This title appears in the Scientific Report : 2014 
Interpretation of groundwater concentration measurements using flow and transport models.
Vanderborght, Jan (Corresponding Author)
Engelhardt, Irina / Herbst, Michael / Hardelauf, Horst / van der Kruk, Jan / Klotzsche, Anja / Güting, Nils / Vereecken, Harry / Diels, Jan
Agrosphäre; IBG-3
2014
2014
7th European Modelling Workshop, Vienna (Austria), 2014-10-21 - 2014-10-23
Conference Presentation
Terrestrial Systems: From Observation to Prediction
Modelling and Monitoring Terrestrial Systems: Methods and Technologies


Concentrations measurements in samples taken from groundwater observation wells are used to monitor the evolution of the groundwater quality. Groundwater monitoring wells may be of interest to evaluate the impact of agricultural practices on groundwater quality. However, a direct interpretation of groundwater concentration measurements is impaired by several factors. Land management at the soil surface is uniform neither in space nor in time leading to spatio-temporal imprints of management practices on groundwater concentrations. In order to unravel these imprints, groundwater flow and transport models are indispensable. In this contribution, we discuss several processes that should be considered when interpreting groundwater concentration measurements in an observation well with a certain filter depth and length. First, simple analytical approaches that give a first impression about the origin of the sampled groundwater and its age are discussed. In their simplest form, these approaches consider only advective transport in a uniform aquifer. Using numerical flow and transport simulations, the impact of mixing processes and heterogeneity of aquifer properties on groundwater concentrations are presented in a second part. Since numerical simulations of 3-D processes are computationally expensive, analytical solutions of 3-D transport equations or of first-order approximations of stochastic transport equations are presented in a third part.