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The objective of this paper is to present a methodology for the quantification of drought risk in agriculture in Mediterranean regions. The methodology consists of three interrelated components: the estimation of the severity and frequency of droughts, the simulation of water use and crop yield production and the assessment of annualized risk in agriculture. Both rainfed and irrigated agriculture are considered through the concept of vulnerability. The methodology is demonstrated by a case study in Eastern Crete [ABSTRACT FROM AUTHOR]

Recent history has demonstrated that extreme hydrological events such as floods and droughts can create additional stress on water supplies essential for human and ecosystem health. As stated several times by European Environmental Agency, the prudent and efficient use of water is thus an important issue in Europe and a number of policies and mechanisms have been used or have been formulated to ensure sustainable use of water in the long term. Urban uses are responsible of almost the 17% of the total European fresh water consumption and they are rapidly growing depending on the extension of urban areas and concentration of population in cities. The present chapter will discuss the phases in the development of a drought management plan starting from the estimation of water supplies and demands, the evaluation of drought risk and urban area vulnerability and, finally, planning procedures and possible mitigation measures [ABSTRACT FROM AUTHOR]

This chapter revises the measures and practices that can be applied by the agriculture sector, rainfed and irrigated agriculture, to reduce both water demand and water consumption to mitigate the impacts of droughts. The analysis focuses on water conservation and water saving practices and management measures, which may lead to reduce the demand, control supplies and to improve the efficient use of water and water productivity [ABSTRACT FROM AUTHOR]

The severe drought events recently occurred all over the world have increased awareness of the harmful impacts they cause. Since drought, unlike other natural disasters, evolves in a long period of time, an effective reduction of related impacts is possible by implementing appropriate mitigation measures planned in advance, according to the indications provided by monitoring systems. In this chapter, the importance of a legislation for a correct drought management, based on a proactive approach, namely including both long-term actions oriented to reduce vulnerability of water supply systems and short-term actions to be implemented during droughts, is discussed. Moreover, the use of multicriteria analysis to compare different mitigation measures and to find the preferable combination of long and short-term actions is recommended. Finally, a framework for a timely implementation of drought mitigation measures and the adoption of an effective monitoring system for the evaluation of drought risk is presented [ABSTRACT FROM AUTHOR]

In this chapter the study of a coastal aquifer located in South-Western Sicily (between the towns of Marsala and Mazara del Vallo) is presented, carried out using geochemical, hydro-geological and geophysical techniques. The aquifer has been over-exploited to the point of being subject to intense and worrisome salt-water intrusion.A preliminary chemical and physical characterization of the waters was carried out; this included measuring their conductivity and their chloride content. This allowed to detect the marine intrusion wedge in the coastal aquifer. A series of electromagnetic soundings, suitably calibrated by well logs, were effected in the whole area and allowed to create a 3D interpretative model of the resistivity distribution in the aquifer, thereby enabling to recognize the main intrusion directions and the pattern of the aquifer bed. Furthermore an integrated geophysical 2D section was carried out along a line roughly perpendicular to the coast, in one of the zones that is particularly involved in the intrusion phenomenon. Field measures included ERT, IP, TDEM and seismic soundings, all of which were aimed at reconstructing a highly detailed geophysical section. The seismic soundings clearly show the lateral variation between the fresh and salt water, such as the overburden and the clayey bed of the aquifer. The final target of this research is to propose an optimized management-model of underground resources. The lessons drawn from the use of different techniques for defining geophysical profiles suggest an integrated methodology to identify in detail the sea intrusion zone in aquifers. Therefore, the methodology used can be suitably extended and exported for studing and monitoring many similar Mediterranean coastal areas [ABSTRACT FROM AUTHOR]

Groundwater monitoring requires the realization of a network of observation points selected on the basis of hydrogeological and hydrodynamic characteristics of aquifers, by means of which it is possible to carry out a real time control of groundwater resources using indicators of the state and consequent forecasting instruments of drought phenomena. Such criteria has been utilized in the case of a hydrostructure chosen after a preliminary hydrogeological analysis of main aquifer systems of the eastern part of Sicily. The chosen hydrostructure belongs to the hydrogeological system of Mt. Etna and constitutes the north-eastern flank of the volcano in which a considerable amount of water resources are stored that feed important springs and aqueduct networks of large municipalities. ∈dent The hydrodynamic behaviour of the aquifer, analysed on the basis of piezometric data and discharge of the springs, has highlighted a different temporal response with respect to the input of rainfall. Based on the average storage capacity, the renewal rate of the dynamic resources indicates a poor regulating ability of the aquifer over the long term. Taking into account current exploitation of aquifer, a correct management of the available resources needs a careful and continuous observation of the conditions of the aquifer in relation to variations in pluviometric inputs [ABSTRACT FROM AUTHOR]

In the southern regions of Mediterranean Europe, the greatest part of water resources for supply systems are derived from artificial reservoirs. A simplified approach to the need of inserting water quality aspects in the mathematical optimization model can be achieved considering the trophic state of reservoirs. In recen91t years, Trophic State Index (TSI) based on Carlson's (1977) classification appears to have obtained general acceptance as a reasonable manner of classifying stored water in reservoirs; it enables to insert quality constraint in the water management optimization model also considering large size multi-reservoir and multi-user systems. Using TSI index and concentration density values of the most toxic algae, water quality aspects can be easily considered in an optimization model specifically designed for large system management optimization. The usefulness of a mixed quantity-quality optimization approach has been confirmed by WARGI application to a real multi-reservoir water resources system in southern Sardinia [ABSTRACT FROM AUTHOR]

Definition of a synthetic index for classifying the quality of water bodies is a key aspect in integrated planning and management of water resources systems. In previous works (Salis et al., 2005; Sechi and Sulis, 2005), based on EU and Italian guidelines for water quality in surface reservoirs, a water system optimization modelling that considered a quality index based on the adoption of a small number of parameters has been proposed. This chapter analyses the feasibility of an index that considers quality parameters estimated both on the basis of the overall trophic state of the water body as on concentration density values of the most toxic species of algae. This index enables to describe the conditions limiting water use due to excessive nutrient enrichment in the water body and to the health hazard linked to toxic algae blooms. Application to the Flumendosa-Campidano water system highlighted the usefulness of this approach for obtaining a synthetic quality index in complex water resource systems [ABSTRACT FROM AUTHOR]

The chapter illustrates a Decision Support System (DSS) for multi-reservoir water resource systems, named WARGI (Water Resources system optimization aided by Graphical Interface). WARGI was upgraded in the SEDEMED II Project to implement a mixed approach that uses optimization and simulation techniques which identifies short and medium-term actions to be implemented in system management according to a proactive approach. Under drought conditions, the DSS aims to predict in advance the consequences of management assumptions in a predefined system configuration. The optimization module considers future hydrological and demand scenarios to modify the set of decision variables to be adopted by the simulation module. Lastly, WARGI's application to the water resource system of Southern Sardinia (Italy) is illustrated [ABSTRACT FROM AUTHOR]

Droughts in arid and semiarid Mediterranean river basins have an increasing socioeconomic and environmental impact. The problem is especially complex in basins where droughts are very frequent and intense and where water resources are under a massive use. For that reason in the Mediterranean basins it is necessary to manage the water resources in constant alert in order to relieve the consequences of a drought. In this chapter a complete methodology for the mitigation of the droughts is defined. The methodology includes different tools: from the definition of an alert system for the different types of drought up to the simulation and optimization software for water system management. This methodology has been applied to the different hydrographic basins included in the Confederaciòn Hidrogràfica del Jùcar (CHJ, the local water agency) and it has been currently used during the extreme drought occurred in the Jùcar river basin since the hydrological years 2004/05. This chapter shows how the proposed methodology is able to forecast the occurrence of a drought and to realize a water resources management focused on the mitigation of the economic, social and environmental effects of water shortage [ABSTRACT FROM AUTHOR]

Two basic characteristics of meteorological drought were analysed in this study. Namely the severity and the areal extent of drought. Severity was represented by two general drought indices the Standardised Precipitation Index and the Reconnaissance Drought Index. A spatial distribution model, based on the reciprocal of the square distance, was employed to model the spatial extent of drought. Annual drought maps based on discretized platforms were produced for the selected case study in Eastern Crete. Eastern Crete is a drought prone area of Greece consisting of the prefectures of Heraklio and Lassithi. It was shown that an effective way to estimate the areal extent of each level of drought is to use the cumulative "or more" curves, in which the level of drought is plotted versus the area affected by this or by a higher level of drought [ABSTRACT FROM AUTHOR]

The Palmer drought severity index (PDSI) has been developed for the Great Plains of USA, considering the environmental conditions and the crops in the area. After testing the applicability of the PDSI for Southern Portugal, a modification of the water balance was attempted assuming dryland olives as the drought-reference crop and using the FAO methodology to compute the crop evapotranspiration. All basic procedures of the Palmer method were kept, mainly those relative to the anomaly index and the PDSI. Results show that the modified PDSI behaves coherently with the original PDSI but its behaviour responds better to the observed drought conditions, characterized with the SPI. Particularly, its response to different soil water holding capacities is more coherent than the one of the original PDSI [ABSTRACT FROM AUTHOR]

Evapotranspiration (ET) is one of the main water balance components, and its actual value appears to be the most difficult to measure directly. Therefore, the choice of reliable models capable of predicting spatially distributed actual ET represents a drought monitoring fundamental aspect. This chapter presents a brief introduction to the main remote sensing methods for ET estimate and, by means of ground ET measurements carried out through eddy covariance systems at three different sites in southern Italy, analyzes the performance given by the Surface Energy Balance Algorithm for Land (SEBAL) model using images of the Moderate Resolution Imaging Spectroradiometer (MODIS) on areas characterized by different physiographic and vegetative conditions (sparse vegetation, crop canopy and high mountain vegetation). The distributed results obtained for different days from summer 2004 to summer 2006 on a wide southern Italian area pointed out generally good ET predictions in the eddy covariance sites, also if some differences arose depending on the type and density of vegetation [ABSTRACT FROM AUTHOR]

Drought management at a regional level necessitates the use of suitable instruments for monitoring, analysis and decisions support. A new index of agricultural drought, DTx, based on the daily transpiration deficit calculated by a water balance model has been defined and tested in three Mediterranean areas giving good results. A new module for DTx calculation has been implemented in the CRITeRIA water balance model as well as new algorithms to simulate cereals yield with the WOFOST methodology. A comparison between DTx values and the local climatology has been introduced in order to quantify the anomaly revealed by the index statistically. Therefore DTx can be associate with pluviometric and hydrological indices to better describe drought effects in different fields. Information on drought are collected in a single database and diffused by a dedicated website to support the regional management program defined with local authorities and water supply consortia. The program goals are to define the reference areas, identify an adequate system of monitors and alerts to help decisions, indicate proactive measures and spread knowledge and awareness on drought [ABSTRACT FROM AUTHOR]

Unlike other natural disasters, drought events evolve slowly in time and their impacts generally span a long period of time. Such features do make possible a more effective mitigation of the most adverse effects, provided a timely monitoring of an incoming drought is available Among the several proposed drought monitoring indices, the Standardized Precipitation Index (SPI) has found widespread application for describing and comparing droughts among different time periods and regions with different climatic conditions. However, limited efforts have been made to analyze the role of the SPI for drought forecasting The aim of the chapter is to provide two methodologies for the seasonal forecasting of SPI. In the first methodology, the transition probabilities from a current drought condition to another in the future, and from a single value of current SPI to a drought class are derived as functions of the statistics of the underlying monthly precipitation process. The proposed analytical approach appears particularly valuable from a practical stand point in light of the difficulties of applying a frequency approach or a Markov chain approach, due to the limited number of transitions generally observed even on relatively long SPI records. In the second methodology, SPI forecasts at a generic time horizon M are analytically determined, in terms of conditional expectation, as a function of a finite number of past values of monthly precipitation. Forecasting accuracy is estimated through an expression of the Mean Square Error, which enables to derive confidence intervals of prediction. Validation of the derived expressions is carried out by comparing theoretical forecasts and observed SPI values. The methodologies have been applied to the series of SPI, based on monthly precipitation observed in Sicily over 40 rain gauges in the period 1921-2003. Results seem to confirm the reliability of the proposed methodologies, which therefore can find useful application within a drought monitoring system [ABSTRACT FROM AUTHOR]

SPI time series in a 12 month time scale from 6 sites in Alentejo and Algarve, in the south of Portugal, within the period from October 1896 to September 2005, were divided into three or four periods depending on the data set length and a Loglinear modeling approach has been used to investigate differences relative to drought class transitions among these periods. Four drought severity classes were considered. The drought class transitions were computed for the different periods to form a 3-dimensional contingency table. The application of Loglinear modeling to these data allowed the comparison of the periods in terms of probabilities of transition between drought classes in order to detect a possible trend in time evolution of droughts which could be related to climate change [ABSTRACT FROM AUTHOR]

The Regional Hydrological Bulletin is an operational instrument studied to supply quantitative hints of the Piedmont Region main hydrological river basins state with simple and exhaustive communication modalities. The aim is to evidence the potential established of drought conditions and the insufficient availability of water resource on a regional territory. In order to realize this tool finalized to support the water resource management, contents, methodologies and an appropriate language have been developed, in a framework of climatologic reference. Moreover, the Bulletin supplies, through the statistic analysis of the SPI (Standardized Precipitation Index), an assessment of the short-term drought conditions over river basin spatial scale. This monitor includes all the resources flowed to the environment system in terms of rain volumes, water reservoirs stored in the not-perennial snowy mantle and the streaming capacities of the main watercourses [ABSTRACT FROM AUTHOR]

This chapter presents an overview of the occurrences and effects of droughts through a study of the Standard Precipitation Index (SPI) in the Emilia-Romagna region, which is located in the northern-central part of the Italian peninsula. The link between this index and large-scale atmospheric circulation was investigated and the SPI index was also used to predict drought. The study describes the development of a method of forecasting SPI index based on an earlier Interregional project (SEDEMED), involving a statistical downscaling scheme model using as input the large-scale seasonal forecasts obtained from Atmospheric Global Circulation Models. The downscaling scheme, which has already been used with relatively good results to predict surface parameters of temperature and precipitation, is applied to the SPI index, providing a statistical regionalization of this indicator [ABSTRACT FROM AUTHOR]

In dealing with drought, a proactive approach requires a drought monitoring, a drought forecasting and an estimation of extreme dry event return times. For this purpose a useful tool is the drought bulletin where all the available information and analyses are collected and updated. In this chapter the main aspects of such approach are described and some sample applications for the Mediterranean area are shown. Results suggest that for a drought risk assessment there is not a unique analysis procedure; however, an ensemble of different kinds of analyses can provide useful information in preventing and minimizing the negative effects of drought events [ABSTRACT FROM AUTHOR]