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| Titel |
Groundwater transit time distribution and transfer of nitrates from soils to
river network |
| VerfasserIn |
Tomasz Michalczyk, Dominika Bar-Michalczyk, Marek Dulinski, Jarosław Kania, Grzegorz Malina, Kazimierz Różański, Tadeusz Szklarczyk, Przemysław Wachniew, Stanisław Witczak, Damian Zięba, Anna Zurek |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250131058
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| Publikation (Nr.) |
 EGU/EGU2016-11413.pdf |
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| Zusammenfassung |
| Measures undertaken to reduce nitrate loadings of agricultural origin to surface waters have
to take into account delays associated with pollution transport between the root zone and
groundwater abstraction wells or natural discharge zones. Parts of an important
fissured-carbonate aquifer (Major Groundwater Basin No. 326) located in southern Poland
are polluted, with concentrations of nitrates significantly exceeding the European Union limit
of 50 mg/L. The polluted groundwater discharges to the streams of the Kocinka river
catchment affecting their water quality.
The MODFLOW and MT3DMS codes were used to model flow and transport of
contaminants in the aquifer. Transport of conservative solutes was performed in a transient
mode, with the steady-state flow field calibrated using present-day distribution of hydraulic
heads and discharges of streams draining the aquifer. Time series of tritium data available for
21 production wells and springs, some of them extending over the period of 30
years, were used for calibration of flow and transport model resulting in significant
changes in the original conceptual framework of this groundwater system. The
regional-scale numerical model of flow and transport allowed for identification
of the gaining stream reaches and for estimation of groundwater contributions to
streamflow. Observations of in stable isotope composition and stream water chemistry
confirmed the results of the numerical model for these particular stream reaches.
The numerical model provided also the transit time distribution of groundwater
flow through the saturated zone with an average value of 8 years and dominant
transit times in the range from 3 to 20 years. Transit times of water through the
unsaturated zone are in the range from less than 5 to 25 years with an average value
of 10 years. Because of these delays, the results of measures aimed at reducing
nitrate loads to the river network will be visible only within the relevant timescales. |
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