On non-Darcian water flow in peat

(1) The movement of water through mires is a controlling ecological factor, since the transport of solutes by advection can dominate nutrient fluxes, determine the growth rates of survival of plants, and profoundly influence peat redox status and decomposition rates. Modelling and measuring subsurface water flows in mires requires a sound understanding of flow processes through peat. (2) The existing literature suggests that such flow violates Darcy's Law in humified peats, and casts doubt on the applicability of existing models for flow through porous media when applied to peatlands. (3) It is shown here that a large component of the reported `non-Darcian' behaviour of peat can be explained by the elastic proporties of peat compression and the effective stress principle. We argue that Darcy's Law remains an appropriate tool for use in wetland hydrologic modelling.