Evaluation of Rainfall Thresholds Through Entropy: Influence of Bivariate Distribution Selection

Ridolfi, Elena; Montesarchio, Valeria; Rianna, M.; Sebastianelli, Stefano; Russo, Fabio; Napolitano, Francesco

doi:10.1002/ird.1807

Cited by 17 publications

(6 citation statements)

References 47 publications

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“…Many researchers define the rainfall threshold as the rainfall amount that, once exceeded, can trigger a critical discharge in a specific river cross-section or basin outlet that causes damage downstream [13,17,36]. This is especially feasible for rural areas while a variety of rainfall-runoff models are helpful to determine the relationship between rainfall and discharge on a catchment scale.…”

Section: Critical Flood Conditionsmentioning

confidence: 99%

An Advanced Method to Apply Multiple Rainfall Thresholds for Urban Flood Warnings

Jang

2015

Water

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Abstract:Issuing warning information to the public when rainfall exceeds given thresholds is a simple and widely-used method to minimize flood risk; however, this method lacks sophistication when compared with hydrodynamic simulation. In this study, an advanced methodology is proposed to improve the warning effectiveness of the rainfall threshold method for urban areas through deterministic-stochastic modeling, without sacrificing simplicity and efficiency. With regards to flooding mechanisms, rainfall thresholds of different durations are divided into two groups accounting for flooding caused by drainage overload and disastrous runoff, which help in grading the warning level in terms of emergency and severity when the two are observed together. A flood warning is then classified into four levels distinguished by green, yellow, orange, and red lights in ascending order of priority that indicate the required measures, from standby, flood defense, evacuation to rescue, respectively. The proposed methodology is tested according to 22 historical events in the last 10 years for 252 urbanized townships in Taiwan. The results show satisfactory accuracy in predicting the occurrence and timing of flooding, with a logical warning time series for taking progressive measures. For systems with multiple rainfall thresholds already in place, the methodology can be used to ensure better application of rainfall thresholds in urban flood warnings.

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Section: Critical Flood Conditionsmentioning

confidence: 99%

An Advanced Method to Apply Multiple Rainfall Thresholds for Urban Flood Warnings

Jang

2015

Water

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“…In the field of rainfallrunoff analysis, Pechlivanidis et al (2010) proposed an entropy-based measure for the rainfall-runoff model diagnostic, and Pechlivanidis et al (2012) extended the work evaluating the non-dynamical information contained in streamflow analysis; Montesarchio et al (2011) and Ridolfi et al (2013) defined rainfall threshold values minimizing a risk function based on the entropy concept. Weijs et al (2010) proposed a theoretical framework based on relative entropy involving the analysis of a divergence score measure to evaluate the quality of hydrological forecasts.…”

Section: Introductionmentioning

confidence: 99%

An entropy approach for the optimization of cross-section spacing for river modelling

Ridolfi

Alfonso

Baldassarre

et al. 2013

Hydrological Sciences Journal

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An accurate definition of river geometry is essential to implement one-dimensional (1D) hydraulic models and, in particular, appropriate spacing between cross-sections is key for capturing a river's hydraulic behaviour. This work explores the potential of an entropy-based approach, as a complementary method to existing guidelines, to determine the optimal number of cross-sections to support 1D hydraulic modelling. To this end, given a redundant collection of existing cross-sections, a location subset is selected minimizing total correlation (as a measure of redundancy) and maximizing joint entropy (as a measure of information content). The problem is posed as a multiobjective optimization problem and solved using a genetic algorithm: the Non-dominated Sorting Genetic Algorithm (NSGA)-II. The proposed method is applied to a river reach of the Po River (Italy) and compared to standard guidelines for 1D hydraulic modelling. Cross-sections selected through the proposed methodology were found to provide an accurate description of the flood water profile, while optimizing computational efficiency.Key words cross-sections; heuristic entropy; hydraulic modelling; one-dimensional flow; network optimization; genetic algorithm; NGSA-II Une approche fondée sur l'entropie pour l'optimisation de l'espacement entre sections en travers pour la modélisation en riviére Résumé Une définition précise de la géométrie de la riviére est essentielle pour mettre en oeuvre des modéles hydrauliques unidimensionnels (1D). L'espacement approprié entre les sections en travers de la riviére est un élément clé pour reproduire son comportement hydraulique. Ce travail a pour objectif de fournir une méthode se basant sur l'entropie, complémentaire des guides existants et permettant de fournir des informations supplémentaires pour l'optimisation des modéles hydrauliques 1D et la gestion des jeux de données sur les sections en travers. Plus spécifiquement, sur la base d'une collecte redondante de sites de sections en travers existantes, un sous-ensemble de sites est sélectionné en minimisant la corrélation totale (comme mesure de redondance) et en maximisant l'entropie conjointe (comme mesure du contenu en information). Le probléme est posé sous la forme d'une optimisation multi-objectif, résolue en utilisant un algorithme génétique (NSGA-II). Nous appliquons la méthode proposée aux données de sections en travers sur le Po, en Italie, et nous la comparons aux méthodes existantes en utilisant un modéle hydraulique 1D. Les jeux de sections en travers sélectionnées par la méthodologie proposée fournissent une description précise du profil des eaux en crue, tout en optimisant l'efficacité de calcul.Mots clefs sections en travers ; entropie heuristique ; modélisation hydraulique ; flux unidimensionnel ; optimisation de réseau, algorithme génétique ; NGSA-II 126

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“…Therefore, it is necessary to assess which areas would be flooded considering different regulation strategies of the dam to define suitable operative procedures needed to raise citizens' awareness and thus increase their preparedness to face the flood risk. Moreover, the evaluation of the areas that would be flooded considering different dam regulation strategies is of great importance to plan non-structural mitigation strategies such as early warning systems [19,20].…”

Section: The Plan For the Prevention And Protection From Hydrogeologimentioning

confidence: 99%

Coping with Extreme Events: Effect of Different Reservoir Operation Strategies on Flood Inundation Maps

Ridolfi

Francesco

Pandolfo

et al. 2019

Water

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The need of addressing “residual flood risk” associated with structural protection measures, such as levee systems and flood-control reservoirs, has fostered actions aimed at increasing flood risk awareness. Structural measures have lowered risk perception by inducing a false sense of safety. As a result, these structures contribute to an underestimation of the “residual risk”. We analyze the effect of different reservoir operations, such as coping with drought versus coping with flood events, on flood inundation patterns. First, a hydrological model simulates different scenarios, which represent the dam regulation strategies. Each regulation strategy is the combination of an opening of the outlet gate and of the initial water level in the reservoir. Second, the corresponding outputs of the dam in terms of maximum discharge values are estimated. Then, in turn, each output of the dam is used as an upstream boundary condition of a hydraulic model used to simulate the flood propagation and the inundation processes in the river reach. The hydraulic model is thus used to determine the effect, in terms of inundated areas, of each dam regulation scenario. Finally, the ensemble of all flood inundation maps is built to define the areas more prone to be flooded. The test site is the Casanuova dam (Umbria, central Italy) which aims at: (i) mitigating floods occurring at the Chiascio River, one of the main tributaries of Tiber River, while (ii) providing water supply for irrigation. Because of these two competitive interests, the understanding of different scenarios generated by the dam operations offers an unique support to flood mitigation strategies. Results can lead to draw interesting remarks for a wide number of case studies.

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Evaluation of Rainfall Thresholds Through Entropy: Influence of Bivariate Distribution Selection

Cited by 17 publications

References 47 publications

An Advanced Method to Apply Multiple Rainfall Thresholds for Urban Flood Warnings

An Advanced Method to Apply Multiple Rainfall Thresholds for Urban Flood Warnings

An entropy approach for the optimization of cross-section spacing for river modelling

Coping with Extreme Events: Effect of Different Reservoir Operation Strategies on Flood Inundation Maps

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