Author(s): Monica Basilio Hazas; Gabriele Chiogna

Linked Author(s): Mónica Basilio Hazas

Keywords: Groundwater; Hydropeaking; Mixing; Transient flow

Abstract: Spreading, dilution and mixing processes in the groundwater are influenced not only by the heterogeneous properties of the porous media but also by the boundary conditions. Although less studied than the heterogeneity of the soil matrix, highly transient boundary conditions can often occur in the field and can also enhance mixing in Darcy flows. In this work, we focus on surface water-groundwater interaction, in particular on rivers affected by hydropeaking, an artificial flow regime with sharp and frequent water level fluctuations resulting from the operation of hydropower plants. To study how hydropeaking can affect the groundwater flow field and thus mixing in the subsurface, we modeled a cross-section of the Adige Valley, in Italy, where two Alpine rivers, the Noce and the Adige, are differently affected by hydropeaking. We performed two-dimensional flow and transport simulations using a calibrated model, and investigated different scenarios, considering both sub-daily and seasonal fluctuations. We characterized the flow field applying different topological and kinematic indicators and show their relation to mixing processes in the subsurface. Our results show that hydropeaking and hence the management of hydropower plants have a major effect on groundwater solute transport.

DOI: https://doi.org/10.3850/IAHR-39WC252171192022763

Year: 2022