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The soil-groundwater-stream continuum: Measurements and implications

Gunnar Lischeid1, Christoph Merz1, Pavel Krám2
1 Institut für Landschaftswasserhaushalt, Leibniz-Zentrum für Agrarlandschaftsforschung
2 Czech Geological Survey

O 6.1 in Grundwasser-, Boden- und Oberflächenwasser-Interaktionen

30.05.2014, 11:00-11:20, H19, NW II

Rainwater infiltrates into the soil, seeps down to the groundwater, and eventually discharges into streams or lakes. The hydrological soil-groundwater-stream continuum is reproduced in numerous models. Experimental field work and data analysis, however, is usually organised within different disciplines and hardly considers the continuum approach. Correspondingly there is a lack of adequate approaches to quantitatively determine the hydrological continuum.

The approach presented here is based on the assumption that any observed change in soil hydrological, groundwater head or discharge time series is due to a response to an input signal (rainfall, snow melt) into the hydrological system. It is usually to a certain degree related to mass transport, although pressure propagation might prevail in confined aquifers. Catchments as soil-groundwater-stream continuums act as low-pass filters that damp and delay the input signal. It could be shown that the observed signals in either compartment can be regarded as a superposition of the signals of the respective flowpaths.

That transformation of the input signal along its way through the soil-groundwater-stream continuum can be determined quantitatively using a principal component analysis of the respective time series. This measure can then be used, without requiring application of a numerical model, to

·         Determine first order controls of the observed dynamics;

·         To assess the effects of structural heterogeneities on the observed dynamics;

·         To determine mean “representative” behaviour at a larger scale;

·         To better understand diverging trends;

·         To identify additional impacts on the observed dynamics, e.g., groundwater withdrawal.

This information can then be used to better constrain hydrological and hydrogeological models. Thus, groundwater or discharge data can be used to reduce the uncertainty or noise of soil hydrological data and vice versa. Examples will be given from different catchments both in mountainous and lowland areas.

 



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Letzte Änderung 30.10.2013