 |
| Titel |
Quantifying groundwater contribution to the summer water-budget of a northern peatland complex, Schefferville, Québec, Canada |
| VerfasserIn |
Bernard Brixel, Jeffrey McKenzie |
| Konferenz |
EGU General Assembly 2010
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250043107
|
|
|
|
|
|
| Zusammenfassung |
| Northern peatlands are one of the largest, naturally occurring terrestrial stores of soil
carbon and are an important component of the global carbon cycle. These systems
are predominately water-saturated with the average water table position situated
close to the land surface. Fundamental questions remain as to the role of deeper
groundwater systems in influencing the origin and development of peatlands and how
groundwater and surface water interactions control the internal movement of water.
The hydrology of a 0.095 km2 peatland, located 20 km southeast of Schefferville
Quebec, was studied to quantify and characterize the spatiotemporal contribution of
groundwater from sub-peat deposits (>2m depth). The study site is of particular
interest because it exhibits both ombrotrophic (rain-fed) and minerotrophic (rain
and groundwater-fed) features drained by a single stream at the peatland outlet. A
three-dimensional groundwater flow model, the finite-difference U.S. Geological Survey
MODFLOW code, is used to simulate the peatland and characterize the groundwater flow
system. The model is parameterized with data measured from June 17th to September
4th, 2009, including continuous meteorological measurements from an automatic
weather station, 14 observation wells, and two 90° V-notch weirs. Over the study
period there was an average precipitation of 65 mm month-1, a calculated potential
evapotranspiration of 46 mm month-1, and the average surface discharge from the peatland
was 1.64Ã1013 mm3 month-1, or a specific discharge of 174 mm month-1. The hydraulic
conductivity of the peat was calculated from head-recovery tests at 500 and 1000 mm
depths and average values were 10-2 and 10-3 mm s-1 respectively. The estimated
baseflow contribution was 9.60Ã1012 mm3 month-1, or a specific baseflow of 101
mm month-1. The correspondence between stream stage and groundwater level
fluctuations, in addition to the relatively large baseflow component of runoff, supports the
hypothesis that groundwater plays a dominant role in this peatland flow system. We
determined, based on field measurements, that upward groundwater flow from below
the peat column is an important flow path through which water contributes to the
peatland hydrologic budget, and implies that vertical flow is essential in certain
peatlands. |
|
|
|
|
|
|