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| Titel |
Modeling mountainous fens water regime using 18-O. |
| VerfasserIn |
Martin Sanda, Dora Šípová, Michal Dohnal, Milena Cislerova |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250042794
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| Zusammenfassung |
| Mountainous fens are important hydrological component of the headwater catchments in
Jizera Mountains, The Czech Republic. Experimental catchment UhlíÅská (1.78 km2) is
formed by paleozolic crystalline bedrock overlaid by shallow highly permeable Cambisol on
the hillslopes, whereas the thick saturated glacial deposits in the valley are overlaid by
Histosols. Standard meteorological and hydrological monitoring is supplemented by
measurements of the soil moisture, soil pore water suction, water table fluctuation in the
saturated riparian zone of Äerná Nisa creek. Water sampling for the 18O and 2H isotopes is
performed throughout the catchment.
Numerical simulation was performed with S1D code for the period May 2007-September
2008. The model is based on Richards’ equation for vertical soil water flow and the
advection-dispersion equation for transport of stable oxygen isotope 18O. Hourly rainfall or
daily snowmelt intensities are introduced as an upper boundary condition, the measured
groundwater table fluctuation serves as a time variable prescribed head at the bottom
boundary. The intensity of the root water uptake due to transpiration is assumed as a zone
sink term. Daily values of δ18O in the rain and weekly δ18O values of the melting snow,
together with the hourly interpolated monthly values of δ18O in the groundwater, serve as the
transport boundary conditions. Measured soil hydraulic parameters were adjusted based on
suction heads and δ18O variations in observation points representing the soil tensiometers and
suction cups.
Results of the model demonstrate a strong mixing of water in the root zone of the peat
profile, where evapotranspiration takes place. Process of deeper percolation is limited
by the high degree of saturation of the peat in combination with its low hydraulic
conductivity. The seasonal water percolation is estimated according to the results of the
isotope transport down to 70 cm below the surface. The S1D model with the use
of environmental isotope as a natural tracer is a useful tool to asses the flow in
the porous media where environmental isotopes help to constrain hydrological
hypotheses.
The research is supported by the Czech Science Foundation projects No. 205/09/0831,
No. 205/08/1174 and by IAEA research contract 14007. |
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