From Lithological Modelling to Groundwater Modelling: A Case Study in the Tiber River Alluvial Valley

This study presents the results of a research project financed by the Lazio Regional Government. The research focused on defining an integrated model of recent alluvial deposits in the Tiber River. To achieve this objective, geological boreholes were made to monitor the aquifer and in situ and laboratory tests were carried out. The data obtained were used to detail stratigraphic aspects and improve the comprehension of water circulation beneath the recent alluvial deposits of the Tiber River in the urban area of Rome, between the Ponte Milvio bridge and the Tiber Island. The stratigraphic intervals recognised in the boreholes were parameterised based on their litho-technical characteristics. The new data acquired, and integrated with existing data in the database of Institute of Environmental Geology and Geoengineering of the Italian National Research Council, made it possible to produce a three-dimensional model of the lithologies in the study area. The model of the subsoil, simplified for applied reasons, was described in hydrostratigraphic terms: three different lithotypes were subjected to piezometric levels monitoring. Finally, the research generated a numerical hydrological model in a steady state. In general, this study demonstrates how a numerical hydrogeological model calibrated by piezometric monitoring data can support the construction of a geological model, discarding or confirming certain hypotheses and suggesting other means of reconstructing sedimentary bodies.

General 1-D hydrogeological model for temporal near-surface loess saturation assessment for the needs of radon potential mapping

Radon gas has high mobility and is driven by advection and diffusion with the soil gas throughout connected and water-unsaturated pores and/or cracks in permeable rocks and soils. Hence the radon potential of the area could be dependent on not only geology as a constant source of radon but also from the changes of the saturation state of the ground. The loess complex, characterized by its permeability and usual state of unsaturation, covers 10% of the Bulgarian territory. The study deals with the principles of unsaturated domain modeling. An attempt of generic vertical infiltration model coinciding with the most upper part of loess vadose zone was performed.

A Conceptual Socio-Hydrogeological Model Applied to Sustainable Water Management. Case Study of the Valdivia River Basin, Southwestern Ecuador

The scientific community has a growing interest in understanding the interaction of the human-water system in water resource models. In Santa Elena (Ecuador), Valdivia, San Pedro, Sinchal, Barcelona and Carrizal communities are located in a semi-arid area, making the water supply a critical problem for local communities. In addition to the climatic conditions of the sector, the main problem is the weak participation in the integral management of the groundwater resource by the stakeholders involved. Specifically, there is evidence of a lack of ancestral-technical knowledge in management strategies and the fact that the demand for water for agriculture, tourism, and their basic needs exceed the sustainable supply capacity. The present study assesses the natural and anthropic conditions of the middle and lower basin of the Valdivia river through a socio-hydrogeological conceptual model of the river-aquifer system to develop productive activities in an environment of sustainability. The study methodology consists of four phases: i) river basin data analysis, ii) hydrogeological studies, iii) application of the Participatory Action Research (PAR) and Strengths-Weaknesses-Opportunities-Threats (SWOT) analysis, and iv) conceptual model of the river-aquifer system. The results show that the socio-hydrogeological model of the Valdivia River basin has four systems: hydrogeological, ecological, economic, and social. In addition, the research detected problems present in the systems, such as droughts due to the influence of natural phenomena, aquifer overexploitation, lack of aquifer sustainability techniques, weak management and control of water resources, contamination of water sources and a lack of support from government agencies. The systems identified allow JAAPR-Valdivia to manage strategies to solve the problems detected in search of the sustainability of water resources.

Hydrogeological modelling of Olkaria domes geothermal field to predict ground subsidence

Ground subsidence studies have been done on Olkaria geothermal field conventionally by comparing levels on benchmarks over years. Interferometric synthetic aperture radar (InSAR) systems have also been used to map surface deformation of small spatial extent. For the prediction of future dynamics of land subsidence in Olkaria due to geothermal resource exploitation, a hydrogeological conceptual model has been developed. In this model, hydrologic geothermal fluid properties are analysed and a relationship between the reservoir and geology of the wells established, subsidence is computed numerically. The model takes into account the hydrogeological condition of Olkaria geothermal field. Hydrological reservoir parameters are computed from well testing data. The study considers the Injectivity indices of the various wells under study as pre-computational indicator of the expected subsidence extents. Both two- and three-dimensional geological cross-sections are modelled with the rockworks software by inputting stratigraphic data for Olkaria domes. Geological simulations are used to study subsidence by assigning the ground formation with virtual material that deformed according to some essential relations in Rockworks computer software. Production zones are determined by a comparison between the well properties and corresponding well geology. Subsidence is then computed by the Tezarghi’s modified equation. Cumulative subsidence figures from the computation are in the range of 0.095-0.537m, without any reinjection. Computed values are then mapped in ArcGIS to develop a representative subsidence map. By application of these modelling and numerical computation methods, ground subsidence was effectively predicted using the five selected wells in Olkaria domes field. The hydrogeological model developed, and mapping is an important tool in the planning and development of a reinjection schedule and in subsidence mitigation. Subsidence prediction also is important in design of infrastructure which will be strong enough to resist the forces caused by subsidence.

From Lithological Modelling to Groundwater Modelling: A Case Study in the Tiber River Alluvial Valley

This study presents the results of a research project financed by the Lazio Regional Government. The research focused on defining an integrated model of recent alluvial deposits in the Tiber River. To achieve this objective, geological boreholes were made to monitor the aquifer and in situ and laboratory tests carried out. The data obtained was used to detail stratigraphic aspects and improve the comprehension of water circulation beneath the recent alluvial deposits of the Tiber River in the urban area of Rome, between the Ponte Milvio bridge and the Tiber Island. The stratigraphic intervals recognised in the boreholes were parameterised based on their litho-technical characteristics. The new data acquired, and integrated with existing data in the CNR IGAG database, made it possible to produce a three-dimensional model of the lithologies in the study area.The model of the subsoil, simplified for applied reasons, was described in hy-drostratigraphic terms: three different lithotypes were subjected to piezometric levels monitor-ing. Finally, the research generated a numerical hydrological level in a stationary regime. In general, this study demonstrates how a numerical hydrogeological model calibrated by piezo-metric monitoring data can support the construction of a geological model, discarding or con-firming certain hypotheses and suggesting other means of reconstructing sedimentary bodies.

ASSESSMENT OF CHANGES IN THE HYDROGEOLOGICAL CONDITIONS CAUSED BY WET-BASED CONSERVATION OF THE STYLSKYI QUARRY OPERATED BY “DOKUCHAEVSK FLUX AND DOLOMITE COMPLEX” PJSC USING MATHEMATICAL MODELLING

Extraction of minerals significantly affects the hydrogeological conditions of the environment. Active development of mining operations in the Donbas region determined the dominant influence of technogenic changes in geological environment on the formation of modern ecological conditions in the region. This applies not only to coal mining but also raw materials extraction (dolomites, limestone) for metallurgical plants mostly by quarrying. Recently, a significant environmental problem in the region has been the mines and quarries closure, envisaged by the program for restructuring the coal industry of Ukraine. Closure of mines or quarries through wet-based conservation is the least financially expensive, although it significantly increases the technogenic load on the natural environment. The object of research involved groundwater and surface water within the area of the Stylskyi and Skhidnyi (Vostochnyi) quarries of the “Dokuchaevsk flux-dolomite complex” PJSC, as well as Kipucha Krynytsa and Shevchenkivskyi water intake structures. The goal of research was to forecast changes in the hydrogeological conditions under the influence of wet-based conservation of the Stylskyi quarry. To achieve this goal, hydrogeological methods, mathematical modelling, and expert assessments were used. Consequently, a hydrogeological model of the research area was created, its functional correspondence to the natural-anthropogenic conditions was confirmed, and calculation hydrogeological parameters were specified. As a result, the forecast of changes in the hydrogeological conditions under the influence of wet-based conservation of the Stylskyi quarry was made. In particular, the following issues were determined: the dynamics of quarry flooding; the influence of this process on changes in water inflows to the Skhidnyi (Vostochnyi) quarry, Kipucha Krynytsa and Shevchenkivskyi water intake structures; possible flooding of settlements and swamping of the research area; changes in chemical composition and groundwater salinity; time of quarry draining at various intensity of water outflow to resume mineral production in case of need. We would like to emphasize that the forecasts made should be used when designing partial or full flooding of the Stylskyi quarry.

Evaluation of Groundwater Resources in Minor Plio-Pleistocene Arenaceous Aquifers in Central Italy

The hilly landscape of the Periadric area in Central Italy is characterized by mainly marly–clayey foredeep basin deposits (Plio–Pleistocene age). These lithotypes are generally considered aquicludes, if compared with the regional limestone aquifers of Apennines. However, a coarsening upward trend characterizes the upper portion of this stratigraphic sequence, with arenaceous deposits and even conglomerates on the top. From a geomorphological viewpoint, the areas with coarser outcrops show a flat shape and sub-vertical slopes, like boundaries. At the base of these scarps, springs can be found at the interface between coarse and fine deposits, whereas these arenaceous bodies are actual aquifers. Until now, the hydrodynamics and hydrochemical features of this kind of aquifer have not been investigated deeply, because they have always been considered a worthy water resource. However, they could play a crucial role in integrated water management, especially to cope with climate changes and drought periods. Considering these, the main purpose of this study was to investigate from a hydrogeological point of view and to assess the groundwater quantity and quality. Five examples throughout the Abruzzo region were considered. For evaluation and comparisons between water resources, the water volume that infiltrates yearly at each squared kilometer of an aquifer (Mm3/y/km2) was applied. This value was calculated through three different approaches to provide a recharge estimation for this kind of aquifer that is as exhaustive and representative as possible. The results allowed us to characterize the hydrogeological model and to quantify the resources between 0.1 and 0.16 Mm3/y/km2, to be suitable for multi–purpose utilization.

3D Modelling of a Hydrothermal System in a Densely Populated Urban Area – the Alfama Springs Case-Study (Lisbon, Portugal)

In the XIX th century, the Alfama thermal and non-thermal springs were qualified as “mineral water” by the governmental authorities. But after a few years of legal usage in balneotherapy, all of them knew a constant and progressive definitive decay, and the last balneotherapic facility was abandoned and sealed more than 40 years ago. Despite their significant influence in Lisbon life along the History, their exact location is now only approximate. Nowadays, they are all buried below the city buildings, squares and streets. Since some of the Alfama springs reached temperatures up to 34 °C, groundwater from these springs can be used in a new modern spa or in district heating facilities in the heart of the city of Lisbon, if adequately recovered. But priorly, to carry out this task, a global understanding of the conceptual hydrogeological model is needed. However, the springs are located in a densely urbanized and touristic area, where geological outcrops are no longer visible and old springs’ location is unknown; therefore, a review of geological and hydrogeological data and geotechnical reports was carried out to plan further research works. Adding to this exhaustive bibliographic review and data integration, new seismic reflection data were acquired, and brought some new insights on the groundwater circulation system. All these data interpretations contributed significantly to achieve a better knowledge on the main and secondary faults that control the occurrence of Alfama springs and framed them into the complex regional tectonic framework. The entire set of historical hydrogeological data, geotechnical information, and newly acquired data lead to a reasonably accurate and data supported 3D geological and hydrogeological conceptual model of the deep groundwater flow circuit. This paper describes the research work that led to the conception of the local and complex 3D hydrogeological model of the Alfama springs system. With this 3D model, the best location for a dipped well can now be envisaged, keeping in mind the narrow local urban constraints, possible future users, and stakeholders.