The impact of peatland restoration on the site hydrology of an abandoned block-cut bog

Artificial drainage networks established throughout peatlands during the peat extraction process often remain active following abandonment, maintaining a water table relatively far from the surface of the peat, and hindering the survival and reestablishment of Sphagnum mosses. As an initial restoration effort, the primary drainage network of an abandoned cutover peatland was blocked with a series of peat dams, consequently reducing the runoff efficiency and causing the site-average water table to rise by 32 cm. Higher water tables and a blocked drainage network resulted in increased runoff variability, dependent upon antecedent conditions (capacity to retain additional water on-site), and event-based precipitation dynamics. Evapotranspiration (ET) rates were 25% higher following rewetting (3.6 mm day-1) compared to prerestoration ET rates of 2.7 mm day-1. Total storage changes were restricted following rewetting, as a factor of the reduced runoff losses limiting water table drawdown, thereby constraining peat compression and preventing undue drying of the unsaturated zone. An average surface level rebound of 3 cm was observed, increasing the mean hydraulic conductivity by an order of magnitude. Changes to the system hydrology following restoration efforts produced hydrological conditions more favourable for the recolonization of Sphagnum mosses.