GROUNDWATER RUNOFF SEPARATION – TEST OF
APPLICABILITY OF A SIMPLE SEPARATION METHOD UNDER
VARYING NATURAL CONDITIONS
L. Holko (1), A. Herrmann (2), S. Uhlenbrook (3), L. Pfister (4), E.P.Querner (5)
(1) Institute of Hydrology, Slovak Academy of Sciences, Ondrasovecka 16, o31 05 Liptovsky
Mikulas, Slovakia, holko@svslm.sk
(2) Institute of Geography and Geoecology, Technical University Braunschweig, Langer
Kamp 19c, D-38106 Braunschweig, Germany
(3) University Freiburg, Institute of Hydrology, Fahnenbegrplatz, D-79098 Freiburg,
Germany
(4) CREBS - Cellule de Recherche en Environnement et Biotechnologies, CRP-Gabriel
Lippmann, 162a Ave. de la Faïencerie, L-1511 Luxembourg, Grand-Duchy of
Luxembourg
(5) Alterra, Dept. of Water and Environment, P.O.Box 47, 6700 AA Wageningen, The
Netherlands
INTRODUCTION
Groundwater runoff is an important indicator of available water resources. The separation
method introduced by Kliner and Knezek (1974) is a simple but well justified method based
on the relationship between groundwater table and stream discharge. These relatively easily
available data are often measured within the framework of regular observation networks. The
method was widely used in former Czechoslovakia to estimate groundwater runoff in
different geological conditions. In this paper we present an evaluation of the method in
several small experimental catchments in Europe (Germany, Luxembourg, Netherlands, and
Slovakia). The objective of our work was to check the results provided by the Kliner-Knezek
method against detailed knowledge and data available in experimental catchments.
METHOD
Under the existence of a hydraulic connection between the river and aquifer, a close
relationship between groundwater and stream water levels should exist. In that case, a change
in differences between groundwater table and stream water level represents groundwater
runoff. In practice, the daily groundwater runoff can be determined by plotting corresponding
values of daily discharge versus groundwater table. The top boundary concentration of dots in
the plot usually makes it possible to draw an envelope line representing the flux formed by
groundwater runoff (Fig. 1). This line can be used to calculate groundwater runoff for a
measured groundwater table.
Typically, the envelope line consists of three sections as shown in Fig.1. Groundwater
runoff separated according to section 1 should represent direct inflow of groundwater into the
stream. It is expected that section 2 represents groundwater flow plus interflow and section 3
represents conditions when increase of stream discharge is supplied by overland flow.
If groundwater table and discharge data span over a period of several years, the envelope
lines can be constructed separately for individual years, or a single master envelope line can
be used for the whole data set.
Compared to other empirical methods, the advantage of the Kliner-Knezek method lies in
the fact that it is based on measured groundwater table data. Variations of groundwater table
represent the integrated response of all processes that influence the groundwater regime.
Though the construction of the envelope is empirical, the data mostly define rather clearly
how it should be drawn. The method can provide continuous long-term estimates of
groundwater discharge. This has important implications for the practical evaluation of
groundwater resources as the data on separated groundwater runoff can be statistically treated
the same way as any other data, e.g. probability of exceedance or extremes of groundwater
runoff can be studied or groundwater recharge can be estimated.
569.0
Groundw ater table
[m a.s.l.]
3
2
568.5
1
envelope line
568.0
567.5
0
20
40
60
Discharge [l/s]
80
100
Fig. 1: Relationship between stream discharge and groundwater table in a well that represents
an aquifer hydraulically connected with the stream, envelope line and its three typical
sections
Comparisons of results obtained by the Kliner-Knezek method with isotopic runoff
separation (Holko, 1995, Holko et al., 2000) indicated that the method gives reliable
estimates of groundwater runoff. In this work we evaluate the performance of the method in
several catchments with varying natural conditions and analyze the results with respect to
detailed knowledge of hydrological behavior of the catchments gained from experimental
research.
LITERATURE
Holko, L., 1995: Application of stable environmental isotopes in hydrological research of a
mountain catchment (in Slovak). PhD thesis, Inst. of Hydrology SAS, Bratislava,
100pp
Holko, L., Herrmann, A., Schöniger, M., Schumann, S., 2000: Groundwater runoff in a
small mountainous basin (Lange Bramke, Germany): testing a separation
method based on groundwater table and discharge. In: Monitoring and Modelling
Catchment Water Quantity and Quality, Ghent, Belgium, 77-79
Kliner, K., Knezek, M., 1974: The underground runoff separation method making use of the
observation of groundwater table. (in Czech with English abstract), Journal for
Hydrology and Hydromechanics, vol. XXII, no. 5, 457-466.