Subsurface heterogeneity is a well-known feature at hillslopes (preferential flow) or weathered rock (karstification). However, recent research (e.g., Jasechko & Kirchner, 2016) provides evidence that fast flow peaths exist in almost all types of hydrological systems.

The aim of this work is to test a model that includes the heterogeneity of selected subsurface characteristics (soil and rock storages and hydraulic conductivities) for its applicability in marl dominated systems. Automatic calibration and sensitivity analysis schemes will be applied to evaluate the model and the identifiability of heterogeneous subsurface characteristics by the modeling approach.

Precipitation (daily), discharge (daily), and water quality data (forthnightly) is available for 4 marl dominated catchments in Luxembourg (4-160km²). The model VarKarst (Hartmann et al., 2013a) is programmed in Matlab and ready to be used, as well as the routines for uncertainty analysis. The model will be applied on all catchments and in an iterative evaluation procedure (similar to Hartmann et al. 2013b), model deficiencies will be identified until the model provides reasonable performance and plausible results. The identifiability of the model parameters that control the simulated heterogeneity of this final version will reveal whether heterogeneity is important to be included (under the current data availability). Along the course of the MSc thesis support to visit the study sites and the 2nd advisor of the thesis at the Luxembourg Institute of Science and Technology can be provided.

This MSc thesis will require to apply and further develop skills and data processing and analysis (Excel, R), as well as processing and visualizing spatial information (GRASS or ArcGIS). General knowledge about modelling and model evaluation is necessary BUT knowing Matlab programming language is NOT a mandatory skill (a ready-to work version of the model including model diagnostics and support for necessary modifications will be provided by the supervisor). Collaboration with MSc students working with the same model is possible but not required.

The successful conduction of the thesis will prepare the student to work in national and international consultancies, governmental offices and research. The topic and task of the thesis will be adapted to the desired future working field of the student and mentoring for a successful start into the first job will be provided by the supervisor.

Andreas Hartmann, Julian Klaus (Luxembourg Institute of Science and Technology)

Andreas Hartmann andreas.hartmann@hydrology.uni-freiburg.de Tel. +49 (0)761 / 203-3520

Data and model code will be readily available. The task of this work is the iterative adaption of the model code to the new settings of the marl dominated study sites. This requires the willingness and some experience in programming. Preliminary/basic knowledge of Matlab is an asset but as R is quite similar, this thesis topic will also be easily accessible for students without particular experience in Matlab.

Preferably in English.

Hartmann, A., Barberá, J.A., Lange, J., Andreo, B., Weiler, M., 2013. Progress in the hydrologic simulation of time variant recharge areas of karst systems – Exemplified at a karst spring in Southern Spain. Adv. Water Resour. 54, 149–160. doi:10.1016/j.advwatres.2013.01.010

Hartmann, A., Wagener, T., Rimmer, A., Lange, J., Brielmann, H., Weiler, M., 2013. Testing the realism of model structures to identify karst system processes using water quality and quantity signatures. Water Resour. Res. 49, 3345–3358. doi:10.1002/wrcr.20229

Jasechko, S., Kirchner, J.W., Welker, J.M., Mcdonnell, J.J., 2016. Substantial proportion of global streamflow less than three months old. Nat. Geosci. doi:10.1038/NGEO2636