HR: 0800h
AN: H71C-04    [Abstracts]
TI: Ecohydrological Processes in Cutover Peatlands: The Impact of Peatland Restoration (Rewetting) on the Site Hydrology and Water Balance of an Abandoned Block-cut bog in Quebec
AU: * Ketcheson, S J
EM: sjketche@uwaterloo.ca
AF: Dept. of Geography & Environmental Management, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L3G1, Canada
AU: Price, J S
EM: jsprice@uwaterloo.ca
AF: Dept. of Geography & Environmental Management, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L3G1, Canada
AB: 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. In an effort to restore a suitable hydrological regime, the primary drainage network of an abandoned cutover peatland (the Cacouna bog) was blocked with a series of peat dams, resulting in a site-averaged water table rise of 32 cm. The components of the water balance and site hydrology were monitored over three consecutive study periods (2005-2006 prior to rewetting; 2007 following rewetting), permitting quantification of the altered hydrologic conditions due to rewetting. Following ditch blocking, runoff was reduced from 23 to 10% of precipitation during the 2005/2006 (two-year average) and 2007 seasons, respectively. The higher water table and blocked drainage network resulted in increased runoff variability, dependant upon antecedent conditions (capacity to retain additional water on-site) and event-based precipitation dynamics. Evapotranspiration (ET) remained the major water loss from the site in each year, comprising 91, 77 and 91% of total outputs during the 2005, 2006 and 2007 seasons, respectively. ET rates were 25% higher in 2007 following rewetting (3.6 mm/day), compared to pre-restoration ET rates of 2.7 mm/day during both the 2005 and 2006 study periods. Storage changes were restricted following rewetting, due to 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. There is a need to understand the impact of site rewetting on the system hydrology, to facilitate a timely return to a functioning ecohydrological state following disturbance. The intention of this presentation is to provide an overview of the hydrological regime prior to, and following, rewetting.
DE: 1803 Anthropogenic effects (4802, 4902)
DE: 1813 Eco-hydrology
DE: 1876 Water budgets
DE: 1890 Wetlands (0497)
SC: Hydrology [H]
MN: 2009 Joint Assembly