Two dimensional hydrological simulation in elastic swelling/shrinking peat soils

Peat soils respond to drying/wetting cycles due to evapotranspiration and precipitation with reversible deformations induced by variations of water content. This process results in short-term vertical displacements of the soil surface and induces variations in the peat hydraulic properties that cannot be neglected when dealing with water flow problems in peatlands. A constitutive model describing swelling/shrinkage dynamics in peat soils under unsaturated conditions is implemented in a finite element simulator of Richards’ equation. The model entails a significant modification of the general storage capacity term. The contribution of the saturated zone to the total deformation is taken into account, using the theory of primary consolidation in the hypotheses of completely reversible volume changes and constant compressibility. Simulations have been carried out for a drained cropped peatland south of the Venice Lagoon (Italy), for which a large data set of hydrological and displacement measurements has been collected since the end of 2001. The considered domain is a field section bounded by ditches, subject to rainfall, evapotranspiration, and lateral drainage. The comparison between simulated and measured quantities demonstrates the capability of the model to accurately reproduce both the hydrological and deformation dynamics of peat.