Brunella Bonaccorso

Spatial Variability of Drought: An Analysis of the SPI in Sicily

An analysis of drought in Sicily from 1926 to 1996 is presented.In identifying drought over the region, both the NCEP/NCARreanalysis precipitation data and those observed in 43 gauges,located quite uniformly over the territory of the Island, areused. Drought occurrence is estimated by means of theStandardized Precipitation Index (SPI). To study long-termdrought variability, a Principal Component Analysis was appliedto the SPI field.Results suggest that the entire Island is characterised by adrought variability with a multi-year fluctuations and atendency towards drier periods from the seventies onward. Apreliminary comparison between results obtained using themeteorological large-scale analysis and that derived from actualobservations on the ground shows a general good agreement,although further efforts are needed to get a better downscalingof the large-scale precipitation fields. Furthermore, byapplying orthogonal rotations to the principal componentpatterns, it has been found that three distinct areas havingcoherent climatic variability may be identified.Finally, the sensitivity of the SPI values on the calibrationperiod is also investigated.

Methods and tools for drought analysis and management

Table of contents List of contributors Preface Part I: Drought monitoring and forecasting Drought monitoring and forecasting at large scale I. Bordi and A. Sutera Monitoring and forecasting drought on a regional scale: Emilia-Romagna region C. Cacciamani, A. Morgillo, S. Marchesi and V. Pavan Development of the Piedmont Region Hydrological Bulletin as a support to water resources monitoring and management C. Ronchi, A. Vargiu, R. Pelosini, A. Salandin, D. Rabuffetti and S. Barbero Is drought occurrence and severity increasing due to climatic change? Analysing drought class transitions with loglinear models E. E. Moreira, A.A. Paulo and L.S. Pereira Stochastic forecasting of drought indices A. Cancelliere, G. Di Mauro, B. Bonaccorso and G. Rossi Part II: Drought description through agrometeorological indices Use of a new agricultural drought index within a regional drought observatory A. Matera, G. Fontana,V. Marletto, F. Zinoni, L. Botarelli and F. Tomei Distributed estimation of actual evapotranspiration through remote sensing techniques G. Calcagno, G. Mendicino, G. Monacelli, A. Senatore and P. Versace Testing a modification of the Palmer Drought severity Index for Mediterranean environments L.S. Pereira, R. Rosa and A.A. Paulo Regional drought identification and assessment. Case study in Crete G. Tsakiris, D. Tigkas, H. Vangelis and D. Pangalou Part III: Water resources management under drought conditions Drought management decision support system by means of risk analysis models J. Andreu, M.A. Perez , F.J. Ferrer, A. Villalabos and J. Paredes Mixed simulation- optimization technique for complex water resources systems analysis under drought conditions G. M. Sechi and A.Sulis Reservoirs water-quality characterization for optimization modelling under drought conditions: Part I - Reservoirs trophic state characterization B. Begliutti, P. Buscarinu, G. Marras, G.M. Sechi and A. Sulis Reservoirs water-quality characterization for optimization modelling under drought conditions: PART II - Water-quality optimization modelling G. M. Sechi and A. Sulis Part IV: Monitoring and management of groundwater under drought conditions Methods and tools for groundwater monitoring aimed at the water resources management under drought conditions V. Ferrara Study and monitoring of salt water intrusion in the coastal area between Mazara del Vallo and Marsala (South-Western Sicily) P. Cosentino, P. Capizzi, G. Fiandaca, R. Martorana, P. Messina and S. Pellerito Part V: Drought impacts and mitigation measures Guidelines for planning and implementing drought mitigation measures G. Rossi, L. Castiglione and B. Bonaccorso Drought impacts in agriculture: water conservation and water saving practices and management L.S. Pereira Assessment of water shortage in urban areas C. Bragalli, G. Freni and G. La Loggia Drought risk in agriculture in Mediterranean regions. Case study: Eastern Crete G. Tsakiris and D. Tigkas Subject index

Guidelines for Planning and Implementing Drought Mitigation Measures

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

Stochastic Forecasting of Drought Indices

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

Characterizing Drought Risk in a Sicilian River Basin

The chapter summarizes the results of the application of proposed methodologies for drought characterization and risk assessment in water supply systems to the Italian case study, namely the Simeto River basin in Sicily. In particular, after a general description of the case study, the results of the drought identification, carried out by means of several drought indices and methods such as the Standardized Precipitation Index (SPI), the Palmer Hydrological Drought Index (PHDI) and the Run Method, are presented. The application of a methodology developed for the assessment of return periods of drought events identified on historical series of annual precipitation is also reported. Then, the methodology for risk assessment presented in chapter 6 is applied to the Salso-Simeto water supply system, which is a part of the larger system of the Simeto River. In particular, a Montecarlo simulation of the system is carried out in order to assess both unconditional (long term) and conditional (short term) drought risk. Also, drought impact assessment on rainfed agriculture is presented. Finally, drought mitigation measures historically adopted within the Simeto River basin in order to reduce drought impacts in urban and agricultural sectors are described.