Abstract:In this research, univariate and bivariate statistical methods were applied to rainfall, river and piezometric level datasets belonging to 24-year time series . These methods, which often are used to understand the effects of precipitation on rivers and karstic springs discharge, have been used to assess piezometric level response to rainfall and river level fluctuations in a porous aquifer. A rain gauge, a river level gauge and three wells, located in Central Italy along the lower Pescara River valley in correspondence of its important alluvial aquifer, provided the data. Statistical analysis has been used within a known hydrogeological framework, which has been refined by mean of a photo-interpretation and a GPS survey. Water-groundwater relationships were identified following the autocorrelation and cross-correlation analyses. Spectral analysis and mono-fractal features of time series were assessed to provide information on multi-year variability, data distributions, their fractal dimension and the distribution return time within the historical time series. The statistical-mathematical results were interpreted through fieldwork that identified distinct groundwater flowpaths within the aquifer and enabled the implementation of a conceptual model, improving the knowledge on water resources management tools.
Iron and manganese are two of the most common contaminants that exceed the threshold imposed by international and national legislation. When these contamination occurs in groundwater, the use of the water resource is forbidden for any purposes. Several studies investigated these two metals in groundwater, but research focused in the Central Adriatic area are still lacking. Thus, the objective of this study is to identify the origin of Fe and Mn contamination in groundwater and the hydrogeochemical processes that can enrich aquifers with these metals. This work is based on hydrogeochemical and multivariate statistical analysis of analytical results undertaken on soils and groundwater. Fe and Mn contamination are widespread in the alluvial aquifers, and their distribution is regulated by local conditions (i.e. long residence time, presence of peat or organic-rich fine sediments or anthropic pollution) that control redox processes in the aquifers and favour the mobilisation of these two metals in groundwater. The concentration of iron and manganese identified within soil indicates that the latter are a concrete source of the two metals. Anthropic impact on Fe and Mn contamination of groundwater is not related to agricultural activities, but on the contrary, the contribution of hydrocarbons (e.g. spills) is evident.
The water-rock interaction is discussed in this study for some Central Apennine aquifers and their relative springs, where the geological and hydrogeological setting is potentially responsible for hydrocarbon contamination. The contamination is related to the presence of limestone formations with high organic content that are connected to the genesis of hydrocarbons in the Central-Southern Apennines. Thanks to a multidisciplinary approach based on a seasonal monitoring of hydrogeological, hydrogeochemical, organic chemical, and isotopic variables, and to a detailed geological analysis, it was possible to demonstrate that the bituminous schists within the bituminous dolomite formation (a Triassic Formation presents in the Gran Sasso acquifer), the bituminous intercalations within the Bolognano Formation (an Olocenic calcareous Formation in the Majella acquifer), and the petroleum-saturated rocks of the Bolognano Formation (in the Morrone acquifer) are all able to leach hydrocarbons into groundwater. The results suggest that more detailed studies are required for areas where lithologies with fossil organic components are present. Insights should further investigate the interaction between groundwater and rocks in terms of organic compounds as well as inorganic compounds. In particular, the study also suggests that the supplementary quantification of hydrocarbon compounds in bituminous rock and the leaching tests are analyses that provide reliable results. From the normative point of view, the results of the study can be useful when dealing with hydrocarbon contamination resulting from anthropogenic activities within catchments where formations with high concentration of organic matter are present. In these cases, it will possible to assess the natural background concentrations and review the threshold values upwards.
Abstract:In this research, univariate and bivariate statistical methods were applied to rainfall, river 14 and piezometric level datasets belonging to 24 years long time series
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