1,720,979 research outputs found
Geomorphic classifiers for flood-prone areas delineation for data-scarce environments
No full textKnowing the location and the extent of the areas exposed to flood hazards is essential to any strategy for minimizing the risk. Unfortunately, in ungauged basins the use of traditional floodplain mapping techniques is prevented by the lack of the extensive data required. The present work aims to overcome this limitation by defining an alternative simplified procedure for a preliminary floodplain delineation based on the use of geomorphic classifiers. To validate the method in a data-rich environment, eleven flood-related morphological descriptors derived from remotely sensed elevation data have been used as linear binary classifiers over the Ohio River basin and its sub-catchments. Their performances have been measured at the change of the topography and the size of the calibration area, allowing to explore the transferability of the calibrated parameters, and to define the minimum extent of the calibration area. The best performing classifiers among those analysed have been applied and validated across the continental U.S. The results suggest that the classifier based on the Geomorphic Flood Index (GFI), is the most suitable to detect the flood-prone areas in data-scarce regions and for large-scale applications, providing good accuracies with low requirements in terms of data and computational costs. This index is defined as the logarithm of the ratio between the water depth in the element of the river network closest to the point under exam (estimated using a hydraulic scaling function based on contributing area) and the elevation difference between these two points
Dataset of 100-year flood susceptibility maps for the continental U.S. derived with a geomorphic method
Full text linkEfficient strategies for preparing communities to protect against, respond to, recover from, and mitigate flood hazard are often hampered by the lack of information about the position and extent of flood-prone areas. Hydrologic and hydraulic analyses allow to obtain detailed flood hazard maps, but are a computationally intensive exercise requiring a significant amount of input data, which are rarely available both in developing and developed countries. As a consequence, even in data-rich environments, official flood hazard graduations are often affected by extensive gaps. In the U.S., for instance, the detailed floodplain delineation produced by the Federal Emergency Management Agency (FEMA) is incomplete, with many counties having no floodplain mapping at all. In this article we present a mapping dataset containing 100-year flood susceptibility maps for the continental U.S. with a 90 m resolution. They have been obtained performing a linear binary classification based on the Geomorphic Flood Index (GFI). To the best knowledge of the authors, there are no available flood-prone areas maps for the entire continental U.S. with resolution lower that 30׳׳×30׳׳ (approximatively 1 km at the equator)
Stima delle aree inondabili mediante metodi geomorfologici e modellazione idraulica mono e bi-dimensionale: applicazione al Fiume Bradano
Full text linkL’individuazione delle aree inondabili è un problema cruciale che, col passare del tempo, sta diventando sempre più impattante sulla nostra società. Una delimitazione preliminare può essere effettuata mediante procedure basate sull’analisi della geomorfo-logia del bacino, la quale può essere ricavata da un DEM di sufficiente risoluzione. Nel presente lavoro, la mappatura delle aree inondabili viene condotta utilizzando tecniche di classificazione binaria lineare basate sui descrittori geomorfologici che hanno un ruo-lo di controllo sul processo di inondazione. I risultati ottenuti possono contribuire alla definizione di nuove strategie per la delimitazione di aree a rischio di inondazione con procedure basate sui DEM. A tal fine sono prese in considerazione alcune caratteristiche locali, generalmente utilizzate per descrivere le caratteristiche idrologiche del bacino, e alcuni indici morfologici compositi, allo scopo di individuare quello più significativo. Le analisi sono effettuate su due diverse serie di dati: una basata su simulazioni idrauliche realizzate con un modello 1-D, e la seconda ottenuta attraverso un modello idraulico 2-D. I risultati evidenziano il potenziale di ogni descrittore morfologico per individuare l'estensione delle aree a rischio d’inondazione e, in particolare, la capacità di un indice geomorfologico di rappresentare le aree inondabili a diverse scale di appli-cazione
Flood-Prone Areas Assessment Using Linear Binary Classifiers based on Morphological Indices
No full textThe identification of flood-prone areas is a critical issue becoming everyday more pressing for our society. A preliminary delineation can be carried out by DEM-based procedures that relay on basin geomorphologic features. In the present paper, we investigated the dominant topographic controls for the flood exposure using techniques of pattern classification through linear binary classifiers based on DEM derived morphologic features. With this aim, local features - which are generally used to describe the hydrological characteristics of a basin - and composite morphological indices are taken into account in order to identify the most significant one. The analyses highlight the potential of each morphological descriptor for the identification of the extend of flood-prone areas. Our findings may help the definition of new strategies for the delineation of flood-prone areas with DEM-based procedures
A GIS tool for cost-effective delineation of flood-prone areas
No full textDelineation of flood hazard and flood risk areas is a critical issue, but practical difficulties regularly make complete achievement of the task a challenge. In data-scarce environments (e.g. ungauged basins, large-scale analyses), useful information about flood hazard exposure can be obtained using geomorphic methods. In order to advance this field of research, we implemented in the QGIS environment an automated DEM-based procedure that exhibited high accuracy and reliability in identifying the flood-prone areas in several test sites located in Europe, the United States and Africa. This tool, named Geomorphic Flood Area tool (GFA tool), enables rapid and cost-effective flood mapping by performing a linear binary classification based on the recently proposed Geomorphic Flood Index (GFI). The GFA tool provides a user-friendly strategy to map flood exposure over large areas. A demonstrative application of the GFA tool is presented in which a detailed flood map was derived for Romania
BRISENT: An entropy-based model for bridge-pier scour estimation under complex hydraulic scenarios
No full textThe goal of this paper is to introduce the first clear-water scour model based on both the informational entropy concept and the principle of maximum entropy, showing that a variational approach is ideal for describing erosional processes under complex situations. The proposed bridge-pier scour entropic (BRISENT) model is capable of reproducing the main dynamics of scour depth evolution under steady hydraulic conditions, step-wise hydrographs, and flood waves. For the calibration process, 266 clear-water scour experiments from 20 precedent studies were considered, where the dimensionless parameters varied widely. Simple formulations are proposed to estimate BRISENT's fitting coefficients, in which the ratio between pier-diameter and sediment-size was the most critical physical characteristic controlling scour model parametrization. A validation process considering highly unsteady and multi-peaked hydrographs was carried out, showing that the proposed BRISENT model reproduces scour evolution with high accuracy
Advances in Large-Scale Flood Monitoring and Detection
Full text linkThe last decades have seen a massive advance in technologies for Earth observation
(EO) and environmental monitoring, which provided scientists and engineers with valuable spatial
information for studying hydrologic processes. At the same time, the power of computers and newly
developed algorithms have grown sharply. Such advances have extended the range of possibilities for
hydrologists, who are trying to exploit these potentials the most, updating and re-inventing the way
hydrologic and hydraulic analyses are carried out. A variety of research fields have progressed
significantly, ranging from the evaluation of water features, to the classification of land-cover,
the identification of river morphology, and the monitoring of extreme flood events. The description of
flood processes may particularly benefit from the integrated use of recent algorithms and monitoring
techniques. In fact, flood exposure and risk over large areas and in scarce data environments have
always been challenging topics due to the limited information available on river basin hydrology,
basin morphology, land cover, and the resulting model uncertainty. The ability of new tools to carry
out intensive analyses over huge datasets allows us to produce flood studies over large extents and
with a growing level of detail. The present Special Issue aims to describe the state-of-the-art on flood
assessment, monitoring, and management using new algorithms, new measurement systems and
EO data. More specifically, we collected a number of contributions dealing with: (1) the impact of
climate change on floods; (2) real time flood forecasting systems; (3) applications of EO data for
hazard, vulnerability, risk mapping, and post-disaster recovery phase; and (4) development of tools
and platforms for assessment and validation of hazard/risk models
Rapid landslide detection from free optical satellite imagery using a robust change detection technique
Full text linkA web application for hydrogeomorphic flood hazard mapping
Full text linkA detailed delineation of flood-prone areas over large regions represents a challenge that cannot be easily solved with today's resources. The main limitations lie in algorithms and hardware, but also costs, scarcity and sparsity of data and our incomplete knowledge of how inundation events occur in different river floodplains. We showcase the implementation of a data-driven web application for regional analyses and detailed (i.e., tens of meters) mapping of floodplains, based on (a) the synthesis of hydrogeomorphic features into a morphological descriptor and (b) its classification to delineate flood-prone areas. We analysed the skill of the descriptor and the performance of the mapping method for European rivers. The web application can be effectively used for delineating flood-prone areas, reproducing the reference flood maps with a classification skill of 88.59% for the 270 major river basins analysed across Europe and 84.23% for the 64 sub-catchments of the Po River
River basins and rural districts: toward a regional planning for Italian watersheds with a broader European view
No full textn spite of the extensive regulations on hydrogeological hazards and the widespread implementation of defence works, the natural fragility of the Italian territory constantly exposes this country to instability phenomena, occurring with regular frequency and causing significant damage to people, structures, and the environment, and compromising the balance of the territorial structure. Within this framework, this chapter presents a series of reflections on how the evolution of a territory due to anthropogenic impact, the increase in climatic variability, and land-use changes can accelerate or mitigate the effects of hydrological extremes. A disaster prevention system, including territorial redevelopment and rehabilitation interventions, should be encouraged not only for environmental protection, but also as an essential element of the country's sustainable socioeconomic development. In this context, an appropriate geographical reference unit is represented by the hydrographic basin, whose analysis is crucial to understanding its predisposition to the different types of instability. The basin also acquires the role of a territorial government unit, at whose scale mitigation measures and damage reduction efforts should be implemented to achieve a rational and coordinated use of the land and of its natural resources, water, and soil. Only an innovative management approach, implemented according to the guidelines suggested by scientific research on agroforestry ecosystems, can provide considerable and lasting benefits to land protection, and at least partially solve the problem of hydrogeological instability
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