
captured by land use alone. Thus, our dataset can be used to improve
carbon emissions predictions in peatlands and to target areas for
hydrologic restoration.