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Papers by Ivan Portoghese

Proceedings of the 39th IAHR World Congress

Proceedings, 2016

The Alimini water system, located in south eastern part of Italy, named Salento peninsula, is con... more The Alimini water system, located in south eastern part of Italy, named Salento peninsula, is constituted from two connected coastal lakes, Alimini Piccolo and Alimini Grande. Specifically, Alimini Piccolo is a small freshwater body, directly fed by rainfall and by shallow porous aquifer through of several springs. From '50s Alimini Piccolo provides the surrounding area with water for agriculture and domestic use. In June 2013, IRSA-CNR started a study concerning the quali-quantitative characterization of the hydrogeological system feeding the Alimini Piccolo, in order to investigate the potential for additional exploiting of the lake as a resource for drinking water. For the purpose, a monitoring system has been set up for an entire hydrological year. Continuous measurements of water level, electrical conductivity and temperature, such as quantitative and qualitative monitoring monthly campaigns both in groundwater and in the lake have been carried out. In order to support the above mentioned surveys, Electrical Resistivity Tomography (ERT) has been carried out to identify geological structures and hydrogeological features, to better understand the system feeding the Alimini Piccolo and to set the boundary conditions of the hydrological model useful to represent the water balance of the lake.

EGU General Assembly Conference Abstracts, Apr 1, 2016

Proceedings of the 39th IAHR World Congress

&lt;p&gt;The Mean Sea Level Aquifer (MSLA) of the island of Malta is a freshwater... more &lt;p&gt;The Mean Sea Level Aquifer (MSLA) of the island of Malta is a freshwater lens system sustained in a carbonate formation, floating on seawater in the bedrock. Given the specific hydrogeological and climatic conditions, the water table today reaches its maximum elevation at around 3 m amsl at the centre of the 316 Km&lt;sup&gt;2&lt;/sup&gt; island, with a maximum thickness of freshwater lens being about 90 m. Seawater intrusion occurs as an unavoidable effect of groundwater abstraction and the situation is further exacerbated during the dry summer period when water demands are higher.&lt;/p&gt;&lt;p&gt;Groundwater plays a major role in meeting the water demand of the Maltese islands and in this regard, is a strategic resource which needs to be preserved in terms of quality and quantity. It is therefore critically important to have an accurate understanding of the volume of fresh groundwater stored in the aquifer and how it is changing in response to changes in recharge, withdrawal and climatic regimes, to support an effective management which ensures the sustainability of this resource.&lt;/p&gt;&lt;p&gt;The status of fresh groundwater in the MSLA is assessed through vertical profiles of salinity along the water column of Deep Monitor Boreholes (DMBs) which penetrate partly or entirely through the brackish-water transition zone that separates freshwater from the underlying higher density seawater in freshwater lens systems. Salinity profiles were measured using a multiparametric probe (SEBA HYDROMETRIE KLL-Q-2 with MPS-D8 probe) lowered from the water table till the bottom of the DMBs measuring electrical conductivity (as a proxy for salinity), temperature, pressure and pH in three DMBs on a weekly basis over one year during the wet seasons.&lt;/p&gt;&lt;p&gt;The monitoring of salinity profiles over time in these DMBs allowed the detection of typical patterns of fresh/sea-water interface fluctuations according to the occurrence of external driving forces like precipitation and/or local abstraction.&amp;#160; The profiles were correlated with aquifer characteristics such as, fractures and orientation of strata in the DMBs which were determined through high resolution images captured with an optical televiewer probe (MOUNT SOPRIS QL40-OBI-2G).&lt;/p&gt;&lt;p&gt;The results show that the thickness of the transition zone varies in the DMBs according to the succession of dry and wet periods with maximum fluctuations of about 8 m. Furthermore, the interface depth results about 32 times the freshwater head inferring a deviation from the standard Ghyben-Herzberg coefficient of 40 for sharp interfaces. By analysing local geological conditions and time-series of total rainfall, groundwater abstraction, piezometric levels and salinity profiles, we identified occurrence mechanisms of three typical transition zones: (i) sharp interface, (ii) diffused interface, and (iii) step-like changes of salinity with depth. These types of interfaces, which are rather recurrent in space and time, lead us to gain a clearer understanding of the seawater intrusion dynamics triggered by variable abstraction conditions and drought periods.&lt;/p&gt;&lt;p&gt;The outcomes of this study illustrate the value of DMBs in establishing an effective monitoring framework for island groundwater bodies status, since the development of the transition zone is an important factor for managing freshwater abstraction from near-coastal and island aquifer systems.&lt;/p&gt;

Near Surface Geoscience 2015 - 21st European Meeting of Environmental and Engineering Geophysics, 2015

This study presents the results of a saline tracer test conducted on an unconfined alluvial aquif... more This study presents the results of a saline tracer test conducted on an unconfined alluvial aquifer placed in the Alento River Valley (Campania region, South-Western Italy) and monitored by Mise-a-la-Masse measurements. The aim of this test is the investigation of groundwater flow field by a time-lapse analysis. The work first introduces the local hydrogeology of the investigated system and the experimental set-up. The results of the geophysical tracer test are then described and followed by the discussion of several simulations conducted on a 3D electrical model of the system. Finally, the comparison between real and simulated datasets is discussed in order to highlight advantages and limitations of Mise-a-la Masse technique when applied for hydrogeological purposes.

Natural Hazards and Earth System Science, 2009

In the present work, the role played by vegetation parameters, necessary to the hydrological dist... more In the present work, the role played by vegetation parameters, necessary to the hydrological distributed modeling, is investigated focusing on the correct use of remote sensing products for the evaluation of hydrological losses in the soil water balance. The research was carried out over a medium-sized river basin in Southern Italy, where the vegetation status is characterised through a data-set of multitemporal NDVI images. The model adopted uses one layer of vegetation whose status is defined by the Leaf Area Index (LAI), which is often obtained from NDVI images. The inherent problem is that the vegetation heterogeneity-including soil disturbances-has a large influence on the spectral bands and so the relation between LAI and NDVI is not unambiguous. We present a rationale for the basin scale calibration of a non-linear NDVI-LAI regression, based on the comparison between NDVI values and literature LAI estimations of the vegetation cover in recognized landscape elements of the study catchment. Adopting a process-based model (DREAM) with a distributed parameterisation, the influence of different NDVI-LAI regression models on main features of water balance predictions is investigated. The results show a significant sensitivity of the hydrological losses and soil water regime to the alternative LAI estimations. These crucially affects the model performances especially in lowflows simulation and in the identification of the intermittent regime.

Natural Hazards and Earth System Science, 2011

The accuracy of rainfall predictions provided by climate models is crucial for the assessment of ... more The accuracy of rainfall predictions provided by climate models is crucial for the assessment of climate change impacts on hydrological processes. In fact, the presence of bias in downscaled precipitation may produce large bias in the assessment of soil moisture dynamics, river flows and groundwater recharge. In this study, a comparison between statistical properties of rainfall observations and model control simulations from a Regional Climate Model (RCM) was performed through a robust and meaningful representation of the precipitation process. The output of the adopted RCM was analysed and re-scaled exploiting the structure of a stochastic model of the point rainfall process. In particular, the stochastic model is able to adequately reproduce the rainfall intermittency at the synoptic scale, which is one of the crucial aspects for the Mediterranean environments. Possible alteration in the local rainfall regime was investigated by means of the historical daily time-series from a dense rain-gauge network, which were also used for the analysis of the RCM bias in terms of dry and wet periods and storm intensity. The result is a stochastic scheme for bias-correction at the RCM-cell scale, which produces a realistic representation of the daily rainfall intermittency and precipitation depths, though a residual bias in the storm intensity of longer storm events persists.

Hydrology and Earth System Sciences, 2008

Hydrology and Earth System Sciences, 2013

Various downscaling techniques have been developed to bridge the scale gap between global climate... more Various downscaling techniques have been developed to bridge the scale gap between global climate models (GCMs) and finer scales required to assess hydrological impacts of climate change. Such techniques may be grouped into two downscaling approaches: the deterministic dynamical downscaling (DD) and the statistical downscaling (SD). Although SD has been traditionally seen as an alternative to DD, recent works on statistical downscaling have aimed to combine the benefits of these two approaches. The overall objective of this study is to assess whether a DD processing performed before the SD permits to obtain more suitable climate scenarios for basin scale hydrological applications starting from GCM simulations. The case study presented here focuses on the Apulia region (South East of Italy, surface area about 20 000 km 2), characterised by a typical Mediterranean climate; the monthly cumulated precipitation and monthly mean of daily minimum and maximum temperature distribution were examined for the period 1953-2000. The fifth-generation ECHAM model from the Max-Planck-Institute for Meteorology was adopted as GCM. The DD was carried out with the Protheus system (ENEA), while the SD was performed through a monthly quantile-quantile correction. The SD resulted efficient in reducing the mean bias in the spatial distribution at both annual and seasonal scales, but it was not able to correct the miss-modelled nonstationary components of the GCM dynamics. The DD provided a partial correction by enhancing the spatial heterogeneity of trends and the long-term time evolution predicted by the GCM. The best results were obtained through the combination of both DD and SD approaches.

Advances in Geosciences, 2010

The accuracy of local downscaling of rainfall predictions provided by climate models is crucial f... more The accuracy of local downscaling of rainfall predictions provided by climate models is crucial for the assessment of climate change impacts on hydrological processes because the presence of bias in downscaled precipitation may produce large bias in the assessment of soil moisture dynamics, river flows, and groundwater recharge. In this study, the output of a regional climate model (RCM) is downscaled using a stochastic modelling of the point rainfall process able to adequately reproduce the daily rainfall intermittency which is one of the crucial aspects for the hydrological processes characterizing Mediterranean environments. The historical time-series from a dense raingauge network were used for the analysis of the RCM bias in terms of dry and wet daily period and then to investigate the predicted alteration in the local rainfall regime. A Poisson Rectangular Pulse (PRP) model (Rodriguez-Iturbe et al., 1987) was finally adopted for the stochastic generation of local daily rainfall as a continuous-time point process with forcing parameters resulting from the bias correction of the RCM scenario.

Sensors

At the local scale, environmental parameters often require monitoring by means of affordable meas... more At the local scale, environmental parameters often require monitoring by means of affordable measuring techniques and technologies given they need to be frequently surveyed. Streamflow in riverbeds or in channels is a hydrological variable that needs to be monitored in order to keep the runoff regimes under control and somehow forecast floods, allowing prevention of damage for people and infrastructure. Moreover, measuring such a variable is always extremely important for the knowledge of the environmental status of connected aquatic ecosystems. This paper presents a new approach to assessing hydrodynamic features related to a given channel by means of a beamforming technique that was applied to video sensing. Different features have been estimated, namely the flow velocity, the temperature, and the riverbed movements. The applied beamforming technique works on a modified sum and delay method, also using the Multiple Signal Classification algorithm (MUSIC), by acting as Synthetic Ap...

Science of The Total Environment

Aestimum, 2019

In this research an empirical evaluation of the economic impacts on tomato production due to the ... more In this research an empirical evaluation of the economic impacts on tomato production due to the reduced water availability for irrigation is proposed. A 16-years’ time series is considered (2001-2016) with regard to the Tavoliere delle Puglie agricultural district. Drought events occurred in the period of interest have caused economic impacts in terms of gross product and irrigation costs, with losses reaching 30% compared to years with regular water availability. These preliminary results calls for a wider drought management plan in which also economic instruments are included with the aim of minimizing economic impacts of irrigation water shortage.

Proceedings of the 39th IAHR World Congress

Proceedings, 2016

EGU General Assembly Conference Abstracts, Apr 1, 2016

Proceedings of the 39th IAHR World Congress

Near Surface Geoscience 2015 - 21st European Meeting of Environmental and Engineering Geophysics, 2015

Natural Hazards and Earth System Science, 2009

Natural Hazards and Earth System Science, 2011

Hydrology and Earth System Sciences, 2008

Hydrology and Earth System Sciences, 2013

Advances in Geosciences, 2010

Sensors

Science of The Total Environment

Aestimum, 2019