The role of alpine valley fill deposits for groundwater storage (Dolomites, Italy) (original) (raw)
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The Kanin massif is an important trans-boundary aquifer, which stretches between Slovenia and Italy. The groundwater is only partially exploited, mainly for water supply, but the aquifer exhibits great potential for future exploitation. Since no consistent regional overview of the hydrogeological functioning of the Kanin massif was available, the decision was made to perform a study of this area, using a pragmatic approach based on 3D geological and hydrogeological modelling. The so-called KARSYS approach was applied, with the aim of characterizing the groundwater reserves within this karst massif and of locating the main drainage axes that carry groundwater from the recharge areas to the respective springs. Delineation of the catchment areas of the corresponding springs was carried out, and some new explanations were obtained, especially with regard to the Možnica spring, which is located in Slovenia and forms a potential source of drinking water. It was found that this spring’s catchment area extends as far as the Italian ski resort of Sella Nevea. The conceptual model also provides a possible explanation about the underground drainage towards the Boka spring and waterfall, which has been a challenge for decades. This new explanation is based on the existence of a perched groundwater body that feeds the Boka spring via a system of conduits. Despite some limitations, the results, which consist of a visualization of the underground drainage and groundwater storage within the Kanin massif, can be used as a basis for planning the sustainable management of karst waters in the studied area.
Hydrogeology Journal
Garber Schlag (Q-GS) is one of the major springs of the Karwendel Mountains, Tyrol, Austria. This spring has a unique runoff pattern that is mainly controlled by the tectonic setting. The main aquifer is a moderately karstified and jointed limestone of the Wetterstein Formation that is underlain by nonkarstified limestone of the Reifling Formation, which acts as an aquitard. The aquifer and aquitard of the catchment of spring Q-GS form a large anticline that is bound by a major fault (aquitard) to the north. Discharge of this spring shows strong seasonal variations with three recharge origins, based on δ18O and electrical conductivity values. A clear seasonal trend is observed, caused by the continuously changing portions of water derived from snowmelt, rainfall and groundwater. At the onset of the snowmelt period in May, the discharge is composed mainly of groundwater. During the maximum snowmelt period, the water is dominantly composed of water derived from snowmelt and subordinat...
Hydrology and Earth System Sciences Discussions, 2014
The frequency and intensity of extreme hydrological events in Alpine regions is projected to increase with climate change. The goal of this study is to better understand the functioning of aquifers composed of complex alluvial and rockfall deposits in Alpine valleys and to quantify the role of these natural storage spaces in flood attenuation and baseflow maintenance. Geomorphological and hydrogeological mapping, tracer tests, and continuous flow measurements were conducted in the Reintal (German Alps), where runoff from a karst spring infiltrates a series of postglacial alluvial/rockfall aquifers. During high-flow conditions, groundwater velocities of 30 m h −1 were determined along 500 m; hydrograph analyses revealed short lag times (5 h) between discharge peaks upstream and downstream from the aquifer series; the maximum discharge ratio downstream (22) and the peak recession coefficient (0.196 d −1 ) are low compared with other Alpine catchments. During low-flow conditions, the underground flow path length increased to 2 km and groundwater velocities decreased to 13 m h −1 . Downstream hydrographs revealed a delayed discharge response after 101 h and peaks damped by a factor of 1.5. These results indicate that alluvial/rockfall aquifers might play an important role in the flow regime and attenuation of floods in Alpine regions.
Science of The Total Environment, 2020
Time series of environmental tracers (groundwater stable isotope composition, electrical conductivity and temperature) and concentration breakthrough curves of artificial tracers (uranine, eosine, amino-G and naphtionate) have been analyzed to characterize fast preferential and slow matrix in-transit recharge flows in the Paleocene-Eocene limestone aquifer of the Ordesa and Monte Perdido National Park, an alpine karst system drained by a water table cave, a rare hydrological feature in high mountain karst systems with similar characteristics. Snowmelt favors the areal recharge of the system. This process is reflected in the large proportion of groundwater flowing through the connected porosity structure of the karst aquifer, which amounts the 75% of the total system water discharge. From the perspective of water resources recovery, the water capacity of the fissured-porous zone (matrix) represents 99% of the total karst system storage. The volume associated to the karst conduits is very small. The estimated mean travel times are 9
Austrian Journal of Earth Sciences, 2016
During the construction of the Brenner Base Tunnel (BBT), on the Austrian project side about 12 million m³ of tunnel excavation material have to be disposed of in landfills, since this material cannot be used as aggregate. Therefore, the Padaster Valley, a side valley of the Wipp Valley, will be filled in with nearly 8 million m³ excavation material and with a maximum filling height of about 78 meters. Due to the size of the disposal site and the settlements situated immediately downstream, the geological underground conditions and in particular the hydraulic behaviour of the groundwater body play an important role for the planning and the construction of the disposal site. Based on field data, borehole and pit logging and sampling, geophysical investigations and lab data, a conceptual geological model was established for the complex sediment content of the quaternary infill of the Padaster Valley. Combining above data and the established conceptual geological model, Multiple Point Geostatical Simulation (MPS) was used to derive a quantitative and realistic volumetric representation of the sedimentary infill. It is the basis for the conceptual hydro geological model of the Padaster Valley. For the design of the groundwater monitoring network of the complex site the elaboration of a hydrogeological conceptual model in the early project phase was essential. We assume several flow systems in the quaternary infill lacking thick or continuous layers in form of aquitards or aquicludes; most of the hydraulic impact is due to fine-grained sediment lenses and layers within the soft rock body. The hydrogeological conceptual model with implications to the groundwater monitoring network in the alpine valley site is discussed. The results of this study shall contribute to a better comprehension of the complex geological conditions and hydrogeological processes in alpine side valleys. Im Zuge der Errichtung des Brenner Basistunnels (BBT) müssen auf der österreichischen Projektseite ca. 12 Millionen m³ an Ausbruchsmaterial deponiert werden, da das Material für die Nutzung als Zuschlagstoff nicht geeignet ist. Diesbezüglich wird ein Seiten tal des Wipptales, das Padastertal, mit 8 Millionen m³ Material und einer maximalen Schütthöhe von ca. 78 m aufgefüllt. Aufgrund der Größe der Deponie, aber auch der unmittelbar talseitig gelegenen Siedlung, spielen sowohl für die Planung als auch für die Ausführung der Deponie der geologische Untergrund und insbesondere das hydraulische Verhalten des Grundwasserkörpers eine wesentliche Rolle. Auf Grundlage von im Feld erhobenen Daten, Bohrungen und Schürfen, sowie geophysikalischen Er kundungen und Laborversuchen wurde ein konzeptionelles geologisches Modell für den komplexen Sedimentkörper der quartären Talfüllung des Padastertals erstellt. Durch Kombination von Erkundungsergebnissen und geologischem Modell, wurde mittels Multiple Point Geostatical Simulation (MPS) eine quantitative und realistische Darstellung der sedimentären Talfüllung erstellt. Das MPS Modell stellt dabei die Basis für das konzeptionelle hydrogeologische Modell des Padastertals dar. Zur Errichtung eines Grundwassermessstellennetztes für die komplexe Baustelle war die Ausarbeitung eines hydrogeologischen Modells in einer frühen Projektphase notwendig. Es zeigt sich, dass sich im Lockergesteinskörper verschiedene Fließsysteme eingestellt haben, obwohl augenscheinliche mächtige oder durchgehende Trennschichten in Form von Aquitards oder Aquicludes fehlen. Diesbezüglich wird auf die hydraulische Wirkung von feinkörnigen Linsen und Lagen im Lockergesteinskörper eingegangen. Weiters wird das hydrogeologische konzeptionelle Modell mit Auswirkungen auf das Grundwassermessstellennetz in dem alpinen Seitental diskutiert. Die Untersuchungen und Ergebnisse sind ein Beitrag zum Verständnis der komplexen hydrogeologischen Prozesse in alpinen Seitentälern.
2002
Groundwater from karst aquifers is among the most important drinking water resource for humanity. About one quarter of the global population is supplied by karst waters. In some alpine countries, karst water contributes 50 % to the total drinking water supply and some cities in the alpine region are almost totally dependent on karst waters. At the same time, karst aquifers are particularly vulnerable to contamination. Contaminants can easily enter the underground and are transported rapidly over large distances in the aquifer. Processes of contaminant retardation and attenuation often do not work effectively in karst systems. Therefore, karst groundwater needs special protection. A detailed knowledge of the hydrogeology of karst systems is the precondition for the development of sustainable protection schemes. Any kind of generalisation is problematic and each karst system has to be investigated individually. This is particularly important for alpine karst systems which comprise a large variety of geologic, hydrologic, climatic and topographic settings.
Active rock glaciers as shallow groundwater reservoirs, Austrian Alps
Grundwasser
Rock glaciers are the most prominent landforms of alpine permafrost and comprise complex shallow aquifer systems in (high) alpine catchments. Recession analyses of groundwater discharge of four active rock glaciers that contain permafrost ground ice show that they have a base flow component of the order of a few liters per second, similar to that of a relict rock glacier in which permafrost ground ice is absent. This is related to an unfrozen (fine-grained) base layer with a thickness of about 10 m. Based on a threshold analysis of precipitation events and event water discharge, depressions atop the bedrock or the permafrost table seem to play only a minor role in storing groundwater. This important finding has rarely been documented, but is highly relevant for optimal groundwater resources management in sensitive (high) alpine catchments and ecosystems. All the rock glaciers analyzed here are located in the Austrian Alps and represent the nationwide sites where suitable discharge d...
Hydrological Processes, 2012
Regional groundwater flow in high mountainous terrain is governed by a multitude of factors such as geology, topography, recharge conditions, structural elements such as fracturation and regional fault zones as well as man-made underground structures. By means of a numerical groundwater flow model, we consider the impact of deep underground tunnels and of an idealized major fault zone on the groundwater flow systems within the fractured Rotondo granite. The position of the free groundwater table as response to the above subsurface structures and, in particular, with regard to the influence of spatial distributed groundwater recharge rates is addressed. The model results show significant unsaturated zones below the mountain ridges in the study area with a thickness of up to several hundred metres. The subsurface galleries are shown to have a strong effect on the head distribution in the model domain, causing locally a reversal of natural head gradients. With respect to the position of the catchment areas to the tunnel and the corresponding type of recharge source for the tunnel inflows (i.e. glaciers or recent precipitation), as well as water table elevation, the influence of spatial distributed recharge rates is compared to uniform recharge rates. Water table elevations below the well exposed high-relief mountain ridges are observed to be more sensitive to changes in groundwater recharge rates and permeability than below ridges with less topographic relief. In the conceptual framework of the numerical simulations, the model fault zone has less influence on the groundwater table position, but more importantly acts as fast flow path for recharge from glaciated areas towards the subsurface galleries. This is in agreement with a previous study, where the imprint of glacial recharge was observed in the environmental isotope composition of groundwater sampled in the subsurface galleries.
Karst morphology and groundwater vulnerability of high alpine karst plateaus
Environmental Earth Sciences, 2009
High alpine karst plateaus are recharge areas for major drinking water resources in the Alps and many other regions. Well-established methods for the vulnerability mapping of groundwater to contamination have not been applied to such areas yet. The paper characterises this karst type and shows that two common vulnerability assessment methods (COP and PI) classify most of the areas with high vulnerability classes. In the test site on the Hochschwab plateau (Northern Calcareous Alps, Austria), overlying layers are mostly absent, not protective or even enhance point recharge, where they have aquiclude character. The COP method classifies 82% of the area as highly or extremely vulnerable. The resulting maps are reasonable, but do not differentiate vulnerabilities to the extent that the results can be used for protective measures. An extension for the upper end of the vulnerability scale is presented that allows identifying ultra vulnerable areas. The proposed enhancement of the conventional approach points out that infiltration conditions are of key importance for vulnerability. The method accounts for karst genetical and hydrologic processes using qualitative and quantitative properties of karst depressions and sinking streams including parameters calculated from digital elevations models. The method is tested on the Hochschwab plateau where 1.7% of the area is delineated as ultra vulnerable. This differentiation could not be reached by the COP and PI methods. The resulting vulnerability map highlights spots of maximum vulnerability and the combination with a hazard map enables protective measures for a manageable area and number of sites.