Ivan Portoghese

A GIS tool for hydrogeological water balance evaluation on a regional scale in semi-arid environments

A GIS tool to evaluate hydrogeological water balance based on a mass-balance model applied to surface and subsurface systems is discussed. The tool is designed for managers responsible for groundwater resource planning during conditions of water shortage. In developing the tool, the natural groundwater recharge was evaluated through the application of a soil water balance equation, and defined as the difference between the inflows (rainfall, irrigation) and the outflows (plant evapotranspiration, surface run-off). A distributed approach was used in the soil water balance equation to account for the spatial variability of climate and landscape features. Conversely the groundwater balance was calculated on a watershed or aquifer scale, using a lumped water balance equation, in which withdrawals for different uses were estimated together with inflows from other water bodies and coastal outflows. The model was implemented on a GIS platform with an automatic routine that manages all the data sets required and allows for the forecasting of groundwater storage volumes. Furthermore, the model was able to evaluate agricultural water demands under different climatic and management scenarios. A tool which provides a summary of the results and performs a statistical analysis for any portion of the study area was also implemented. The model was applied to a coastal region of Southern Italy. The averaged groundwater balance calculated by the model was in agreement with the piezometric head and chlorine concentration trends measured in selected monitoring wells.

A Bayesian vulnerability assessment tool for drinking water mains under extreme events

Drinking water security is a life safety issue as an adequate supply of safe water is essential for economic, social and sanitary reasons. Damage to any element of a water system, as well as corruption of resource quality, may have significant effects on the population it serves and on all other dependent resources and activities. As well as an analysis of the reliability of water distribution systems in ordinary conditions, it is also crucial to assess system vulnerability in the event of natural disasters and of malicious or accidental anthropogenic acts. The present work summarizes the initial results of research activities that are underway with the intention of developing a vulnerability assessment methodology for drinking water infrastructures subject to hazardous events. The main aim of the work was therefore to provide decision makers with an effective operational tool which could support them mainly to increase risk awareness and preparedness and, possibly, to ease emergency management. The proposed tool is based on Bayesian Belief Networks (BBN), a probabilistic methodology which has demonstrated outstanding potential to integrate a range of sources of knowledge, a great flexibility and the ability to handle in a mathematically sound way uncertainty due to data scarcity and/or limited knowledge of the system to be managed. The tool was implemented to analyze the vulnerability of two of the most important water supply systems in the Apulia region (southern Italy) which have been damaged in the past by natural hazards. As well as being useful for testing and improving the predictive capabilities of the methodology and for possibly modifying its structure and features, the case studies have also helped to underline its strengths and weaknesses. Particularly, the experiences carried out demonstrated how the use of BBN was consistent with the lack of data reliability, quality and accessibility which are typical of complex infrastructures, such as the water distribution networks. The potential applications and future developments of the proposed tool have been also discussed accordingly.

Impacts of Climate Change on Freshwater Bodies: Quantitative Aspects

In this chapter we present the results of the impact assessment on freshwater bodies in the Mediterranean region. Starting from the characterization of the general features of Mediterranean hydrology, main focus is given on large river basins discharging into the Mediterranean sea as well as to small and medium scale catchments representing almost half of the entire discharging basin. Groundwater representing a fundamental water resource for Mediterranean countries was also considered. Climate change impacts on the hydrological behavior of large river basins is investigated through the IRIS computational tool which was proved to be a versatile instrument for both climate studies and the assessment of model ability to simulate the hydrological cycle at catchment scale, taking advantage of the available observed discharge series to evaluate the reliability of future discharge projections. The results regarding some representative Mediterranean rivers using multiple climate models developed inside Circe have highlighted an open spread among twenty-first century projections. The problem of the effective information content of climate model simulations with respect to small scale impact studies is developed at the scale of medium and small catchments. Particularly at the space-time scales needed to describe the terrestrial water cycle in Mediterranean environments this is recognized among the most difficult problems facing both science and society. Therefore downscaling and bias-correction requirements have been treated in this chapter through specific methodologies which integrate dynamical downscaling with statistical downscaling always adopting ground based observation of climate variables as a powerful means to obtain more robust climate forcing for hydrological models. The assessment of climate change impacts on small and medium size catchments is developed through some representative case studies in which downscaling methodologies have been applied thanks to the availability of dense climate measurement networks. The impact assessment of water resources in the Apulia region (southern Italy) revealed a marked increase in the variability of hydrologic regimes as consequence of the increased rainfall variability predicted for the twenty-first century. Conversely only slight decreasing trends were detected in the annual water balance components. Similar results were found on a carbonate aquifer in Southern Italy in which a large Apennine spring have been selected as a significant hydrogeological systems with minimal anthropogenic pressures in the recharge areas. Finally a specific session is dedicated to the role of artificial dams in reducing the possible impacts of climate change. In particular, methodologies for the assessment of optimal dam dimensioning under climate change are presented as well as a reliability assessment based on water supply and demand imbalances.

Long-term climate sensitivity of an integrated water supply system: The role of irrigation.

The assessment of the impact of long-term climate variability on water supply systems depends not only on possible variations of the resources availability, but also on the variation of the demand. In this framework, a robust estimation of direct (climate induced) and indirect (anthropogenically induced) effects of climate change is mandatory to design mitigation measures, especially in those regions of the planet where the groundwater equilibrium is strongly perturbed by exploitations for irrigation purposes. The main goal of this contribution is to propose a comprehensive model that integrates distributed crop water requirements with surface and groundwater mass balance, able to consider management rules of the water supply system. The proposed overall model, implemented, calibrated and validated for the case study of the Fortore water supply system (Apulia region, South Italy), permits to simulate the conjunctive use of the water from a surface artificial reservoir and from groundwater. The relative contributions of groundwater recharges and withdrawals to the aquifer stress have been evaluated under different climate perturbations, with emphasis on irrigation practices. Results point out that irrigated agriculture primarily affects groundwater discharge, indicating that ecosystem services connected to river base flow are particularly exposed to climate variation in irrigated areas. Moreover, findings show that the recharge both to surface and to groundwater is mainly affected by drier climate conditions, while hotter conditions have a major impact on the water demand. The non-linearity arising from combined drier and hotter conditions may exacerbate the aquifer stress by exposing it to massive sea-water intrusion.

Modelling Crop Pattern Changes and Water Resources Exploitation: A Case Study

Agriculture and farming worldwide are responsible for numerous environmental threats, including degradation of land and water resources depletion. Underlining the dynamic interaction between bio-physical and socio-economic drivers is the key towards a more sustainable land and water management. With regard to a highly developed agricultural area in southern Italy, multi-regression models were developed to interpret the observed inter-annual variability of cropped land. Main drivers related to Common Agricultural Policy support, product market prices, crop yield and irrigation water availability were investigated. The adopted models revealed the different weighs of each driver. The findings reported the role that direct payments played in supporting the extension of irrigated crops, such as processing tomato. Likewise, the models pointed to decoupled payment scheme as the most important driver of change in the crop pattern over the last years.

Assessing the Impacts of Climate Change on Water Resources: Experiences From the Mediterranean Region

The most critical impacts of climatic change on the Mediterranean society and environment are likely to be associated with water availability. The whole area is expected to become vulnerable to the scarcity and irregular availability of water resources. In the framework of the FP6 EU CIRCE project (http://www.circeproject.eu/), a Regional Assessment of Climate Change in the Mediterranean (RACCM) was produced in 2013 to support the design of adaptation and mitigation policies on the whole region including Europe, North Africa, and the Middle-East. To this end, a set of coupled models has been developed to produce regional climate change projections. These projections allow assessment of the response of the Mediterranean Sea to climate change over the period 1950–2050 under the A1B hypothesis and to a large extent, the associated uncertainty. Some results concerning the use of CIRCE scenarios for the assessment of impacts on water resources are presented with an emphasis on the methodological approach to bridge the scale gaps between climate model structure and the resolution of basin-scale hydrology. Focusing on Southern Italy, the sustainability of surface and groundwater resources is explored. Additional results concerning a coastal catchment in Lebanon are presented. In this case study regarding a snow-dominated hydrological system, the combined effect of changes in temperature and precipitation is highlighted. The above methodological approach set-up for the Mediterranean area could be adopted for regions in Southeast Asia where in order to undertake similar impact studies, the local scale of investigation plays a determinant role for water resources assessment and flood protection.

Quantitative Interpretation of Time-lapse MALM Measurements During a Saline Tracer Injection in an Alluvial Aquifer

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.

Inducing Water Productivity from Snow Cover for Sustainable Water Management in Ibrahim River Basin, Lebanon

The aim of this paper is to explore the effects and linkages between snow cover areas, distribution, probability and measured water discharge along east Mediterranean coastal watershed using moderate-resolution satellite images (MODIS-Terra). The Nahr Ibrahim River is a typical Lebanese watershed with an area of 326 km2 stretching between the sea and mountainous terrain to the east. The largest snow cover often exists in January-February with snow-free conditions between June and November. Image analysis enabled to analyze the temporal variability of the mean and maximum monthly areas of snow cover between 2000 and 2013. Snow cover dynamics were compared with the discharge from main springs (Afqa and Rouaiss) feeding the river and the probability of snow cover was estimated. The mean monthly snow cover, snow melting rates and springs discharge were found to be in direct relationship. In addition, the measured water discharge at the river mouth was found to be higher than the discharge of the two main feeding springs. This indicates a contribution of groundwater to the stream flow, which is again in direct connection with snow melting at the upper bordering slopes and probably from neighboring watersheds. Considering the characteristics of the mountainous rocks (i.e. Sinkholes, fissured and karstified limestone), the pedo-climatic and land cover conditions affect the hydrological regime which is directly responding to the area and temporal distribution of snow cover, which appears after two months from snowing events. This is reflected on water productivity and related disciplines (Agricultural yield, floods). This study highlights the potential of satellite snow detection over the watershed to estimate snow cover duration curve, forecast the stream flow regime and volume for better water management and flood risk preparedness.

Actual evapotranspiration by use of MODIS data

The aim of this research is to assess a technique to retrieve actual evapotranspiration (ET) maps from remote sensing images by the combination of two different procedures. The first one, known as triangle method, computes the evapotranspiration fraction (EF) defined as the ratio LE/Rn, where Rn is the net radiation at the surface and LE is the latent heat flux. LE is directly proportional to ET. In order to retrieve LE, and consequently the surface evapotranspiration, a second procedure computes the net radiation of the investigated area. Therefore, by inversion, it is possible to obtain an estimate of the ET. The validation of these variables, net radiation and evapotranspiration derived from MODIS data, has been undertaken on the Capitanata area, Southern Italy, by comparison of model results with in-situ measurements provided by the Consorzio per la Bonifica della Capitanata di Foggia.

Climate Change Impacts on Water Resources Management with Particular Emphasis on Southern Italy

A methodology to use climate change information in water resources evaluation is developed through a meaningful case study in southern Italy (the Apulia region). The problem of the effective information of climate model simulations with respect to small scale impact studies is developed taking into account the limited predictive capability of climate models. Therefore downscaling and bias-correction requirements are treated through a specific methodology based on a quantile variable correction adopting ground based observation of climate variables. The meteorological forcing for the impact study are obtained through the downscaling of atmospheric variables produced by a Regional Climate Model (RCM) called Protheus. The impact assessment on the water balance of the Apulia region (southern Italy) revealed a marked increase in the variability of hydrologic regimes (both runoff and groundwater recharge) as consequence of the increased rainfall variability predicted for the twenty-first century, while preserving a decreasing in the annual trend. Moreover, the analysis of climate change effects was performed focusing on the rainfall-discharge process of a strategic karst spring supplying the Apulia aqueduct. In this case study, no substantial variations in the annual mean discharge are recognized, although a marked decrease in the mean monthly discharge was found between October and December, which represent the start of the recharge period of Apennine aquifers. Such results represent a crucial water management issue that has to be addressed in terms of adaptation to meet future water resources requirements.