A double scale methodology to investigate flow in karst fractured media via numerical analysis. The Cassino plain case study (Central Apennine, Italy)

A methodology to evaluate the hydraulic conductivity of the karstmedia at a regional scale has been proposed, combining pumping tests and the hydrostructural approach, evaluating the hydraulic conductivity of fractured rocks at the block scale. Obtaining hydraulic conductivity values, calibrated at a regional scale, a numerical flow model of the Cassino area has been developed, to validate the methodology and investigate the ambiguity, related to a nonunique hydrogeological conceptual model. The Cassino plain is an intermontane basin with outstanding groundwater resources.The plain is surrounded by karst hydrostructures that feed the Gari Springs and Peccia Springs. Since the 1970s, the study area was the object of detailed investigations with an exceptional density of water-wells and piezometers, representing one of the most important karst study-sites in central-southern Italy. Application of the proposed methodology investigates the hydraulic conductivity tensor at local and regional scales, reawakening geological and hydrogeological issues of a crucial area and tackling the limits of the continuum modelling in karst medi

The geology and hydrogeology of the Cassino plain (central Apennines, Italy). Redefining the regional groundwater balance

Cassino plain is a Quaternary intermontane basin of the central-southern Apennines, Italy. The plain has outstanding groundwater resources (total discharge of 23,000 L/s), thanks to the huge karst basins that surround the area. The area has been involved in many hydrogeological interests since the 1970s due to the economic importance and construction of the Western Campania Aqueduct for the water supply of Naples city and its hinterland. Despite its importance, the area lacks a common accepted hydrogeological conceptual model due to the complex geological setting. Two contrasting conceptual models already exist in the literature, with the first model based on a quantitative hydrogeological approach and the second on fieldwork. Through a literature analysis and further detailed field surveys, a new conceptual model is presented, acknowledging the thrust tectonics of the Apennine chain. The model unveils the most important hydrogeological issues of the area, serving as a useful tool for groundwater management, as well as for considering the changing anthropic and climate scenarios. In particular, the study redefines the hydrostructure extents and the groundwater flowpaths, characterizing the main water resources as Gari and Peccia springs

Hydrogeological insights and modelling for sustainable use of a stressed carbonate aquifer in the Mediterranean area. From passive withdrawals to active management

Study area: Venafro Mts., southern-central Italy, Mediterranean basin. Study focus: Via a collection of geological and hydrogeological data, a flow conceptual model of a carbonate aquifer has been coupled with a numerical model via MODFLOW code and Unsaturated Zone Flow (UZF) package in steady state and transient conditions. Simulation is further implemented with different management scenarios, for facing possible emergencies due to recharge decrease, also simulating a drastic water abstraction cut-off. New hydrological insights for the region: Carbonate fractured aquifers are a strategic water resource in the whole Mediterranean area, supplying major metropolitan areas. Despite these huge extensions, such groundwater systems are threatened by increasing drought occurrence and significant human water abstraction. A characterization of a carbonate fractured aquifer (370 km2) located in central-southern Italy has been performed. Venafro Mts. Aquifer (VMA) hosts a strategic resource for the Western Campania Waterworks (WCW) that supplies the populous metropolitan area of Naples, with 3.8 million inhabitants. VMA shows a slow response, with recovery time estimated at the decennial scale, testifying its limited resilience to natural and human pressures. A shift is proposed from passive management to a more comprehensive concept of smart-water monitoring, applied not only to waterworks and pipelines, but also to groundwater resources in the environment

Movements detection of deep seated gravitational slope deformations by means of InSAR data and photogeological interpretation: northern Sicily case study

We investigated the northern-central portion of Sicily region (southern Italy) using aerial photographs and Synthetic Aperture Radar (SAR) data obtained by ERS1 and ERS2 satellites. This area shows a geological-structural setting generated by the tectonic superposition of Apenninic-Maghrebian carbonatic structures on terrigenous deposits. Such a structural setting favoured the development of large-scale gravity driven phenomena (known in the geological literature as deep-seated gravitational slope deformations) that are mostly responsible for the landscape evolution of the whole area. Morphological evidences such as landslides, sacking or rock-flow, lateral spread and block slide can be detected from photogeological analysis. In order to understand the temporal behaviour and spatial distribution of such deformations we applied the interferometric SAR (InSAR) technique. Interferograms show fringe patterns spatially coinciding with some of the large-scale gravitative phenomena previously identified by means of aerialphoto analysis. The comparison between photogeological data and InSAR results allows delimiting the active sectors in the study area

A macroscale hydrogeological numerical model of the Suio hydrothermal system (Central Italy)

The complex behaviour of the Suio hydrothermal system (central Italy) and its potential exploitation as a renewable energy source are still unclear. To quantitatively evaluate the geothermal resource, the Suio hydrothermal system has been investigated with a hydrogeological numerical model that couples fluid flow, thermal convection, and transport of diluted species inside a hybrid continuum-discrete medium. The numerical model, calibrated and validated with available and new experimental data, unveiled the complex behaviour of the hydrothermal system. The normal tectonic displacements, the fracturing of the karst hydrostructure, and the aquitard distribution strongly influence the hydrothermal basin. In particular, a dual fluid circulation, sustained by steady-state thermal and pressure gradients, modulates the hydrothermalism at the several springs and wells. The presence of a medium to a low-temperature reservoir allows for potential exploitation of the geothermal resource

Subsidence Detected by Multi-Pass Differential SAR Interferometry in the Cassino Plain (Central Italy): Joint Effect of Geological and Anthropogenic Factors?

In the present work, the Differential SAR Interferometry (DInSAR) technique has been applied to study the surface movements affecting the sedimentary basin of Cassino municipality. Two datasets of SAR images, provided by ERS 1-2 and Envisat missions, have been acquired from 1992 to 2010. Such datasets have been processed independently each other and with different techniques nevertheless providing compatible results. DInSAR data show a subsidence rate mostly located in the northeast side of the city, with a subsidence rate decreasing from about 5–6 mm/yr in the period 1992–2000 to about 1–2 mm/yr between 2004 and 2010, highlighting a progressive reduction of the phenomenon. Based on interferometric results and geological/geotechnical observations, the explanation of the detected movements allows to confirm the anthropogenic (surface effect due to building construction) and geological causes (thickness and characteristics of the compressible stratum

The relationship between seismic deformation and deep seated gravitational

This paper re-evaluates the origin of some peculiar patterns of ground deformation observed by space geodetic techniques during the two earthquakes of September 26th of the Colfiorito seismic sequence. The surface displacement field due to the fault dislocation, as modeled with the classic Okada elastic formulations, shows some areas with high residuals which cannot be attributed to unsimulated model complexities. The latter was investigated using geomorphological analysis, by recognising the geologic evidence of deep seated gravitational slope deformations (DSGSD) of the block-slide type. The shape and direction of the co-seismic ground displacement observed in these areas are correlated with the expected pattern of movement produced by the reactivation of the identified DSGSD. At least a few centimetres of negative Line of Sight ground displacement was determined for the Costa Picchio, Mt. Pennino, and Mt. Prefoglio areas. A considerable horizontal component of movement in the Costa Picchio DSGSD is evident from a qualitative analysis of ascending and descending interferograms. The timing of the geodetic data indicates that the ground movement occurred during the seismic shaking, and that it did not progress appreciably during the following months. In this work it has been verified the seismic triggering of DSGSD previously hypothesized by many authors. A further implication is that in the assessment of DSGSD hazard it is necessary to consider the seismic input as an important cause of acceleration of the deformation rates