Research Subjects

There are three main directions in the group's research activities, which can be categorized under the headlines:

• Integrated regional studies
• Theoretical methods
• Experimental studies

Integrated Regional Studies

In these studies we face the problem of sustainable water management. On a worldwide basis the most serious non-sustainable practices related to water resources include aquifer over-pumping, reduction of low flow of rivers, drying up of wetlands and soil salination. They occur as a rule in arid to semi arid regions, which are in the focus of our work, including projects in countries such as Niger, Botswana, Xinjiang (China), Usbekistan, and Tunisia. Our work in Switzerland includes the formation of floods in hilly areas, the establishment of protection zones for wells, and the cleanup of hydrocarbon spills. In these studies we develop models not only on the basis of the traditional types of data but also with new types of data including environmental tracer data, remote sensing data and geophysical data. The goal of the modelling efforts is to arrive at an increased quantitative understanding of system behaviour and to identify long-term sustainable management scenarios. Eventually we put models into an interactive form, which can be used in the education of water managers.

More detailed information of some of these studies can be found in the following powerpoint presentation:

Sustainable Water Management in Arid and Semi-arid Environments

Theoretical Methods

A large number of activities have been undertaken, devoted to the treatment of heterogeneity in natural aquifers using stochastic modelling methods. Stochastic methods calculate effective values on the large scale from small-scale statistics. On the other hand they allow to quantify the uncertainty of models. Methods from theoretical physics, such as perturbation theory, renormalization theory, homogenization theory and coarse graining were introduced into the aquifer context. We applied them to determine real mixing in aquifers, streamlines and catchment zones. Other new numerical methods, such as multi grid methods and particle methods, were also further developed for solving transport problems both with and without the occurrence of density differences.

Experimental Projects

One of our specialties is flow visualization, which through quantification with methods of image processing turns into a holistic field measurement method. We study turbulent flows using Particle Image Velocimetry (PIV) and especially Particle Tracking Velocimetry (PTV) methods, which are developed by the group in cooperation with the Institute of Geodesy and Photogrammetry. In porous media flow and transport, 3D flows and processes were visualized, using Nuclear Magnetic Resonance Imaging. Recently the potential of neutron radiography is explored together with the PSI. The results from these studies serve successfully as benchmarks for model development. Other experimental projects of the group concern tracer tests in the Grimsel rock laboratory, runoff formation on hill slopes and particle resuspension in a reservoir.

Detailed information for each current and past projects can be found in the Research Projects page