Modelling water fluxes on different scales in alpine catchments
Complementary Chinese topic:
We have substantial experience in the conduction of hydrogeophysical field work at high altitudes (Tibet). This includes (i) installing piezometers and data-loggers to measure hydraulic head, (ii) interpreting hydraulic measurements of head, (iii) conducting hydrogeological field tests such as pump tests, slug tests, and their interpretation, (iv) taking soil samples and perform grain-size analyses, (v) perform ex-site Darcy experiments to determine hydraulic conductivity, (vi) perform a variety of geophysical field methods (S6). We have successfully applied these methods in the Nam Co area, Tibet. However, this orchestra of hydrogeological and geophysical tools can be applied to any other alpine catchment in order to answer a variety of topics including sediment transport, freeze-thaw cycles, small- (Richards flow) and large-scale (groundwater flow) water fluxes, as well as method development to constrain hydrogeophysical parameters (e.g. hydraulic conductivity).
A combined field campaign including hydrogeological as well as geophysical methods will be used to constrain hydraulic conductivity (K) along singe boreholes. A series of geophysical (geoelectric) measurements of hydraulic conductivity both along the land surface as well as along boreholes will be completed in order to obtain depth-resolved K values. That parameter (K) is important to develop water flow models on different scales. On a small scale, unsaturated (Richards) flow requires K in order to understand the freeze-thaw cycle more closely. Climatic change will affect the seasonal freeze-thaw cycle. Understanding the freeze-thaw cycle is therefore important to assess the amount of released CO2 to the atmosphere. On a large scale, groundwater fluxes are also dependent on K, and they will be used to assess rates of sediment transport. Numerical models will be provided to simulate water fluxes on small and large scales.
Cooperation within TransTiP
close collaboration with project S6 providing information on permafrost-distribution and geophysical properties
Sino-German complementarity of research
Chinese partners will focus on soil erosion and sediment transport observation. For this, flow models are required, provided by W4. W4 will also provide information on the distribution of K in regarded aquifer systems. Project S6 will therefore provide input to constrain K values from combined hydrogeological and geophysical exploration.
Prof. Dr. Thomas Graf, LU Hannover Prof. Dr. Andreas Hördt, TU Braunschweig Prof. Dr. Fan Zhang, ITP-CAS