Search results for " extremes"
showing 6 items of 6 documents
Individuazione dei trend di pioggia per la Sicilia utilizzando un approccio multiscala basato sulla regressione a quantili
2021
Uno degli argomenti più attuali e controversi è se, negli ultimi decenni, le piogge intense siano diventate più frequenti come possibile effetto dei cambiamenti climatici. La centralità del tema è giustificata dalle gravi conseguenze che l’intensificarsi di questi fenomeni, in frequenza e magnitudo, potrebbe indurre a livello sociale ed economico. Basti pensare alle “flash flood”, spesso causate da eventi di precipitazione con una forte componente convettiva, che in ambito urbano mettono in crisi i sistemi di drenaggio arrecando rilevanti danni e, purtroppo, anche perdite di vite umane. La Sicilia è stata spesso monitorata con l’obiettivo di individuare delle mutazioni significative del cic…
Effects of climate and land use changes on runoff extremes
2017
The analysis of the hydrological changes and their interacting triggering factors are objectives defined within the Panta Rhei decade 2013-2022. Climate change and urbanization are among the most recurrent causes for hydrological changes at the global level. This work proposes a modeling framework for the analysis of the alterations in the watershed hydrological response and, more specifically, in runoff extremes, induced by such perturbations. A weather generator and a cellular automata land-use change model are used to generate hypothetical scenarios accounting for relevant trends at the global level. Such scenarios are successively considered to force a physically-based and spatial-distr…
Non-crossing parametric quantile functions: an application to extreme temperatures
2019
Quantile regression can be used to obtain a non-parametric estimate of a conditional quantile function. The presence of quantile crossing, however, leads to an invalid distribution of the response and makes it difficult to use the fitted model for prediction. In this work, we show that crossing can be alleviated by modelling the quantile function parametrically. We then describe an algorithm for constrained optimisation that can be used to estimate parametric quantile functions with the noncrossing property. We investigate climate change by modelling the long-term trends of extreme temperatures in the Arctic Circle.
Combined effects of heatwaves and micropollutants on freshwater ecosystems: Towards an integrated assessment of extreme events in multiple stressors …
2022
Freshwater ecosystems are strongly influenced by weather extremes such as heatwaves, which are predicted to increase in frequency and magnitude in the future. In addition to these climate extremes, the freshwater realm is impacted by the exposure to various classes of chemicals emitted by anthropogenic activities. Currently, there is limited knowledge on how the combined exposure to heatwaves and chemicals affects the structure and functioning of freshwater ecosystems. Here, we review the available literature describing the single and combined effects of heatwaves and chemicals on different levels of biological organization, to obtain a holistic view of their potential interactive effects. …
Regional frequency analysis of extreme precipitation for Sicily (Italy)
2016
The analysis of extreme precipitation has always been included among most relevant hydrological applications because of the several important activities linked to the availability of tools for the estimation of extreme rainfall quantiles. These activities include the design of hydraulic civil structures and the evaluation and management of hydraulic and hydrological risk. In this study a frequency analysis of annual maxima precipitation measurements has been carried out for the area of Sicily (Italy). A typical hierarchical regional approach has been adopted for the parameter estimation procedure based on the L-moments method. The identification of homogeneous regions within the procedure h…
Detecting precipitation trend using a multiscale approach based on quantile regression over a Mediterranean area
2021
One of the most relevant and debated topics related to the effects of the climate change is whether intense rainfall events have become more frequent over the last decades. It is a crucial aspect, since an increase in the magnitude and frequency of occurrence of heavy rainfall events could result in a dramatic growth of floods and, in turn, human lives losses and economic damages. Because of its central position in the Mediterranean area, Sicily has been often screened with the aim to capture some trends in precipitation, potentially related to climate change. While Mann-Kendall test has been largely used for the rainfall trend detection, in this work a different procedure is considered. Pr…