Marco Giacopetti

Analysis of mountain springs discharge time series in the Tennacola stream catchment (central Apennine, Italy)

The mountain portion of the Tennacola stream basin, which is located in the northeast sector of the Sibillini Mountains (Central Apennines, Italy), has a large number of springs exploited for drinking water. The presence of lithotypes with different hydraulic conductivity allowed the formation of two main groups of springs with different discharge and regime. This paper aims to provide new insights about the groundwater circulation within carbonate and karst complexes. In detail a study based on spring hydrograph analysis using the MRC method and on the main statistical parameters has been carried out, in order to evaluate the main features related to the flow paths and the main hydrogeological properties of the aquifers studied. The results allowed to characterize the main hydrogeological features of the aquifers and to evaluate the dimension of the recharge areas.

Groundwater recharge estimation using spring hydrographs: the case of the Tennacola carbonate aquifer (central Apennine, Italy)

The recharge of an aquifer is fundamental to evaluate the availability of the resource and for planning its use over the time.In general, indirect methods are widely used, because these are based on the rainfall, evapotranspiration and runoff data. These three parameters are not always simple to evaluate in relation to the possible presence of errors in the available data, malfunction of instruments or difficulty to make a monitoring in relation to the complexity of the area, with consequent uncertainty on the results. In such situations, the use of a direct method could be useful to estimate more accurately the aquifer recharge.A common direct method is based on the analysis of the spring hydrographs, i.e. the discharge monitored at the spring. In this work, a spring hydrograph from the central Apennines of Italy has been analysed in order to estimate the average recharge value feeding the aquifer.

Method and Excel VBA Algorithm for Modeling Master Recession Curve Using Trigonometry Approach

A new method was developed and implemented into an Excel Visual Basic for Applications (VBAs) algorithm utilizing trigonometry laws in an innovative way to overlap recession segments of time series and create master recession curves (MRCs). Based on a trigonometry approach, the algorithm horizontally translates succeeding recession segments of time series, placing their vertex, that is, the highest recorded value of each recession segment, directly onto the appropriate connection line defined by measurement points of a preceding recession segment. The new method and algorithm continues the development of methods and algorithms for the generation of MRC, where the first published method was based on a multiple linear/nonlinear regression model approach (Posavec et al. 2006). The newly developed trigonometry-based method was tested on real case study examples and compared with the previously published multiple linear/nonlinear regression model-based method. The results show that in some cases, that is, for some time series, the trigonometry-based method creates narrower overlaps of the recession segments, resulting in higher coefficients of determination R2 , while in other cases the multiple linear/nonlinear regression model-based method remains superior. The Excel VBA algorithm for modeling MRC using the trigonometry approach is implemented into a spreadsheet tool (MRCTools v3.0 written by and available from Kristijan Posavec, Zagreb, Croatia) containing the previously published VBA algorithms for MRC generation and separation. All algorithms within the MRCTools v3.0 are open access and available free of charge, supporting the idea of running science on available, open, and free of charge software.

Pliocene-Pleistocene geomorphological evolution of the Adriatic side of central Italy

Abstract This work is a significant contribution to knowledge of the Quaternary and pre-Quaternary morphogenesis of a wide sector of central Italy, from the Apennine chain to the Adriatic Sea. The goal is achieved through a careful analysis and interpretation of stratigraphic and tectonic data relating to marine and continental sediments and, mostly, through the study of relict limbs of ancient landscapes (erosional surfaces shaped by prevailing planation processes). The most important scientific datum is the definition of the time span in which the modelling of the oldest morphological element (the “summit relict surface”) occurred: it started during Messinian in the westernmost portion and after a significant phase during middle-late Pliocene, ended in the early Pleistocene. During the middle and late Pleistocene, the rapid tectonic uplift of the area and the climate fluctuations favoured the deepening of the hydrographic network and the genesis of three orders of fluvial terraces, thus completing the fundamental features of the landscape. The subsequent Holocene evolution reshaped the minor elements, but not the basic ones.

Application of the MRC method to the study of some mountain springs in the Tennacola stream catchment (central Apennine, Italy)

The study concerns part of the plain sector of Aosta Valley (NW Italy). The investigated area is located between the cities of Sarre-Gressan and Pollein-Saint Christophe and is characterized by the presence of hexavalent chromium in the main shallow unconfined aquifer. The pollution is probably related to the negative environmental effects induced by the industrial steel production that since 1915 is present over the area. Since 1990 the industrial area was subjected to a number of direct investigations aimed to assess the contamination intensity. A preliminary remediation activity has been developed in last decades but the contaminants have been still observed in the groundwater monitoring network. This study highlights the set-up of a groundwater conceptual and numerical model of the shallow aquifer aimed to better understand and analyze the transport dynamics of hexavalent chromium in the local aquifer. The simulation is performed using the specific finite element software Feflow for groundwater flow and mass transport modeling. The hydrogeological setting of this area is related to the different sedimentary glacial, lacustrine and fluvial processes which characterized the bottom of the Aosta valley during the Quaternary. The shallow 80m-width aquifer is constituted by sandy to gravelly deposits and presents rare silty lens while its bottom is characterized by a decametric lacustrine silty level. The main aims of the numerical model are to give a more unequivocal explanation of the origin of the contamination and to support the predictive analyses in order to design an efficient site remediation for soil and groundwater. This represents a fundamental task in order to preserve the safety of the public water uses supplied by the aquifer. The preliminary hypothesis about the source of contaminations are still uncertain and referred to different scenarios that have to be further investigated by comparing monitoring data and transient flow simulation conditions.

Deep Seated Gravitational Slope Deformations and Large Landslides Interfering with Fluvial Dynamics; Examples from Central Apennines (Italy)

The study, developed over a wide mountain sector of the central Apennines (Italy), highlights the role of Deep Seated Gravitational Slope Deformations (DSGSD) in the evolution of a mountain portion of the Chienti river valley. Radiocarbon dating and geomorphological considerations, testify that a lateral spreading, developed on a large scale, has triggered large landslides in correspondence of the thalweg. These phenomena have repeatedly dammed the river bed (certainly since the end of the late Pleistocene) creating temporary lakes which lasted also for a long time. The high seismicity and the persistence of conditions favorable to the development of gravitational phenomena, in an area currently occupied by an important communication route, attest to the high degree of risk present in this sector of the Apennine.

Geomorphological evolution of the middle-lower reach of the Tronto river (central Italy), during the last 200 years: impacts on flood hazard

The geomorphological dynamics is an important indicator for understanding processes of river erosion and sediment transport useful to plan appropriate remedial works along the rivers, so as not to modify the fragile equilibrium of the river itself. The present study aims at improve the knowledge on the geomorphological evolution of the Tronto river between the rivers mouth and the town of Ascoli Piceno through the analysis of historical maps and aerial photos covering different time spans.The retrieval of historical maps has allowed the reconstruction of the geomorphological evolution of the river bed and of the intervention aimed at river banks protection or, sometimes, for agricultural and industrial use.The interventions along the river beds began around the early 1900s (following the disastrous events of 1897 and 1898), resulting in a strong reduction of the floodplain width, from about 330 up to 210 meters and a rectification of the same with the construction of embankments up to 6 meters above the thalweg; these interventions were more intense at the mouth. The mismanagement of the terminal reach, among other things, after the interventions started in 1978 with the overall reduction in the flow section of the river, will favor the expansion of the flow during the 1992 flood event. The analysis, carried out in a GIS environment, evidenced as the interventions made along the river, have progressively modified almost all of the river reach for a length of over 20 km, reducing the typical cross section of about 50%.