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APPLICAZIONE DI UNA METODOLOGIA INNOVATIVA PER LA VALUTAZIONE DEL PERICOLO DI CONTAMINAZIONE DELLE RISORSE IDRICHE SOTTERRANEE
No full textKruger national park. Geological and hydrogeological assessment to save the integrity of a protected area
No full textThe purpose of the present study, included in the research project SECOSUD Phase II, called “Conservation and equitable use of biological diversity in the SADC region (Southern African Development Community) [1], is to describe the existing baseline situation in term of geological and hydrogeological conditions of the Kruger National Park, providing a starting point for understanding the water resources status quo, potential hydrogeological issues and concerns to assure a sound and correct water resources management in a so sensitive and complex area [2]. Kruger National Park is South Africa's largest and second oldest safari park, spanning over 19 455 square kilometres across both the Limpopo and the Mpumalanga provinces, with an altitude between 300 and 500 metres above sea level. Kruger Park is a summer rainfall area, include in the Great Limpopo Transfrontier Park. The prominent climate is subtropical, with a rainy season in summer and a dry winter season. Because of its vastity, it naturally has an incredible diversity of its life forms. The link between biodiversity and ecosystems are ruled by sensitive balances. There is growing evidence that groundwater has an essential and vital role safeguarding the integrity of floral and faunal specimens and their ecosystems, and consequently hydrogeological and geological assessment inside the focus area represent powerful and strategic tools to know quantitative and qualitative aspects of water resources, aspects of groundwater flow and geology of groundwater occurrence. The first phase of the following methodological approach was to gather regional and local geological data which allowed to define a detailed geological map of Kruger National Park, pointing out the main geological units outcropping. The geological map has been elaborated using software Quantum Gis, taking into account the lithostratigraphic units derived from the Soil and Terrain database (SOTER) for Southern Africa occurring in the area of concern. Hydrogeological assessment has been developed implementing the groundwater levels data, from monitoring piezometers in the park, recorded between 2007 and 2012. These data has been correlated with the conditions of outcropping rocks and the infiltration properties of lithostratigraphic formations. This evaluation allowed to subdivide Kruger Park area on the basis of the geological units encountered to identify formations rocks with similar hydrogeological properties and main groundwater recharge areas. The intent of this research is to increase attention and focus on the local hydrogeological and geological conditions, because they represent an excellent instrument of scientific knowledge to understand which is the priority in a sustainable management of the water resources to keep the ecological integrity protected areas
Magnesium and groundwater flow relationship in karst aquifers: a tool for exploitation management of springs // La relazione tra magnesio e circolazione delle acque sotterranee in acquiferi carsici: uno strumento per la gestione della captazione dalle sorgenti
Full text linkKarst aquifers are characterized by different types of groundwater flow, related to different types of permeability due to the simultaneous presence of matrix, fractures and conduits. The presence of a well-developed karst conduit system leads to a rapid circulation of groundwater within the aquifer and a pulse-type response of the spring flow to the rainfall inputs, with a potential fast transport of contaminants from the hydrogeological basin surface to the discharge zones. Supported by hydro chemical analyses of spring water samples and single discharge measurements, it was possible to develop specific mass balance models, correlating ion content to spring flowrates. Specifically, Mg2+ content revealed a reliable application for spring baseflow separation in karst settings. Once the local model has been set, its conservative behaviour, in mostly limestone-dominant aquifers, allows using Mg2+ as a natural tracer of groundwater flow, distinguishing conduit flow (overflow) and diffuse flow (baseflow) occurrence in the spring outlet, without additional discharge measurements. In karst settings, the difficulty in continuously monitoring the spring discharge values makes this application interesting for exploitation management. This study shows the results obtained for two springs located in Central Italy, confirming that monitoring groundwater quality in karst environments is often the key for successfully characterizing springs and assessing the total yield when direct measurements are not available
Hydraulic Analysis of the Suitable Construction Solutions in the Middle Tiber River
No full textThe hydraulic safety of the historic centre of Rome is guaranteed by preventing flooding events of the Tiber River by the embankment walls called “Muraglioni”. For this reason, it is necessary to maintain the flood attenu ation capacity ensured by the flooding of the floodplain areas upstream of the city. The urban evelopments of these areas are sustainable only by hydraulics engineering infrastructures aimed at controlling the flood in the floodplain areas in case of 100-year and 200-year return time meteoric and hydraulic extreme events. This work presents the engineering solutions and the results of the hydraulics analysis carried out on making compatible road infrastructures and flood protection infrastructures in the territory, such as river embankments and detention basins. The Tiber River has been studied to respect this target, setting up a one-dimensional numerical model using HEC-RAS and a two-dimensional model using SMS and BAS.E.MENT software. The numerical simu lations of floods have been carried out with a 200-year return time in the several phases of construction of the infrastructures in the area. The analysis identified the most suitable design choices, saving the neighbouring Rome metropolitan area from increasing hydraulic risks
Recent drought effects on bracciano lake water availability
No full textDrought events are currently increasing in frequency and intensity all over the world as effect of climate change. One of the most related environmental issue is water resource scarcity, which is now becoming an emergency also for several industrialized countries in the Mediterranean area. In the summer of 2017, all Italian territory suffered from an extreme drought event that caused huge depletions of both groundwater and surface water availability. In particular, Bracciano Lake, which is one of the largest surface water resource of Central Italy, showed the largest water level drop in 50 years of observation, with a critic impact on the Lake’s ecological system. This event highlighted once again the key-role of water shortage analysis, whose main goal is studying the relationship between rainfall deficit and water resources availability. Moreover, their long-term trends need to be studied in order to find sustainable solutions for the increasing water demand of the population. In particular, in this paper, data related to time series of about 60 years have been analyzed with the aim of finding highly significant relationships between Bracciano Lake level drops at different time scales, and the SPI (Standard Precipitation Index), which is currently the most widely used hydrological drought indicator. This study aims to demonstrate that specific drought indices may be useful tools for water system management
Hydraulic conductivity estimation using low-flow purging data elaboration in contaminated sites
Full text linkHydrogeological characterization is required when investigating contaminated sites, and hydraulic conductivity is an important parameter that needs to be estimated. Before groundwater sampling, well water level values are measured during low-flow purging to check the correct driving of the activity. However, these data are generally considered only as an indicator of an adequate well purging. In this paper, water levels and purging flow rates were considered to estimate hydraulic conductivity values in an alluvial aquifer, and the obtained results were compared with traditional hydraulic conductivity test results carried on in the same area. To test the applicability of this method, data coming from 59 wells located in the alluvial aquifer of Malagrotta waste disposal site, a large area of 160 ha near Rome, were analyzed and processed. Hydraulic conductivity values were estimated by applying the Dupuit's hypothesis for steady-state radial flow in an unconfined aquifer, as these are the hydraulic conditions in pumping wells for remediation purposes. This study aims to show that low-flow purging procedures in monitoring wells-carried out before sampling for groundwater characterization-represent an easy and inexpensive method for soil hydraulic conductivity estimation with good feasibility, if correctly carried on
Limpopo National Park (Mozambico): groundwater assessment as a tool for a sustainable management of the area
Full text linkThis paper deals with updated results coming from hydrogeological studies carried on the framework of the SECOSUD
Phase II, called “Conservation and equitable use of biological diversity in the SADC region (Southern African Development
Community), a project supported by the Italian Ministry of Foreign Afairs in the SADC, whose focus area includes South
Africa Development Countries. The main goal of the SECOSUD Phase II Project is the defnition and implementation of
scenarios for sustainable development, aimed at an equitable conservation of biodiversity resources and, as a consequence
of this target, the hydrogeological characterization, with the groundwater recharge assessment, of this area and its bufer
zone. Limpopo National Park is one of the jewels in the crown of Mozambique’s protected areas. As a matter of fact, sustaining the conservation of biodiversity, due to its complexity and multiple drivers, which stress it, is on frst a matter of water
environment assessment, as most ecosystems are highly dependent on the hydrological cycle and groundwater availability.
After gathering regional and local geological data, which let us set up a detailed geological map of the area under study,
pointing out the main outcropping geological units, with their main hydrogeological properties, the methodological approach
adopted has been to assess the potential infltration, applying the Inverse Hydrogeological Budget Technique, performed for
the focus area. Because of the lack of meteorological data referred to Limpopo National Park, it has been applied a spatial
distribution of precipitation measurements, collected in many gauge stations, located in the Kruger National Park during
the last 54 years, which represent an interesting rainfall historical series. The target of the study has been to assess a trend of
meteorological data with the aim of understanding how precipitations could afect groundwater recharge, and their infuence
on groundwater availability. The estimation of groundwater recharge is the tool for suggesting better water management in
the area, aimed to preserve as much biodiversity as people living in the bufer zone
Effects of climate change on groundwater feeding the Mazzoccolo and Capodacqua di Spigno Springs (Central Italy): First quantitative assestments
No full textIn Italy, the summer of 2017 was characterized by serious problems related to the water crisis that affected the entire national territory. The Municipality of Formia, as well as many other territories in the Latina Province, had to face heavy rationing of the water supply during the summer, with consequent inconvenience for the population. In this paper, two spring and their relative aquifers were studied: the Mazzoccolo Spring and the Capodacqua di Spigno Spring. For both aquifers, a hydrogeological water balance was calculated based on the collection of thermo-pluviometric data on an appropriate time series, at the meteorological stations present within and around the study area. The main goal was to establish, in the context of current climate change, the potential of the aquifers that feed these water resources. For the calculation of the active recharge, in order to have an estimation value of the supply volumes, data referred to four meteorological stations in the study area for a time series of 40 years (1959-1999) were collected and processed. The stations considered are the following: Gaeta, Itri, Esperia and SS Cosma e Damiano pluviometric stations. Each basin has been divided into finished square elements (FSE), with a size of 10000 m2, using a GIS software. The value of the effective infiltration to assign to each cell is a function of the annual rainfall value and the annual evapotranspiration value, both referred to the cell itself. The sum of all the values referred to each cell of the grid, provided the estimation of the aquifer annual average recharge as average annual volume. The same procedure was used for maximum, minimum and medium values of the rainfall on the time series considered and for the single annual rainfall value of 2017. Results confirmed the extraordinary nature of the drought event that occurred during the recharge period of 2017, showing a huge decrease of the average available water volume. In conclusion, for the Mazzoccolo and Capodacqua di Spigno Springs, future interventions are going to be planned for the catchment optimization in order to overcome any future possible water crises, even considering the permanent reserves, without compromising their medium and long term availability and their quality
Quali-quantitative considerations on low-flow well purging and sampling
Full text linkThis article deals with both the main advantages and issues related to groundwater purging and sampling that are usually carried out through the so-called low-flow methodology or with the method based on the purging of 3-5 well volumes, which is still widely used in environmental monitoring. A review of the recent literature concerning the technical characteristics, innovations and modelling related to low-flow sampling is presented. The aim is to provide to the reader a broad overview on this specific field application and offer a new vision, which considers two aspects: 1. The qualitative aspect, relating to the representativeness of the sample taken through a correct purging of the monitoring well and the consequent correct interpretation of hydrochemical data; 2. The quantitative aspect, related to the possibility of using water level data during purging and low-flow sampling operations to estimate the soil horizontal hydraulic conductivity, without further investigations. Low-flow sampling methodology can be very useful especially for alluvial aquifers, providing representative samples of groundwater and hydrodynamic characteristics of the aquifer, with reduced costs and times. These two aspects are both important in the context of an environmental monitoring plan for a potentially contaminated site
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