scholarly journals Spatiotemporal clustering of flash floods in a changing climate (China, 1950–2015)

2021 ◽  
Vol 21 (7) ◽  
pp. 2109-2124
Author(s):  
Nan Wang ◽  
Luigi Lombardo ◽  
Marj Tonini ◽  
Weiming Cheng ◽  
Liang Guo ◽  
...  
Keyword(s):  
Flash Flood ◽  
Extreme Rainfall ◽  
Flash Floods ◽  
Scan Statistics ◽  
Spatiotemporal Pattern ◽  
Precipitation Trend ◽  
Wet Season ◽  
Extreme Rainfall Events ◽  
Space And Time ◽  
Flood Disasters

Abstract. The persistence over space and time of flash flood disasters – flash floods that have caused either economical losses or loss of life or both – is a diagnostic measure of areas subjected to hydrological risk. The concept of persistence can be assessed via clustering analyses, performed here to analyze the national inventory of flash flood disasters in China that occurred in the period 1950–2015. Specifically, we investigated the spatiotemporal pattern distribution of the flash flood disasters and their clustering behavior by using both global and local methods: the first based on Ripley's K function, and the second on scan statistics. As a result, we could visualize patterns of aggregated events, estimate the cluster duration and make assumptions about their evolution over time, also with respect to the precipitation trend. Due to the large spatial (the whole Chinese territory) and temporal (66 years) scale of the dataset, we were able to capture whether certain clusters gather in specific locations and times but also whether their magnitude tends to increase or decrease. Overall, the eastern regions in China are much more subjected to flash flood disasters compared to the rest of the country. Detected clusters revealed that these phenomena predominantly occur between July and October, a period coinciding with the wet season in China. The number of detected clusters increases with time, but the associated duration drastically decreases in the recent period. This may indicate a change towards triggering mechanisms which are typical of short-duration extreme rainfall events. Finally, being flash flood disasters directly linked to precipitation and their extreme realization, we indirectly assessed whether the magnitude of the trigger itself has also varied through space and time, enabling considerations in the context of climatic change.

scholarly journals Spatiotemporal clustering of flash floods in a changing climate (China, 1950–2015)

2020 ◽  
Author(s):  
Nan Wang ◽  
Luigi Lombardo ◽  
Marj Tonini ◽  
Weiming Cheng ◽  
Liang Guo ◽  
...  
Keyword(s):  
Flash Flood ◽  
Extreme Rainfall ◽  
Flash Floods ◽  
Scan Statistics ◽  
Spatiotemporal Pattern ◽  
Precipitation Trend ◽  
Wet Season ◽  
Extreme Rainfall Events ◽  
Space And Time ◽  
Flood Disasters

Abstract. The persistence over space and time of flash flood disasters – flash floods that have caused either economical or life losses, or both – is a diagnostic measure of areas subjected to hydrological risk. The concept of persistence can be assessed via clustering analyses, performed here to analyse the national inventory of flash flood disasters in China occurred in the period 1950–2015. Specifically, we investigated the spatiotemporal pattern distribution of the flash flood disasters and their clustering behavior by using both global and local methods: the first, based on the Ripley's K-function, and the second on Scan Statistics. As a result, we could visualize patterns of aggregated events, estimate the cluster duration and make assumptions about their evolution over time, also with respect precipitation trend. Due to the large spatial (the whole Chinese territory) and temporal (66 years) scale of the dataset, we were able to capture whether certain clusters gather in specific locations and times, but also whether their magnitude tends to increase or decrease. Overall, the eastern regions in China are much more subjected to flash flood disasters compared to the rest of the country. Detected clusters revealed that these phenomena predominantly occur between July and October, a period coinciding with the wet season in China. The number of detected clusters increases with time, but the associated duration drastically decreases in the recent period. This may indicate a change towards triggering mechanisms which are typical of short-duration extreme rainfall events. Finally, being flash flood disasters directly linked to precipitation and their extreme realization, we indirectly assessed whether the magnitude of the trigger itself has also varied through space and time, enabling considerations in the context of climatic changes.

scholarly journals Recent Advances in Real-Time Pluvial Flash Flood Forecasting

Water ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 570 ◽  
Author(s):  
Andre Zanchetta ◽  
Paulin Coulibaly
Keyword(s):  
Flash Flood ◽  
Low Cost ◽  
Extreme Rainfall ◽  
Early Warning Systems ◽  
Flood Forecasting ◽  
Flash Floods ◽  
Atmospheric Conditions ◽  
Extreme Rainfall Events ◽  
Recent Advances ◽  
Flash Flood Forecasting

Recent years have witnessed considerable developments in multiple fields with the potential to enhance our capability of forecasting pluvial flash floods, one of the most costly environmental hazards in terms of both property damage and loss of life. This work provides a summary and description of recent advances related to insights on atmospheric conditions that precede extreme rainfall events, to the development of monitoring systems of relevant hydrometeorological parameters, and to the operational adoption of weather and hydrological models towards the prediction of flash floods. With the exponential increase of available data and computational power, most of the efforts are being directed towards the improvement of multi-source data blending and assimilation techniques, as well as assembling approaches for uncertainty estimation. For urban environments, in which the need for high-resolution simulations demands computationally expensive systems, query-based approaches have been explored for the timely retrieval of pre-simulated flood inundation forecasts. Within the concept of the Internet of Things, the extensive deployment of low-cost sensors opens opportunities from the perspective of denser monitoring capabilities. However, different environmental conditions and uneven distribution of data and resources usually leads to the adoption of site-specific solutions for flash flood forecasting in the context of early warning systems.

scholarly journals Characteristics of the extreme rainfall event and consequent flash floods in W Slovenia in September 2007

2009 ◽  
Vol 9 (3) ◽  
pp. 947-956 ◽  
Author(s):  
S. Rusjan ◽  
M. Kobold ◽  
M. Mikoš
Keyword(s):  
Flash Flood ◽  
Sampling Error ◽  
Extreme Rainfall ◽  
Weather Forecast ◽  
Flash Floods ◽  
Flood Damage ◽  
Statistical Characteristics ◽  
Extreme Rainfall Event ◽  
Return Periods ◽  
Extreme Rainfall Events

Abstract. During a weather front that passed over large parts of Slovenia on 18.9.2007, extreme rainfall events were triggered causing several severe flash floods with six casualties. Out of 210 municipalities in Slovenia, 60 were reporting flood damages, and the total economic flood damage was later estimated at close to 200 million Euro; highest damage was claimed by Železniki municipality in NW Slovenia. The main purpose of the study presented in this paper was to put together available meteorological and hydrological data in order to get better insight into temporal and spatial dynamics and variability of the flash flood event along the Selška Sora River flowing through the town of Železniki. The weather forecast by the Environmental Agency of the Republic of Slovenia (ARSO) lead to early warning of floodings but has underestimated rainfall amounts by a factor of 2. Also meteorological radar underestimated ground rainfall as much as by 50%. During that day, in many rainfall gauging stations operated by ARSO in the area under investigation, extreme rainfall amounts were measured, e.g. 303 mm in 24 h or 157 mm in 2 h. Some of the measured rainfall amounts were the highest registered amounts in Slovenia so far. Statistical analysis using Gumble distribution was performed and rainfall return periods were estimated. When assessing rainfall return periods, a question of the sampling error as a consequence of short rainfall records used was raised. Furthermore, measured rainfall data were used to reconstruct hydrographs on selected water stations along the Selška Sora River. The cumulative areal precipitation for the Selška Sora River catchment upstream of Železniki amounted to 219 mm, while the modeled effective precipitation used to simulate the hydrograph peak was only 57 mm. The modeled direct runoff coefficient therefore amounts to 0.26. Surprisingly low value is mainly caused by the applied unit hydrograph method that seeks to meet the peak discharge rather than hydrograph volume. However, the spatial distribution of the rainfall in the area was highly variable and present spatial positioning of rain gauges is obviously inadequate for proper representation of the actual spatial amount of rainfall. The study confirmed that post-flood investigation should focus on discharges and hydrological response of the catchment rather than simply analyzing statistical characteristics of rainfall.

scholarly journals Extreme Rainfall in the Mediterranean: What Can We Learn from Observations?

2013 ◽  
Vol 14 (3) ◽  
pp. 906-922 ◽  
Author(s):  
N. Rebora ◽  
L. Molini ◽  
E. Casella ◽  
A. Comellas ◽  
E. Fiori ◽  
...  
Keyword(s):  
Extreme Rainfall ◽  
Flash Floods ◽  
Rain Gauge ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Life Threatening ◽  
The Mediterranean ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Ground Effects

Abstract Flash floods induced by extreme rainfall events represent one of the most life-threatening phenomena in the Mediterranean. While their catastrophic ground effects are well documented by postevent surveys, the extreme rainfall events that generate them are still difficult to observe properly. Being able to collect observations of such events will help scientists to better understand and model these phenomena. The recent flash floods that hit the Liguria region (Italy) between the end of October and beginning of November 2011 give us the opportunity to use the measurements available from a large number of sensors, both ground based and spaceborne, to characterize these events. In this paper, the authors analyze the role of the key ingredients (e.g., unstable air masses, moist low-level jets, steep orography, and a slow-evolving synoptic pattern) for severe rainfall processes over complex orography. For the two Ligurian events, this role has been analyzed through the available observations (e.g., Meteosat Second Generation, Moderate Resolution Imaging Spectroradiometer, the Italian Radar Network mosaic, and the Italian rain gauge network observations). The authors then address the possible role of sea–atmosphere interactions and propose a characterization of these events in terms of their predictability.

scholarly journals Operational tools to help stakeholders to protect and alert municipalities facing uncertainties and changes in karst flash floods

2015 ◽  
Vol 370 ◽  
pp. 201-208 ◽  
Author(s):  
V. Borrell Estupina ◽  
F. Raynaud ◽  
N. Bourgeois ◽  
L. Kong-A-Siou ◽  
L. Collet ◽  
...  
Keyword(s):  
Land Use ◽  
Real Time ◽  
Land Use Changes ◽  
Extreme Rainfall ◽  
Flash Floods ◽  
Uncertain Information ◽  
Extreme Rainfall Events ◽  
Flood Peak ◽  
Planning Decisions ◽  
Graphical Tool

Abstract. Flash floods are often responsible for many deaths and involve many material damages. Regarding Mediterranean karst aquifers, the complexity of connections, between surface and groundwater, as well as weather non-stationarity patterns, increase difficulties in understanding the basins behaviour and thus warning and protecting people. Furthermore, given the recent changes in land use and extreme rainfall events, knowledge of the past floods is no longer sufficient to manage flood risks. Therefore the worst realistic flood that could occur should be considered. Physical and processes-based hydrological models are considered among the best ways to forecast floods under diverse conditions. However, they rarely match with the stakeholders' needs. In fact, the forecasting services, the municipalities, and the civil security have difficulties in running and interpreting data-consuming models in real-time, above all if data are uncertain or non-existent. To face these social and technical difficulties and help stakeholders, this study develops two operational tools derived from these models. These tools aim at planning real-time decisions given little, changing, and uncertain information available, which are: (i) a hydrological graphical tool (abacus) to estimate flood peak discharge from the karst past state and the forecasted but uncertain intense rainfall; (ii) a GIS-based method (MARE) to estimate the potential flooded pathways and areas, accounting for runoff and karst contributions and considering land use changes. Then, outputs of these tools are confronted to past and recent floods and municipalities observations, and the impacts of uncertainties and changes on planning decisions are discussed. The use of these tools on the recent 2014 events demonstrated their reliability and interest for stakeholders. This study was realized on French Mediterranean basins, in close collaboration with the Flood Forecasting Services (SPC Med-Ouest, SCHAPI, municipalities).

Extreme Rainfall Events in the Macro-Metropolis of São Paulo: trends and connection with climate oscillations

2021 ◽  
Author(s):  
Carolyne B. Machado ◽  
Thamiris L. O. B. Campos ◽  
Sameh A. Abou Rafee ◽  
Jorge A. Martins ◽  
Alice M. Grimm ◽  
...  
Keyword(s):  
Urban Areas ◽  
Extreme Rainfall ◽  
Kendall Test ◽  
Rain Gauge ◽  
Sao Paulo ◽  
Annual Rainfall ◽  
São Paulo ◽  
Wet Season ◽  
Extreme Rainfall Events ◽  
Climatic Indices

AbstractIn the present work, the trend of extreme rainfall indices in the Macro-Metropolis of São Paulo (MMSP) was analyzed and correlated with largescale climatic oscillations. A cluster analysis divided a set of rain gauge stations into three homogeneous regions within MMSP, according to the annual cycle of rainfall. The entire MMSP presented an increase in the total annual rainfall, from 1940 to 2016, of 3 mm per year on average, according to Mann-Kendall test. However, there is evidence that the more urbanized areas have a greater increase in the frequency and magnitude of extreme events, while coastal and mountainous areas, and regions outside large urban areas, have increasing rainfall in a better-distributed way throughout the year. The evolution of extreme rainfall (95th percentile) is significantly correlated with climatic indices. In the center-north part of the MMSP, the combination of Pacific Decadal Oscillation (PDO) and Antarctic Oscillation (AAO) explains 45% of the P95th increase during the wet season. In turn, in southern MMSP, the Temperature of South Atlantic (TSA), the AAO, the El Niño South Oscillation (ENSO) and the Multidecadal Oscillation of the North Atlantic (AMO) better explain the increase in extreme rainfall (R2 = 0.47). However, the same is not observed during the dry season, in which the P95th variation was only negatively correlated with the AMO, undergoing a decrease from the ‘70s until the beginning of this century. The occurrence of rainy anomalous months proved to be more frequent and associated with climatic indices than dry months.

scholarly journals The 20 February 2010 Madeira flash-floods: synoptic analysis and extreme rainfall assessment

2012 ◽  
Vol 12 (3) ◽  
pp. 715-730 ◽  
Author(s):  
M. Fragoso ◽  
R. M. Trigo ◽  
J. G. Pinto ◽  
S. Lopes ◽  
A. Lopes ◽  
...  
Keyword(s):  
Return Period ◽  
Flash Flood ◽  
Deep Convection ◽  
Extreme Rainfall ◽  
Flash Floods ◽  
Rain Gauge ◽  
Reanalysis Data ◽  
Sources Of Information ◽  
Precipitation Records ◽  
Flood Dynamics

Abstract. This study aims to characterise the rainfall exceptionality and the meteorological context of the 20 February 2010 flash-floods in Madeira (Portugal). Daily and hourly precipitation records from the available rain-gauge station networks are evaluated in order to reconstitute the temporal evolution of the rainstorm, as its geographic incidence, contributing to understand the flash-flood dynamics and the type and spatial distribution of the associated impacts. The exceptionality of the rainstorm is further confirmed by the return period associated with the daily precipitation registered at the two long-term record stations, with 146.9 mm observed in the city of Funchal and 333.8 mm on the mountain top, corresponding to an estimated return period of approximately 290 yr and 90 yr, respectively. Furthermore, the synoptic associated situation responsible for the flash-floods is analysed using different sources of information, e.g., weather charts, reanalysis data, Meteosat images and radiosounding data, with the focus on two main issues: (1) the dynamical conditions that promoted such anomalous humidity availability over the Madeira region on 20 February 2010 and (2) the uplift mechanism that induced deep convection activity.

Startegic framework for integrated flood Disaster modelling over Bangalore city of India

2021 ◽  
Author(s):  
Smrati Purwar ◽  
Gyanendranath Mohapatra ◽  
Rakesh Vasudevan
Keyword(s):  
Urban Landscape ◽  
Flash Flood ◽  
Warning System ◽  
Extreme Rainfall ◽  
High Elevation ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Bangalore City ◽  
Societal Relevance ◽  
The Impact

<p>Hydro-meteorological disasters, particularly the extreme rainfall events (EREs) and associated flash floods, are very frequent in the major metro cities in India during recent years and in many occasions they cause massive destruction to life and property which in long run make adverse socio-economic impacts over the country. Hence, it makes formost importance and has great societal relevance to modellers working such area to develop an advance prediction system for such disasters in India.A strategic framework combining modelling and data analytics is integral part of developing advanced warning system for preparedness during such disasters. In this study, the role of landuse/landcover like built-up, vegetation, barrenland and waterbodies over the Bangalore city in flash flood occurrence is examined using multispectral spatio-temporal satellite data.The recent LULC map evidences a drastic changes in urban landscape that resulted in loss of natural drainage and waterbeds causing frequent floods. Digital Elevation Map (DEM) is analysed to know the  low-lying and high elevation topography compared with  Mean Sea Level(MSL)to quantify the impact of flooding during Extreme Rainfall Events(ERE) on the different part of the Bangalore city. Using Triangular Irregular Network (TIN), flood simulation is carried out for highland and lowlandarea  to study immediate affected areas during EREs Storm Water Modelling  is carried out for different regions in the city to obtain flood pattern, time and volume during selected EREs. The framework developed and simulation results are very useful in generation of management and mitigation strategy by various user agencies.</p>

Some lessons to improve adaptation measures in basis to the analysis of three extreme rainfall events and its associated impacts in the Spanish Mediterranean Coast.

2021 ◽  
Author(s):  
Isabel Caballero-Leiva ◽  
Montserrat Llasat-Botija ◽  
María Carmen Llasat
Keyword(s):  
Extreme Rainfall ◽  
Flash Floods ◽  
Mediterranean Coast ◽  
Point Of View ◽  
Adaptation Measures ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Wide Range ◽  
The Mediterranean ◽  
Short Time

<p>The Mediterranean coast of Spain is well known for its pleasant weather, which results in high population densities and large number of tourists. The littoral area is constituted by a rich variety of ecosystems combined with a well-developed industry and agricultural land. The attractive Mediterranean climate has another side of the story, due partially to the Spanish mountain ranges along the east coast. This results in extreme rainfall events that drive flash floods that carry significant economic, environmental and social impact to the affected areas. The mentioned scenario gets more complex when considering the climate change that is already experienced in the Mediterranean region. Among others, the increase in extreme precipitation events envisioned by global climate models. Considering that storms and flash floods are the highest occurrence and most expensive events, it is fair to analyse the adaptation measures in place for the studied area.</p><p>The present work shows the comparative analysis of three recent case studies of major compound hazard events happened in the Mediterranean coast of Spain with special focus on littoral impacts and within a short time frame of 4 months: September 2019, October 2019, and January 2020. The nearness of the events left short time for recovery between them, as well as added aggravation due to the accumulated environmental and economic impacts caused to the region and the Covid-19 pandemics. The work presents a wide range of data (meteorological, hydrological, economical, impact data, etc.), collected from the press and social media as well as from official sources such as CCS, Meteorological agencies, Civil Protection, and others. This allows developing a multidisciplinary approach from the point of view of hydrology, meteorology, sea sciences and social science.</p><p>The analysis of the events is made from a holistic point of view including details as varied as the geographical areas affected up to municipality level, circumstances of casualties, location of extreme hydrometeorological values recorded during the events, environmental impact and economic loss. Furthermore, the different factors driving to each compound hazard event (floods, windstorms, sea surges, ...) and cascade effects have been analysed. Moreover, an analysis of the adaptation measures present at the time is done, along with suggestions of complementary or better adaptation measures for the three cases. Even though the data collection and analysis are made for the entire affected area within the Iberian Peninsula, the impacts and adaptation measures considered in this communication have a focus on the coastal area, including its various littoral ecosystems, coastal infrastructures, tourist sector, etc.</p><p>This work has been done in the framework of the M-CostAdapt (CTM2017-83655-C2-1&2-R) research project, funded by the Spanish Ministry of Science and Innovation (MICINN-AEI/FEDER, UE).</p>

The terraces of Petra, Jordan: archives of a lost agricultural hinterland

2020 ◽  
Author(s):  
Rupert Bäumler ◽  
Bernhard Lucke ◽  
Jago Birk ◽  
Patrick Keilholz ◽  
Christopher O. Hunt ◽  
...  
Keyword(s):  
Irrigation System ◽  
Extreme Rainfall ◽  
Flash Floods ◽  
Available Phosphorus ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Islamic Period ◽  
Extreme Precipitation Events ◽  
Limited Degree ◽  
Agricultural Use

<p>Petra is hidden in rugged arid mountains prone to flash floods, while the dry climate and barren landscape seem hostile to cultivation. Nevertheless, there are countless remains of terraces of so far unknown purpose. We investigated three well-preserved terraces at Jabal Haroun to the south-west of Petra which seemed representative for the diverse geology and types of terraces. A hydrological model shows that the terraces were effective at both control of runoff and collection of water and sediments: they minimized flash floods and allowed for an agricultural use. However, rare extreme rainfall events could only be controlled to a limited degree, and drought years without floods caused crop failures. Pollen and phytoliths in the sediments attest to the past presence of well-watered fields including reservoirs storing collected runoff, which suggest a sophisticated irrigation system. In addition, faeces biomarkers and plant-available phosphorus indicate planned manuring. Ancient land use as documented by the terraces created a green oasis in the desert. They seem to represent Petra's agricultural hinterland, which was lost during the Islamic period due growing aridity and an increased frequency of devastating extreme precipitation events. The heirs of the Nabateans reverted to their original Bedouin subsistence strategies but continue to opportunistically cultivate terrace remains.</p>

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