1,721,021 research outputs found
GRID computing approach for multireservoir operating rules with uncertainty
No full textDeveloping mathematical optimization models that define multireservoir operating rules that are
worthy of being evaluated by simulation models is a challenging task. The traditional approach can easily
be scaled, and GRID computing can reduce computation times for large water resource systems. The
potential for GRID computing in this area of research is largely unexplored. In this paper, the migration of
a mixed optimization–simulation approach and preliminary applications to a water system in Southern
Italy are presented. Results indicate that GRID computing provides significant savings in computation
time
Improved Implicit Stochastic Optimization technique for multireservoir water systems under drought conditions
No full textDrought is a creeping phenomenon, making its onset and end difficult to determine. Damages from droughts can exceed those resulting from any other natural hazard, although it is difficult to assign a monetary value to them. In the Mediterranean area a severe drought period occurred over the years 2000-2002 and economic losses from that drought exceeded 250 million euros in Sardinia (Italy) (source: ENAS Regional Water Authority). Currently, technological developments and environmental modelling tools are improving our ability to more effectively manage water supply systems. Models can provide decision makers with better and more timely data and information. In this paper a methodology is proposed to support water decisions by selecting and evaluating reservoir operating rules based on hydrological scenarios generated from historical records. The methodology includes optimization and simulation tools. In particular, the paper presents some improvements to the traditional Implicit Stochastic Optimization (ISO) approach that overcome some severe limitations affecting previous works. Thanks to the collaboration with Regional Water Authorities in Southern Italy, the proposed methodology has been tested in the Agri-Sinni water system. Specifically this investigation focuses on: 1) Defining the reservoir operating rules based on correlations between releases, storages and inflows in a risk management approach of drought events; 2) Analyzing the significant reduction of computational time the user can get by applying the ISO technique in a GRID computing approach
Morphological response of a sandy shoreline to a natural obstacle at Sa Mesa Longa Beach, Italy
No full textA case study is presented of a comprehensive analysis of the shoreline stability of a salient (primary response) in the lee of an emergent natural reef at Sa Mesa Longa Beach, Sardinia, Italy. The analysis combines sources of information at different levels of detail and accuracy: field surveys conducted with a GPS unit, remotely sensed imagery, geometrical and shape predictive formulas, and simulations with a 2D wave/current/sediment transport numerical model. The morphological simulation results for the primary response agree qualitatively with field observations and predictions from empirical formulas. The accuracy of a simplified wave energy model in defining the littoral sediment cell compared to the more detailed results of the morphological model is also investigated. Although the analysis has some limitations, as highlighted in the paper, the results appear to be promising in terms of applying the analysis to fragile morphologies in the lee of natural reefs in the Mediterranean Sea
Morphology of the salient of tuerredda beach (Sardinia, Italy) and hydrodynamic along the shoreline
No full textOn sandy shores, offshore obstacles create wider beaches, termed salients and tombolos, due to sediment deposition in their lee. The Authors quantified the shape and dimensions of salients formed in the lee of a natural reef and island in south Sardinia (Italy) and found that morphological results were in good agreement with previous investigations through aerial photographs of the coastlines of south eastern Australia and new Zeeland. This paper presents some preliminary results on the salient morphology and complex hydrodynamic behaviour near an island. The beach investigated in this work, known as the Tuerredda beach, is located in the south coast of Sardinia, the shoreline being characterised in the central part by a salient-shape due to the homonymous island. It is expected that the shoreline would be complex in its evolution over time due to the high variability of wave-induced currents and the random instability of the near natural mouth of a seasonally ephemeral stream
Field measurements of tug waves in the Cagliari Harbor, Italy
No full textField measurements of ship-generated waves were performed in the Cagliari Harbor where tugboats are significant wave generators that can adversely affect small-sized moored vessels. A method is proposed in which the major characteristics of the ship-generated waves in areas where wind waves and swell occur can be assessed and presented. The requirements and limitations of the method are also discussed. The results of the method application to field data were compared to an extensively used empirical equation from the literature for the prediction of the maximum wave height generated by tug passages. Although this comparison was affected by the uncertainties in the formation and propagation of ship-generated waves, it confirmed the practical validity of the proposed method
UNA TECNICA MISTA DI OTTIMIZZAZIONE E SIMULAZIONE PER LA PIANIFICAZIONE DELLE AZIONI DI MITIGAZIONE DELLA SICCITÀ: APPLICAZIONE AL SISTEMA AGRI-SINNI
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