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- Montesarchio, Valeria, et al.
(author)
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A comparison of two rainfall disaggregation models
- 2012
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In: AIP Conference Proceedings. - : American Institute of Physics (AIP). - 0094-243X.
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Conference paper (peer-reviewed)abstract
- Whitin the context of flood management, and generally for performing environmental, climate, hydrological, and water resources analysis, it is useful and reliable to provide scenarios by rainfall simulation, in order to overcome data limitations in terms of time and spatial resolution. Generally, it is required that the stochastic model preservesimportant properties of the rainfall process, such as intermittency, seasonality and scaling behavior in space and time, so that there will be no substantial differences between historical rainfall data and synthetic records. In this work, two rainfall disaggregation models are evaluated in terms of their ability to reproduce rainfall hourly statistics in four sites in Central Italy. The considered models are an entropy based disaggregation model and Hyetos-R (Bartlett-Lewis rectangular pulses rainfall)
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2. |
- Montesarchio, Valeria, et al.
(author)
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Comparison of methodologies for flood rainfall thresholds estimation
- 2015
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In: Natural Hazards. - : Springer Netherlands. - 0921-030X .- 1573-0840. ; 75:1, s. 909-934
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Journal article (peer-reviewed)abstract
- A flood warning system based on rainfall thresholds makes it possible to issue alarms via an off-line approach. This technique is useful for mitigating the effects of flooding in small-to-medium-sized basins characterized by an extremely rapid response to rainfall. Rainfall threshold values specify the amount of precipitation that occurs over a given period of time and are dependent on both the amount of soil moisture and the spatiotemporal distribution of the rainfall. The precipitation generates a critical discharge in a particular river cross section. Exceeding these values can produce a critical situation in river sites that make them susceptible to flooding. In this work, we present a comparison of methodologies for estimating rainfall thresholds. Critical precipitation amounts are evaluated using empirical data, hydrological simulations and probabilistic methods. The study focuses on three small-to-medium-sized basins located in central Italy. For each catchment, historical data are first used to theoretically evaluate the empirical rainfall thresholds. Next, we calibrate a semi-distributed hydrological model that is validated using rain gauge and weather radar data. Critical rainfall depths over 30 min and 1, 3, 6, 12 and 24 h durations are then evaluated using the hydrological simulation. In the probabilistic approach, rainfall threshold values result from a minimization of two different functions, one following the Bayesian decision theory and the other following the informative entropy concept. In order to implement both functions, it is necessary to evaluate the joint probability function. The joint probability function is built up as a bivariate distribution of rainfall depth for a given duration with the corresponding flow peak value. Finally, in order to assess the performance of each methodology, we construct contingency tables to highlight the system performance.
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3. |
- Montesarchio, Valeria, et al.
(author)
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Rainfall threshold definition using an entropy decision approach and radar data
- 2012
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In: Natural hazards and earth system sciences. - : Copernicus GmbH. - 1561-8633 .- 1684-9981. ; 7, s. 2061-2074
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Journal article (peer-reviewed)abstract
- Flash flood events are floods characterised by a very rapid response of basins to storms, often resulting in loss of life and property damage. Due to the specific space-time scale of this type of flood, the lead time available for triggering civil protection measures is typically short. Rainfall threshold values specify the amount of precipitation for a given duration that generates a critical discharge in a given river cross section. If the threshold values are exceeded, it can produce a critical situation in river sites exposed to alluvial risk. It is therefore possible to directly compare the observed or forecasted precipitation with critical reference values, without running online real-time forecasting systems. The focus of this study is the Mignone River basin, located in Central Italy. The critical rainfall threshold values are evaluated by minimising a utility function based on the informative entropy concept and by using a simulation approach based on radar data. The study concludes with a system performance analysis, in terms of correctly issued warnings, false alarms and missed alarms.
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4. |
- Ridolfi, Elena, et al.
(author)
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An entropy approach for evaluating the maximum information content achievable by an urban rainfall network
- 2011
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In: Natural hazards and earth system sciences. - : Copernicus GmbH. - 1561-8633 .- 1684-9981. ; 11:7, s. 2075-2083
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Journal article (peer-reviewed)abstract
- Hydrological models are the basis of operational flood-forecasting systems. The accuracy of these models is strongly dependent on the quality and quantity of the input information represented by rainfall height. Finer space-time rainfall resolution results in more accurate hazard forecasting. In this framework, an optimum raingauge network is essential in predicting flood events.This paper develops an entropy-based approach to evaluate the maximum information content achievable by a rainfall network for different sampling time intervals. The procedure is based on the determination of the coefficients of transferred and nontransferred information and on the relative isoinformation contours.The nontransferred information value achieved by the whole network is strictly dependent on the sampling time intervals considered. An empirical curve is defined, to assess the objective of the research: the nontransferred information value is plotted versus the associated sampling time on a semi-log scale. The curve has a linear trend.In this paper, the methodology is applied to the high-density raingauge network of the urban area of Rome.
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