Analysis of Extreme Hydrometeorological Events

Surveys in Geophysics, 1995

During the seasonal time window from late summer to the beginning of the winter period, the typical cyclonic circulation over Europe -with deep atmospheric lows located somewhere over the British Islands or Northern Franceprompts intense flows of humid and unstable air masses from the south of the Mediterranean Sea to impact in the northern rugged topography coastline. As a consequence of such atmospheric conditions short torrents and rivers draining the southern slopes of the Pyrenees, the Alps Maritimes and the Apennines randomly produce flash intense floods which hit the historical towns and cities densely developed along their courses. After several catastrophic rainfall events which have been recently observed over the Mediterranean area need for the development of methods for the assessment of hydrometeorological hazard capable of producing reliable predictions of extreme rainfall leading to disastrous runoff occurrences urgently arises. Operational strategies are especially needed in order to develop early warning systems which may save human lives and reduce economical losses in the regions of concern.

2011

This study's approach is based on the analysis of past Damaging Hydrogeological Events (DHEs), which can be defined as periods characterised by heavy rainfall inducing such damaging phenomena as landslides and floods. The proposed work is focused on the relationships between these phenomena and the characteristics of triggered rainfall, to supply useful suggestions for early detection and damage mitigation. The analysis of past DHEs allows for the characterisation of the main types of DHEs, which affected a selected area in the past and could affect it again in the future. The characterisation is based on triggering scenarios (meteorological conditions preceding the occurrence of DHEs), DHE's effects (damage caused by landslides and floods) and triggering factors (rainfall of different durations). Based on these characteristics, the typical DHEs affecting a study area can be ranked according to their severity, and specific emergency management can be planned to successfully manage them. In order to obtain results that have a reliable statistical meaning, a large amount of data of three different types (meteorological, rainfall and damage data) must be studied, and some indices, allowing the comparative analysis of these kinds of data, have to be introduced. After a description of the methodology, which can be applied in different climatic and anthropogenic contexts, some applications of the proposed method to the region of Calabria (South Italy) are presented.

NATO Science Series, 2007

In this paper an overview is given of the statistical methods which are needed to analyse observed environmetric data with a particular interest for the extreme values. The methods for trend analysis, stationarity tests, seasonality analysis, long-memory studies will be presented, critically reviewed, applied to some existing datasets, and compared.

Advances in Water Resources, 2018

The DISASTER database records 1969 unique hydro-geomorphologic cases (floods and landslides) that generated human damages in Portugal during a 150 year-period (1865-2015. The main purposes of this work are the following: to present a national disaster events catalogue; to analyse the atmospheric conditions and to discuss the role of rainfall as main driving force of the hydro-geomorphological disaster events. The main Circulation Weather Types (CWTs) and the presence of Atmospheric Rivers (ARs) of each day of the disaster events were classified using the 20CR dataset (1865-2014) and the NCEP/NCAR reanalysis (2015). These datasets were used to compute the daily cumulative precipitation and the long term climatological year accumulated precipitation 10th, 50th, 90th and 95th percentile spanning 1865-2015 and the accumulated rainfall conditions after and before each disaster event. In the central and northern Portugal Disaster events are mainly driven by southwest (SW), west (W), northwest (NW) and Cyclonic (C) Weather Types, whereas the CWTs with a southern and eastern component [east (E), southeast (SE) and south (S)] are the main drivers in the south part of the country. Cyclonic CWT is widely associated with convective systems that can generate flash floods and urban floods often responsible for fatalities and injured people. CWTs with a westerly component can be associated to prolonged wet periods that can induce flood events in the main rivers and landslides in the mountain areas. The methodology used to build this disaster event catalogue can be applicable to other study areas, namely the North Atlantic and the Mediterranean regions, where the flood and landslides extremes are related to the atmospheric circulation.

Advances in Geosciences, 2007

Analysis of extreme hydrometeorological events is important for characterizing and better understanding the meteorological conditions that can generate severe rainstorms and the consequent catastrophic flooding. According to several studies (e.g., Alpert et al., 2004; Wittenberg et al., 2007), the occurrence of such extreme events is increasing over the eastern Mediterranean although total rain amounts are generally decreasing. The current study presents an analysis of an extreme event utilizing different methodologies: (a) synoptic maps and high resolution satellite imagery for atmospheric condition analysis; (b) rainfall analysis by rain gauges data; (c) meteorological radar rainfall calibration and analysis; (d) field measurements for estimating maximum peak discharges; and, (e) high resolution aerial photographs together with field surveying for quantifying the geomorphic impacts. The unusual storm occurred over Israel between 30 March and 2 April, 2006. Heavy rainfall produced more than 100 mm in some locations in only few hours and more than 200 mm in the major core area. Extreme rain intensities with recurrence intervals of more than 100 years were found for durations of 1 h and more as well as for the daily rain depth values. In the most severely affected area, Wadi Ara, extreme flash floods caused damages and casualties. Specific peak discharges were as high as 10-30 m³/s/km² for catchments of the size of 1-10 km², values larger than any recorded floods in similar climatic regions in Israel.

DESALINATION AND WATER TREATMENT, 2020

There has been in recent years an increase in interest and concerns about natural disasters, both in the scientific community and the society, in relation to their frequency and intensity, the association to global warming, and cyclones (hurricanes and medicanes). In this work, two environmental hydrodynamics models are presented. The first model is built for Hurricane Irma that took place in 2017 in the Caribbean and the second for medicane Zorba that took place in 2018 in the Mediterranean Sea. The models were developed using downscaling techniques on the MOHID platform (a free open model developed for hydrodynamic solution). Water surface currents results are presented for regions of interest together with water level variations in Virtual Maregraphic Stations, "Isabella de Sagua" at Sagua de la Grande in Cuba, Key West in USA, Katacolon and "Kalamai" in Greece, all of them located in the trajectory of both cyclones. Promising results on the modeling of the interaction between water and the atmosphere aligned with available open-source data demonstrate the accuracy of inverse problem-based solutions for natural disaster modeling and its potential for drift simulation of floating objects in future studies.

2009

2011

This Special Issue reports on recent work related to extreme events. It focuses on research related to the EuropeanCommission–supported project “Extreme Events: Causes and Consequences” (E2C2). E2C2 investigated various methodologies for the study of extreme events and their applications to several areas of the geosciences in which such events occur. The strength of the project – which included 17 partners in nine countries – was to bring together a number of usually disparate communities, from statistics, climate science, geophysics, economy and sociology. The results of the E2C2 project already include over 100 papers published in a number of journals in different fields. This Special Issue collects in a unified setting 13 representative research papers related to extreme-event research, complemented by an overall review paper, with the purpose of highlighting the project’s combined impact on the field. In March 2005, when this 3.5-yr project started, events like the storms Lothar...