A high-resolution transient 3-dimensional hydrological model of an extensive undisturbed bog complex in west siberia

Abstract

Data on the distributed dynamics of water table elevation (WTE) and on the variation of water discharge are needed for calculation of the carbon balances of entire mire complexes. Here we describe the development of a high-resolution transient hydrological model for the extensive boreal bog complex at Mukhrino in West Siberia (Asian Russia). The model, developed in PCRaster-MODFLOW, outputs spatially distributed WTE and daily water fluxes in 3D. It incorporates snowmelt dynamics and temporal freezing of the upper peat layer. During the period 2008−2016 snowmelt occurred during 2−4 weeks per year and accounted for 30 % of the total volume of water available for recharge and evapotranspiration. The calibrated hydraulic conductivity of the acrotelm was 0.6−1.2 cm s-1. Model outputs indicated that the annual amplitude of WTE variation was 10−20 cm, in agreement with on-site measurements. Snowmelt raised the water table by 5–10 cm at the water divide and by 10–20 cm near the margin of the bog. In the ridge-hollow complex on the mire expanse, 91 % of all spring water fluxes discharged through the acrotelm in hollows, whereas the ridges retarded runoff. Based on modelled water fluxes and measurements of DOC we estimated that the organic carbon (DOC) export from the bog complex was 7.7 g m-2 y-1.