Impact of surface water management on groundwater mixing in Alpine catchments

• Applicants: Professor Dr. Gabriele Chiogna; Professorin Dr. Barbara Wohlmuth
• Subject Area: Hydrogeology, Hydrology, Limnology, Urban Water Management, Water Chemistry, Integrated Water Resources Management
• Term: since 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 418892319

Geophysical flows are generally characterized by complex spatial and temporal dynamics, which often control solute spreading, dilution and reactive mixing. Inefficient mixing, typical of flows occurring at low Reynolds numbers, such as groundwater flows, may significantly decrease the effective reaction rate observed in the system. Mixing is particularly relevant for environmental pollution of groundwater bodies since it may hinder contaminant degradation. Considering mixing limited conditions, the topology of the flow field and kinematic processes such as stretching and folding occurring at multiple spatial and temporal scales play a pivotal role in the quantification and understanding of the fate and transport of contaminants. Our hypothesis in this project is that the dynamic interaction between surface water and groundwater is of pivotal importance to properly quantify mixing in porous aquifers. In particular, we aim at investigating how surface water management in Alpine catchments affected by strong anthropogenic impacts (i.e., hydropeaking generated by hydropower production) controls mixing processes at multiple temporal scales (subdaily, daily, weekly, seasonal) in aquifers. The project aims at developing and applying appropriate topological and kinematic metrics which can be used as predictors of mixing, at developing novel numerical approaches to solve inverse problems under such complex and transient conditions and at estimating parameter uncertainty. Beside numerical simulations, the methods developed in this project will be tested in a real case study, i.e., the Adige aquifer in Trento, Italy. The novelty of the proposed research lays in the investigation of i) the impact of surface water management in Alpine catchments on groundwater flow in alluvial aquifers (i.e, beyond the hyporheic zone); ii) the influence of highly transient interface transmission conditions on the topology of the two dimensional and three dimensional groundwater flow fields; iii) the development of accurate inversion numerical schemes for the solution of the flow equation under highly transient boundary conditions; iv) the quantification of the uncertainty related to model prediction considering both hydrogeological parameter uncertainty as well as the uncertainty affecting transient interface conditions.

• DFG Programme: Research Grants
• Co-Investigators: Professor Dr.-Ing. Markus Disse; Steven Mattis, Ph.D.