Description
At present, the water resources exploited amount to less than 1 m3/s, and are mainly concentrated in the most important peripheral sources of the massif (Centonia, Fusin Molin, Busoni and Acquasanta), and are part of the main aqueducts of Val di Sole, Val di Non, Piana Rotaliana, the Paganella plateau, the medium and high Sarca Valley.
In the face of a continuous increase in the demand for quality drinking water, the demands for agricultural (irrigation consortia) and industrial (artificial snowmaking, hydroelectric power stations) use of the Brenta Dolomite waters have also increased in recent years, and for some springs (e.g. Busoni), the concessions currently in place exceed the water capacity during many critical periods of the year, such as the winter lean months and the summer irrigation months.
In the past, several hydrogeological and geochemical studies have been carried out on the territory of the Brenta Dolomites, performed by the Tridentine Natural Science Museum, such as the study "Karst aquifers in Trentino" financed by the P.A.T. Environment Department between 1998 and 2001, and the research "Study on the non-reddening of Lake Tovel" financed by the P.A.T. Research Project Fund between 2001 and 2005. These studies, which focused on a limited part of the Brenta Dolomites territory such as the Grostè area and the Tovel Valley, although they can be considered the ideal starting point for the present research, are not sufficient for a complete knowledge of the entire hydrostructure.
The Geological Service of the P.A.T. has a particular interest in the study of the karst aquifers of the Brenta Dolomites, which represent one of the main sources of supply in the province, and therefore a strategic resource in the context of the growing demand for water both for drinking and for industrial and agricultural use.
The quantitative and qualitative knowledge of the hydropotable resources of the massif has both economic repercussions (optimisation of the water resources in the hydropotable, agricultural and industrial spheres), preventive environmental repercussions (identification of areas particularly at risk due to the vulnerability of the hydropotable karst aquifers), and scientific repercussions (hydrological balance of the entire massif, tools for the creation of hydrogeological and vulnerability maps, geochemical and isotopic studies, etc.). Moreover, the research provides the basis for outlining possible scenarios for the use of water resources in the light of the decrease in rainfall caused by the current climate warming that affects the Alpine arc in particular.
Objectives
The research was aimed at monitoring all hydrogeologically important points (both at source and along surface watercourses) in order to arrive at a complete and integrated continuous analysis and monitoring system. At the same time, a detailed programme of chemical-physical, isotopic and bacteriological analyses was carried out at different times of the hydrological year on the major sources that are captured or of possible future hydropotable use. The time horizon for the monitoring and analytical part was set at 24 months (two complete hydrological years), preceded by an initial phase of a few months (approximately 12) to get the hydrological monitoring network up and running and to set up the spring and meteoric water sampling points. In particular, the objectives set and then achieved can be summarised as follows:
O1. Quantification of flow rates and continuous monitoring of the main karst springs (captured and not) in the Brenta Dolomites for the purpose of a census of the main water resources.
O2. Quantification of flow rates and continuous monitoring of the main watercourses within the area of the Brenta Dolomites.
O3. Study of the heights and catchment areas of the main karst springs through the use of isotopic analyses and hydrogeological models that have made it possible to identify the main underground flow directions according to the different hydrostructures.
O4. A study of the vulnerability of the main karst aquifers and the quality of spring water through the identification of possible sources of both point and areal pollution, as well as chemical-physical and bacteriological analyses of the spring water during the different seasons, and according to the main meteorological events (snowmelt, major rainfall events, winter lean, etc.).
O5. Drawing up an overall hydrogeological balance of the entire massif by comparing: i) meteoric precipitation, ii) effective infiltration derived from geochemical and evapotranspiration models, iii) surface runoff measured at major watercourses, iv) underground runoff measured at major karst springs.
In particular, objectives O1, O2 and O5 are of primary importance in determining the hydro-potable potential of the massif as a function of the different water emergence levels and, therefore, in the possible rationalisation in the use of the water resource.
Objectives O3 and O4 are the natural qualitative complement to the research. They can provide operational tools for land use planning in medium and high mountain areas with high vulnerability, and are part of the U.A.P. forecast plan with a view to the study and knowledge of underground water tables.