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| Titel |
Impacts of ditch cleaning on hydrological processes in a drained peatland forest |
| VerfasserIn |
H. Koivusalo, E. Ahti, A. Laurén, T. Kokkonen, T. Karvonen, R. Nevalainen, L. Finér |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 12, no. 5 ; Nr. 12, no. 5 (2008-10-14), S.1211-1227 |
| Datensatznummer |
250010881
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| Publikation (Nr.) |
 copernicus.org/hess-12-1211-2008.pdf |
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| Zusammenfassung |
| One fourth of the forests in Finland are growing on drained peatlands.
Forestry operations such as ditch network maintenance increase the export of
suspended solids and nutrients, and deteriorate water quality in lakes and
rivers. Water protection presupposes an understanding of how forestry
operations affect peatland hydrology. The objective was to study the
hydrological impacts of ditch cleaning on the basis of water table level and
runoff measurements from two pairs of artificially delineated catchments in
drained peatland forests in Finland. Data from treated and control
catchments indicated that ditch cleaning lowered the level of the water
table in sites where a shallow peat layer was underlain by mineral soil. In
sites with deep peat formation, the water table showed no detectable
response to ditch cleaning. Runoff data suggested that annual runoff clearly
increased after ditch cleaning, which was in conflict with the previously
reported small impacts of ditch network maintenance. The hydrological model
FEMMA was calibrated and applied to assess the conformity of the data and
the experimental setup. In the model application, the catchments were
assumed to behave as independent hydrological units. However, assessment of
the model results and the measurements suggested that ditch cleaning had an
impact on hydrological measurements in both treated and control catchments.
It appeared that the independence assumption was violated and there was a
hydrological connection between the artificial catchments and, therefore,
the results of the data analysis were considered misleading. Finally, a
numerical experiment based on the model simulations was conducted to explain
how the assumed relationship between soil moisture and transpiration is
reflected in the modelled runoff. Modelled runoff decreases and evaporation
increases when ditches are cleaned in poorly drained sites, where the
initial ditch depth is small and the depth of a highly conductive topsoil
layer is low. The numerical experiment can be applied to assess when ditch
cleaning does not improve evapotranspiration and is unnecessary. |
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