Statistical analysis of groundwater levels for the determination of design groundwater levels

According to the Eurocode 7 (2010), groundwater investigations shall provide information on possible extreme values and annual probabilities of exceedance of the groundwater levels, which is necessary, for example, for the planning of groundwater lowering during construction, or for the calculation of the ex-pected hydrostatic pressure on a building. Several methods based on stationary extreme value analysis exist to determine the probability of exceedance, amongst others, Fank & Fuchs (1999), Vogt et al. (2006), Fürst et al. (2015) and Lalbat et al. (2015). However, the existing methods do not account for the difficulties in determin-ing the probability of exceedance in urban areas or for non-stationary time series, with a non-zero trend. A new approach to determine the design groundwater level is proposed, which combines the advantages of the differ-ent existing methods and incorporates recent developments in non-stationary extreme value analysis. The method is in parts illustrated through an analysis of groundwater level data from the city of Munich, Germany. In addition, further statistical methodologies are applied to identify any anthropogenic influences, which are expected in urban areas, such as groundwater lowering due to the construction of underground infrastructure.