Weather circulation patterns as precursor of heavy rainfall events: an application to Sicily, Italy

Since the impacts of climate change on the environment have been constantly rising over the last decades, scientists have paid much attention to understanding the effects of this phenomenon. Climate change leads to different kinds of extremes, such as heavy rainfall events, characterized by short duration and high intensity, and drought, which can cause the problem of water scarcity over a certain area. These types of extreme events cause several damages for the affected areas since they can result in loss of human lives and economic damages. In particular, heavy rainfall events, which are often associated with convective precipitation because of their characteristics, may result in flash f…

Using an X-band radar for an urban area early flood warning system

Floods represent a serious hazard in many areas of the world in terms of damage to properties and loss of life. For this reason, the European Floods Directive 2007/60/EC on the assessment and management of flood risk required the relevant bodies of the Member States to have adequate and efficient tools for assessing the flood risk of river basins and establishing flood risk management plans focused on prevention and protection of territory and people. The decision makers involved in flood defense often need some hydro-informatics tools to transform the flood forecast into relatively simple and clear messages that allow them to take prompt action to prevent and/or counteract the flood. From …

Effects of climate and land use changes on runoff extremes

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…

Studying the relationships between hourly precipitation extremes and dewpoint temperature in Sicily.

According to the well-known Clausius-Clapeyron relation, the maximum moisture content of the atmosphere increases with approximately 7% per degree temperature raise (CC-scaling rate). Under the hypothesis that relative humidity does not change, an increase in the water vapor should occur at the same rate. For this reason we could expect for the coming years an increase in the intensity of extreme precipitation as a consequence of the global climate warming. Trend on precipitation extremes and possible links to changes in atmospheric temperature and moisture are investigated in different parts of the world, and a number of observational studies has exhibited scaling rates that are either hig…

Numerical experiments for defining criteria for the use of LS-PIV based techniques in river monitoring.

The developing of new image-based techniques for environmental monitoring is opening new frontiers for remote streamflow measurements in natural environments, since they allow for non-intrusive measurements even in adverse circumstances, such as high flow conditions that often hinder the use of traditional approaches and instruments. Methods based on the acquisition, analysis and elaboration of images for streamflow observation, such as the large scale particle image velocimetry (LSPIV) and the particle tracking velocimetry (PTV) techniques, are rapidly evolving also in consideration of the growing availability of a new generation of optical sensors, digital cameras and methodologies. A num…

Rainfall depth-duration-frequency curves for short-duration precipitation events in Sicily (Italy)

The design criteria of the hydraulic infrastructures, including, for instance, those for flood defense, urban drainage systems, reservoirs spillways and bridges, are based on the coupled analysis of the magnitude of rainfall events for a fixed duration and their estimated annual exceedance probability. The well-known rainfall depth-duration-frequency (DDF) curves, typically derived from the analysis of long historical annual maxima data series, synthesize the relationships between rainfall depth, duration and exceedance probability which is usually expressed as a return period. The time-resolution of rainfall data typically available for the construction of DDF curves and provided by gauges…

Estimating additional root cohesion by exploiting a root topological model based on Leonardo’s Rule

Root topological models are schematic representations of the root structure based on a defined topology graph theory. In the context of hillslope stabilization modeling against rainfall-induced shallow landslides, the root topological models may be used in combination with root strength models assessment, such as the Root Bundle Model (RBM), to estimate the ultimate root reinforcement. The effect of plant roots on slope stabilization is determined by the interaction between soil and the hydrological processes (within the root zone) and the biotechnical characteristics of the root system, such as root length, root density, root tensile strength, root area, root diameter profile and the total…

Precipitazione e pattern di circolazione atmosferica in Sicilia

Gli eventi di precipitazione intensa possono spesso causare perdita di vite umane e ingenti danni di tipo economico, soprattutto nei casi in cui questi colpiscano piccoli bacini caratterizzati da bassi tempi di corrivazione. Dal momento che alcuni schemi di circolazione atmosferica comportano un accumulo di umidità in certe parti dell’atmosfera, a seguito del quale possono scatenarsi eventi di particolare entità, la circolazione atmosferica può essere utilizzata come un indicatore del verificarsi di eventi di precipitazione intensa. Nel presente lavoro si è cercato di trovare una relazione tra alcuni pattern di circolazione atmosferica, sviluppati dal UK Met Office, e i massimi annuali di p…

Convective and stratiform precipitation: A PCA-based clustering algorithm for their identification

The increasing occurrence of flood events in some areas of the Southern Mediterranean area (e.g., Sicily), over the last few years, has contributed to raising the importance of characterizing such events and identifying their causes.

Propagation of precipitation measurement biases into the hydraulic modelling of urban drainage systems – A case study of the Parco D’Orleans sub-urban catchment

Aim of this study is to evaluate the impact of Precipitation Measurement Biases (PMBs) of tippingbucket rain gauges onto the hydraulic modelling of urban drainage networks. As a case study, the monitored experimental suburban catchment of Parco d’Orleans located in the University Campus of Palermo, Italy and managed since 1987 by the Department of Engineering of the University of Palermo is considered. . Two tipping-bucket rain gauges provide a good spatial coverage of the catchment area and an acoustic level gauge is installed at the outlet of the drainage network for flow mesaurements. Contemporary high temporal resolution rainfall and runoff data series are available between 1993 to 1998…

DEM-resolution control on rainfall-triggered landslide modeling within a triangulated network-based model

Catchment slope distribution significantly controls rainfall-triggered landslide modeling, in both direct and indirect ways. Slope directly determines the soil volume associated with instability. Indirectly, it affects the subsurface lateral redistribution of soil moisture across the basin, which in turn determines the water pore pressure conditions that impact slope stability. It is thus clear that the accuracy in reproducing slope distribution may be crucial in slope stability analysis. The resolution of the Digital Elevation Model (DEM) regulates the description of the topography. The correlation between raster resolution and landslide model outputs has been investigated in the literatur…

Utilizzo di tecniche di machine learning e previsioni stagionali per la stima dei volumi di invaso

Influenza del cambiamento climatico e dell’urbanizzazione sull’idrologia dei bacini idrografici

I cambiamenti climatici e il fenomeno del consumo del suolo sono senz’altro i fattori che più influenzano la risposta idrologica di un bacino sia in contesti urbani che extraurbani. L’aumento del grado di urbanizzazione dei bacini naturali, inteso come aumento della frazione impermeabile del suolo derivante della costante copertura di aree del bacino con materiali impermeabili artificiali come asfalto e cemento, è un fenomeno in costante crescita a livello globale. A tali cambiamenti si sovrappongono i cambiamenti climatici in atto che, fra gli effetti principali, tendono a modificare la quantità e la modalità con cui le piogge arrivano al suolo e, al contempo, inducono alterazioni al regim…