Characterization of a carbonate groundwater system using a multitracing approach: an example from the mountain region “Pale di San Martino (Italy)”
2 Università degli Studi di Parma
P 1.6 in Hydrogeology of alpine regions
Carbonate aquifers, such as limestones and dolomites, are one of the main source of drinking water worldwide as it is estimated that 25% of the global population is supplied by karst water (Ford and Williams, 1989). Climatic changes, including significantly lower rainfall and higher temperatures are increasing the water stress and the need to study karst areas that have typically being rich of water, such as the Alpine regions. This study aims at characterizing the groundwater system of the “Pale di San Martino”, a mountain range located in the Italian eastern Alps, using a multitracing approach. In mountain and karsifed aquifers conventional hydrogeological methods often fail because of the highly unpredictable network of flow paths. Furthermore, accessibility issues during the winter months and the lack of observation wells or meteorological stations at high altitude, complicate the monitoring activities. In this framework, springs become an irreplaceable and indirect source of information on the groundwater flow because they integrate the signal of geological and hydrological processes over large spatial areas (Manga, 2001). Therefore, this study focuses on spring and it combines data deriving from existing databases with new field activities, which are still in progress. The field work started in July 2014 and it consisted in the following topics:
- General assessment of regional geology and hydrogeology including the identification of the springs locaion on the field;
- In situ measurements of several physico-chemical parameters of the spring water (Ph, Ec, ORP, Temperature);
- Seasonal spring sampling for geochemical and stable isotopes analyses and monthly rainfall sampling;
- Progressive discharge measurements along the main streambeds to estimate the total volume of groundwater discharging from the massif and to identify linear springs;
- A water tracing test with fluorescent dye performed on August 2015 (another test is planned for spring 2016).
Groundwater hydrogeological and hydrogeochemical data were used to quantify and trace water fluxes. In addition, stable isotope tracer methods and fluorescent dye test enabled the refinement of the conceptual model of the groundwater flow and provided indirect information about flow direction and velocity. All the data were combined in order to understand groundwater flow mechanisms and to constrain flow paths in the karst and fracture-controlled groundwater system.
FORD, D., AND WILLIAMS, P.W., (1989): Karst geomorphology and hydrology, London, Unwin Hyman, 601 p.
MANGA, M. (2001): Using springs to understand groundwater flow and active geologic processes, Annual Reviews of Earth and Planetary Sciences, vol. 29, 203-230.