Widely present in boreal regions, peatlands contain large carbon stocks because of their hydrologic properties and high water content, making decomposition smaller than primary productivity. We have enhanced the global land surface model ORCHIDEE by introducing northern peatlands. These are considered as a new Plant Functional Types (PFT) in the model, with specific hydrological properties for peat soil. In this paper, we focus on the representation of the hydrology of northern peatlands and on the evaluation of the hydrological impact of this implementation. A prescribed map based on the inventory of Yu et al. (2010) defines peatlands as a fraction of grid cell represented as a PFT comparable to C3 grasses with adaptations to reproduce shallow roots and higher photosynthesis stress. The treatment of peatland hydrology differs from that of other vegetation types by the fact that runoff from other soil types is partially directed towards the peatlands (instead of directly to the river network). The evaluation of this implementation was carried out according to different spatial and temporal scales, from site evaluation to larger scales such as watershed scale and all northern latitudes scale. The simulated net ecosystem exchanges are in agreement with observations from 3 FLUXNET sites. Water table positions were generally close to observations, with some exceptions in winter. Compared to other soils, the simulated peat soil have a reduced seasonal variability of water storage. The seasonal cycle of inundated peatlands area is also compared to flooded area estimated from satellite observations. The model is able to represents more than 89.5 % of the flooded areas located in peatlands areas, where the modelled extent of inundated peatlands reaches 0.83 Mkm<sup>2</sup>. However, the extent of peatland in northern latitudes is small enough that is does not impact the terrestrial water storage at scale of latitudes over 45° N. Therefore, the inclusion of peatlands has a weak impact on the river discharge located in boreal regions.
Largeron, C., Krinner, G., Ciais, P., & Brutel-Vuilmet, C. (2018). Implementing northern peatlands in a global land surface model: Description and evaluation in the ORCHIDEE high-latitude version model (ORC-HL-PEAT). Geoscientific Model Development, 11(8), 3279–3297. https://doi.org/10.5194/gmd-11-3279-2018