Search results for " idrologia"
showing 10 items of 476 documents
Tetti verdi multistrato per lo sviluppo sostenibile di città resilienti: quattro casi studio italiani
2021
Negli ultimi anni le inondazioni in ambito urbano sono state sempre più frequenti, provocando notevoli danni sia livello sociale che a livello economico. Questo fenomeno è in parte determinato da un aumento di urbanizzazione causato dalla crescita della popolazione, che tende sempre più a spostarsi dalle zone rurali alle aree urbane, che si espandono molto velocemente, spesso con infrastrutture idrauliche inadeguate. Inoltre, a causa di cambiamenti climatici, soprattutto nelle aree mediterranee, si può osservare un aumento di lunghi periodi di siccità, intervallati da piogge di breve durata, ma di sempre più forte intensità e frequenza. La presenza di questi fenomeni di pioggia intensa, in …
DORA algorithm for network flow models with improved stability and convergence properties
2001
A new methodology for the solution of shallow water equations is applied for the computation of the unsteady-state flow in an urban drainage network. The inertial terms are neglected in the momentum equations and the solution is decoupled into one kinematic and one diffusive component. After a short presentation of the DORA (Double ORder Approximation) methodology in the case of a single open channel, the new methodology is applied to the case of a sewer network. The transition from partial to full section and vice versa is treated without the help of the Preissmann approximation. The algorithm also allows the computation of the diffusive component in the case of vertical topographic discon…
Daily streamlow prediction with uncertainty in ephemeral catchments using the GLUE methodology
2009
Abstract The Generalised Likelihood Uncertainty Estimation (GLUE) approach is presented here as a tool for estimating the predictive uncertainty of a rainfall–runoff model. The GLUE methodology allows to recognise the possible equifinality of different parameter sets and assesses the likelihood of a parameters set being acceptable simulator when model predictions are compared to observed field data. The results of the GLUE methodology depend greatly on the choice of the likelihood measure and on the choice of the threshold which determines if a parameters set is behavioural or not. Moreover the sampling size has a strong influence on the uncertainty assessment of the response of a rainfall–…
Probabilistic characterization of flood hazard using bivariate analysis based on copulas
2014
This study presents an innovative approach to obtain flood hazard maps where hydrological input (synthetic flood design event) to a 2D hydraulic model has been defined by generating flood peak discharges and volumes from a bivariate statistical analysis, through the use of copulas. Synthetic hydrographs were generated by means two different approaches: an indirect one, where rainfall were generated by a stochastic bivariate rainfall generator to be entered a distributed conceptual rainfall-runoff model that consisted of a soil moisture routine and a flow routing routine; and a direct one, where stochastic generation of flood peaks and flow volumes have been obtained via copulas, which descr…
State and parameter update in a coupled energy/hydrologic balance model using ensemble Kalman filtering
2012
Summary The capability to accurately monitor and describe daily evapotranspiration (ET) in a cost effective manner is generally attributed to hydrological models. However, continuous solution of energy and water balance provides precise estimations only when a detailed knowledge of sub-surface characteristics is available. On the other hand, residual surface energy balance models, based on remote observation of land surface temperature, are characterised by sufficient accuracy, but their applicability is limited by the lack of high frequency and high resolution thermal data. A compromise between these two methodologies is represented by the use of data assimilation scheme to include sparse …
Caratterizzazione idrologica dei bacini siciliani col metodo del Curve Number
2010
RUNOFF CURVE NUMBER METHOD IN SICILY: CN DETERMINATION AND ANALYSIS OF THE INITIAL ABSTRACTION RATIO
2010
The Curve Number method is widely used in hydrology because it’s simply based on a single parameter, CN, that represents the basin absorption. In this paper CN is evaluated at basin scale from rainfall-runoff multi-daily events (Mockus, 1964), in the observation period 1940-1997 (record length mean equal to 20 years), for 61 Sicilian basin with three different methods: NEH4 method, Asymptotic fitting method (Hawkins, 1990, Hawkins et al., 2002, Hawkins et al., 2009), Least squares method (Woodward et al., 2006, Hawkins et al., 2009). A first analysis of Sicilian watershed behavior indicates a major occurrence of standard CN response (42 basins), rather than complacent response (11 basins) a…
Ricostruzione delle curve di durata mediante un nuovo approccio ecoidrologico
2012
Le curve di durata delle portate forniscono un importante sintesi dei processi idrologici più rilevanti occorrenti a scala di bacino. Sebbene vengano tipicamente ottenute a partire dalle osservazioni idrometriche, uno dei temi più rilevanti in idrologia è proprio la loro ricostruzione anche in bacini non strumentati. A tal proposito sono stati sviluppati negli ultimi anni svariati approcci teorici, alcuni dei quali meritano particolare attenzione per la loro semplicità di applicazione e accuratezza dei risultati mostrati. La curva di durata viene spesso disaggregata in due componenti: una componente veloce di deflusso superficiale ed una componente lenta di deflusso subsuperficiale. Un rece…
Ecohydrology in Mediterranean areas: a numerical model to describe growing seasons out of phase with precipitations
2008
The probabilistic description of soil moisture dynamics is a relatively new topic in hydrology. The most common ecohydrological models start from a stochastic differential equation describing the soil water balance, where the unknown quantity, the soil moisture, depends both on spaces and time. Most of the solutions existing in literature are obtained in a probabilistic framework and under steady-state condition; even if this last condition allows the analytical handling of the problem, it has considerably simplified the same problem by subtracting generalities from it. <br><br> The steady-state hypothesis, appears perfectly applicable in arid and semiarid climatic areas like th…
Evaluation of different InSAR multi-baseline construction methods over a dam in southern Italy
2018
Monitoring dam displacements using different techniques allows an evaluation of their structural behaviour over time. In this study, dam displacements (for the Castello dam, Agrigento, Italy) have been investigated using different Interferometric Synthetic Aperture Radar (InSAR) techniques exploiting a freely available dataset from the EU Copernicus Sentinel-1 SAR built by the European Space Agency (ESA). The dataset includes Sentinel 1A (S1A) images acquired in dual-polarization and Interferometric Wide (IW) swath using the Terrain Observation with Progressive Scans SAR (TOPSAR) mode. Three main Multi-Baseline Construction methods based on the identification of Persistent Scatterers (PS) h…