Evaluating the Impact of Uncertainties in Groundwater Modelling A case study of a glaciofluvial deposit investigating the effects of different boundary conditions using multiple numerical models
Publicerad
Författare
Typ
Examensarbete för masterexamen
Master's Thesis
Master's Thesis
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
Abstract
The demand for drinking water is constantly increasing around the world, which partly
entails an increased demand for groundwater of decent quality and quantity. Since ground
water is hidden beneath the ground, it is difficult to obtain a detailed comprehension of the
hydrogeological conditions of an aquifer system. Groundwater modelling is a useful tool to
increase the understanding of a current groundwater system and can be used to simulate
future scenarios and events. The aim of this thesis is to set up several groundwater
models and evaluate the impact of uncertainties regarding the conceptual understanding of
boundary conditions. The models are based on an aquifer system located in a glaciofluvial
deposit outside of Umeå Municipality (Sweden), where several geological and hydrogeological
investigations have been conducted. Based on a conceptual model of the study area,
a numerical model is set up with MODFLOW2005, to analyse how different boundary
conditions affect the model results. Manual calibration is performed on parameter values
and sensitivity analysis of different boundary conditions. The findings indicate that all
the examined boundary conditions are viable for utilization; nevertheless, it should be
noted that there can be considerable variations in the obtained results. Uncertainties in
the conceptual model, and the numerical model, are discussed and ideas for further
studies are presented. In conclusion, the geological model is the key conceptual uncertainty.
All boundary condition combinations that were tested are applicable, with the most
significant differences emerging during pumping events when the system is stressed. An
understanding of the system and the model itself is essential for identifying uncertainties
and recognising their impact on the modelling results.
Beskrivning
Ämne/nyckelord
Groundwater modelling, Groundwater model uncertainty, Conceptual model, Numerical model, MODFLOW2005, Flopy, Glaciofluvial deposit