Author(s): Maria Grodzka-Lukaszewska; Joachim Rozemeijer; Ype van der Velde

Linked Author(s):

Keywords: River-aquifer interaction; Velocity Oriented Approach; Head-Oriented Approach groundwater flow model; Water exchange measurement; Water exchange modelling

Abstract: The calculation of water exchange between a river and an aquifer is believed to be very important when a study considers environments where the river is the main drainage element. The systematic study on groundwater-surface water exchange carried out in 2006 by the European Community noted the importance of the conceptual models in hyporheic zones associated with the hydrogeological domain (Water Framework Directive 2006/118/WE). In the case of numerical calculations of the water exchange, using the Head-Oriented Approach (HOA) model sometimes leads to overestimating the calculated amount of water in relation to reality. The purpose of the research was to compare two conceptually different physical-mathematical models of groundwater flow, the HOA and the Velocity-Oriented Approach (VOA), by creating two corresponding numerical models and calculating the water flow in the subsoil for the same real hydrogeological situation (Hupsel, The Netherlands). For this comparison, the measurement results from the DYNAQUAL project were used. The results of this experiment served as a comparative measure of the compliance of VOA and HOA numerical models with real measurements. This research confirmed that the numerical implementation of the VOA model meets the requirements of high-precision estimation of all three components of the velocity field. The research has confirmed the VOA model's applicability in modeling groundwater flow on a local scale. Comparison of the results of the HOA and VOA models in the Hupsel catchment and their comparison with the data from the DYNAQUAL field experiment shows that the VOA model gives results closer to the measurement results in most of the modeled time steps. In the period from 1.11.2007 to 16.12.2007, the error in the volume of water fed to the channel determined by the VOA model is of the order of 19%, while the error of the volume of water supplied to the channel in the HOA model is of the order of 63%. In conclusion, it can be stated that the theoretical model of the velocity-oriented approach (VOA) is an approach that enables the determination of the water exchange flux between surface and groundwater with satisfactory accuracy. Due to the lack of numerical differentiation (typical for the HOA model), the numerical implementation of the VOA gives better estimates of the water exchange flux between the river bed/channel and more accurate approximations of the water-bearing trajectory in the immediate vicinity of the river/channel.

DOI: https://doi.org/10.64697/HIC2024_P114

Year: 2024