A hydraulic parametrization is developed for peatland environments in the C
anadian Land Surface Scheme (CLASS). Three wetland soil classes account for
the typical variation in the hydraulic characteristics of the uppermost 0.
5 m of organic soils. Review of the literature reveals that saturated hydra
ulic conductivity varies from a median of 1.0 x 10(-7)m/s in deeply humifie
d sapric peat to 2.8 x 10(-4) m/s in relatively undecomposed fibric peat. A
ver age pore volume fraction ranges from 0.83 to 0.93. Parameters have been
designed for the soil moisture characteristic curves for fibric, hemic and
sapric peat using the Campbell (1974) equation employed in CLASS, and the
van Genuchten (1980)formulation. There is little differance in modelled soi
l moisture between the two formulations within the range of conditions norm
ally found in peatlands. Validation of modelled water fable depth and peat
temperature is performed for a fen in northern Quebec and a bog in north-ce
ntral Minnesota. The new parametrization results in a more realistic simula
tion of these variables in peatlands than the previous version of CLASS, in
which unrealistic mineral soil "equivalents" were used for wetland soil cl
imate modelling.