scholarly journals Hydrometeorological Conditions Leading to the 2015 Salgar Flash Flood: Lessons for Vulnerable Regions in Tropical Complex Terrain

2019 ◽  
Author(s):  
Carlos D. Hoyos ◽  
Lina I. Ceballos ◽  
Jhayron S. Pérez ◽  
Julián Sepúlveda ◽  
Silvana M. López ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Latin American ◽  
Complex Terrain ◽  
Flash Flood ◽  
Flash Floods ◽  
Precipitation Event ◽  
Orographic Rainfall ◽  
Short Period ◽  
Local Risk

Abstract. Flash floods are a recurrent hazard for many developing Latin American regions due to their complex mountainous terrain and the rainfall characteristics in the Tropics. These regions often lack the timely and high-quality information needed to assess, in real-time, the threats to the vulnerable communities due to extreme hydrometeorological events. The systematic assessment of past extreme events allows improving our prediction capabilities of flash floods. In May 2015, a flash flood in La Liboriana basin, municipality of Salgar, Colombia, caused more than 100 casualties and significant infrastructure damage. Despite the data scarcity, the climatological aspects, meteorological conditions, and first-order hydrometeorological mechanisms associated with La Liboriana flash flood, including orographic intensification and the spatial distribution of the rainfall intensity relative to the basin's geomorphological features, are studied using precipitation information obtained using a weather radar quantitative precipitation estimation (QPE) technique, as well as from satellite products, in situ rain gauges from neighboring basins, quantitative precipitation forecasts (QPFs) from an operational Weather Research and Forecasting (WRF) model application, and data from reanalysis products. La Liboriana flash flood took place during a period with negative precipitation anomalies over most of the country as a result of an El Niño event. However, during May 2015, moist easterly flow towards the upper part of La Liboriana caused significant orographic rainfall enhancement. The overall evidence shows an important role of successive precipitation events in a relatively short period, and of orography, in the spatial distribution of rainfall and its intensification as convective cores approached the steepest topography. There were three consecutive events generating significant rainfall within La Liboriana basin, and no single precipitation event was exceptionally large to generate the flash flood, but rather the combined role of precedent rainfall, and extreme hourly precipitation triggered the event. The results point to key lessons for improving local risk reduction strategies in vulnerable regions with complex terrain.

scholarly journals Meteorological conditions leading to the 2015 Salgar flash flood: lessons for vulnerable regions in tropical complex terrain

2019 ◽  
Vol 19 (11) ◽  
pp. 2635-2665 ◽  
Author(s):  
Carlos D. Hoyos ◽  
Lina I. Ceballos ◽  
Jhayron S. Pérez-Carrasquilla ◽  
Julián Sepúlveda ◽  
Silvana M. López-Zapata ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Latin American ◽  
Complex Terrain ◽  
Flash Flood ◽  
Flash Floods ◽  
Meteorological Conditions ◽  
Precipitation Event ◽  
Short Period ◽  
Local Risk

Abstract. Flash floods are a recurrent hazard for many developing Latin American regions due to their complex mountainous terrain and the rainfall characteristics in the tropics. These regions often lack the timely and high-quality information needed to assess, in real time, the threats to the vulnerable communities due to extreme hydrometeorological events. The systematic assessment of past extreme events allows us to improve our prediction capabilities of flash floods. In May 2015, a flash flood in the La Liboriana basin, municipality of Salgar, Colombia, caused more than 100 casualties and significant infrastructure damage. Despite the data scarcity, the climatological aspects, meteorological conditions, and first-order hydrometeorological mechanisms associated with the La Liboriana flash flood, including orographic intensification and the spatial distribution of the rainfall intensity relative to the basin's geomorphological features, are studied using precipitation information obtained using a weather radar quantitative precipitation estimation (QPE) technique, as well as from satellite products, in situ rain gauges from neighboring basins, quantitative precipitation forecasts (QPFs) from an operational Weather Research and Forecasting Model (WRF) application, and data from reanalysis products. The La Liboriana flash flood took place during a period with negative precipitation anomalies over most of the country as a result of an El Niño event. However, during May 2015, moist easterly flow towards the upper part of La Liboriana caused significant orographic rainfall enhancement. The overall evidence shows an important role of successive precipitation events in a relatively short period and of orography in the spatial distribution of rainfall and its intensification as convective cores approached the steepest topography. There were three consecutive events generating significant rainfall within the La Liboriana basin, and no single precipitation event was exceptionally large enough to generate the flash flood, but rather the combined role of precedent rainfall and the extreme hourly precipitation triggered the event. The results point to key lessons for improving local risk reduction strategies in vulnerable regions with complex terrain.

Surface Water Management and Modelling in the Sakia El Hamra Hydraulic Basin (Southern Morocco)

2020 ◽  
Author(s):  
Nafia El-alaouy ◽  
Aicha Moumni ◽  
Badr-eddine Sebbar ◽  
Abdeljalil Gouzrou ◽  
Aberrahman Lahrouni
Keyword(s):  
Flash Flood ◽  
Hydrological Regime ◽  
Shape Index ◽  
Flash Floods ◽  
Drainage Density ◽  
Agricultural Lands ◽  
Surface Water Management ◽  
Short Period ◽  
Long Time ◽  
Log Normal

<p>Due to its arid to semi-arid climate, Morocco often faces significant intense rainfall periods that can generate flash floods and raging torrents causing serious damage in a very short period of time. In this context, these recent years, the watershed corresponding to the SAKIA EL HAMRA wadi has known devastating downpours and excessive heavy rains that caused severe floods in Laayoune city and its regions.</p><p>The watershed of Sakia El Hamra covers an area of 82000 km<sup>2</sup>, that drains to Sakia El Hamra wadi, a stream of about 447 km long, crosses the basin in its northern part in the East-to-West direction, to discharge into the Atlantic Ocean at the outlet called Foum El Oued. This zone often experiences dangerous torrents of water and violent flash floods, specifically in the northern part of Laayoune city. For example, a flash flood has occurred at the end of October 2016. The peak flow was far in excess of the average (3000 m<sup>3</sup>/s against 410m<sup>3</sup>/s). This river flood, lasted for about 10 h, caused damage to the infrastructure and destruction of agricultural lands near Foum El Oued.</p><p>The objective of this study is to investigate, through modelling, the hydrological regime of SAKIA EL HAMRA watershed to prevent the floods in the future and improve warning systems. The hydrological parameters of the watershed were determined by WMS software, namely: zone extent, perimeter, slope, basin’s average elevation, Gravelius compactness index, Horton shape index, average altitude, drainage density and concentration time.</p><p>Flood flow return was simulated using the Log-normal distribution, using a long time-series of flow and maximum daily and annual precipitation data, recorded between 1985 and 2016, at the Airport station in Laayoune city. The results showed that during flash floods with known flows, water level can reach up to 13 meters, with high flow velocities flooding hundreds of hectares of surrounding plains at the northern part of the city of Laayoune and agricultural lands near Foum El Oued.</p>

scholarly journals Assessing long term flash flooding frequency using historical information

2016 ◽  
Vol 48 (1) ◽  
pp. 1-16 ◽  
Author(s):  
David R. Archer ◽  
Geoff Parkin ◽  
Hayley J. Fowler
Keyword(s):  
Time Series ◽  
Flash Flood ◽  
Climatic Variability ◽  
Flash Floods ◽  
Abrupt Onset ◽  
Flood Frequency ◽  
Historical Information ◽  
Short Period ◽  
Historical Series ◽  
Historical Accounts

Flash floods are distinguished from ‘normal flooding’ by an abrupt onset arising from intense short period rainfall. Historical information based on pre-gauged descriptive information is used to prepare time series of flash floods for Northeast England and Southwest England as decadal numbers of events from 1800. The time series show a minimum in the late twentieth century for both locations. Flash flood frequency is then assessed for three locations in Northeast England by comparing recent extreme floods with historical accounts: (1) an urban pluvial flood in Newcastle in June 2012, (2) a severe flood in September 1968 on the Cotting Burn, a small ungauged tributary of the River Wansbeck, and (3) an extreme rate of rise in river level on the River Wansbeck in August 1994. Although there have been no comparable recent occurrences, several flash floods of equal or greater magnitude at the same locations were identified from historical accounts. Using the longer historical record in conjunction with limited recent observations has advantages when assessing the frequency of occurrence of rare events. However, these advantages are tempered by the possibility of non-stationarity in the historical series owing to catchment changes, from natural climatic variability and from potential anthropogenic climate change.

scholarly journals Simulating Flash Floods Using Geostationary Satellite-Based Rainfall Estimation Coupled with a Land Surface Model

Hydrology ◽  
2020 ◽  
Vol 7 (1) ◽  
pp. 9 ◽  
Author(s):  
Dwi Prabowo Yuga Suseno ◽  
Tomohito J. Yamada
Keyword(s):  
Spatial Distribution ◽  
River Basin ◽  
Land Surface ◽  
River Flow ◽  
Flash Flood ◽  
Land Surface Model ◽  
Flash Floods ◽  
Flood Mitigation ◽  
Surface Model ◽  
Flow Simulations

Clarifying hydrologic behavior, especially behavior related to extreme events such as flash floods, is vital for flood mitigation and management. However, discharge and rainfall measurement data are scarce, which is a major obstacle to flood mitigation. This study: (i) simulated flash floods on a regional scale using three types of rainfall forcing implemented in a land surface model; and (ii) evaluated and compared simulated flash floods with the observed discharge. The three types of rainfall forcing were those observed by the Automated Meteorological Data Acquisition System (AMeDAS) (Simulation I), the observed rainfall from the Ministry of Land, Infrastructure and Transportation (MLIT) (Simulation II), and the estimated rainfall from the Multi-purpose Transport Satellite (MTSAT), which was downscaled by AMeDAS rainfall (Simulation III). MLIT rainfall observations have a denser station network over the Ishikari River basin (spacing of approximately 10 km) compared with AMeDAS (spacing of approximately 20 km), so they are expected to capture the rainfall spatial distribution more accurately. A land surface model, the Minimal Advance Treatments of Surface Interaction and Runoff (MATSIRO), was implemented for the flash flood simulation. The river flow simulations were run over the Ishikari river basin at a 1-km grid resolution and a 1-h temporal resolution during August 2010. The statistical performance of the river flow simulations during a flash flood event on 23 and 24 August 2010 demonstrated that Simulation I was reasonable compared with Simulation III. The findings also suggest that the advantages of the MTSAT-based estimated rainfall (i.e., good spatial distribution) can be coupled with the benefit of direct AMeDAS observations (i.e., representation of the true rainfall).

scholarly journals Using High-Resolution Satellite Rainfall Products to Simulate a Major Flash Flood Event in Northern Italy

2013 ◽  
Vol 14 (1) ◽  
pp. 171-185 ◽  
Author(s):  
Efthymios I. Nikolopoulos ◽  
Emmanouil N. Anagnostou ◽  
Marco Borga
Keyword(s):  
High Resolution ◽  
Complex Terrain ◽  
Flash Flood ◽  
Flash Floods ◽  
Hydrologic Model ◽  
Flood Event ◽  
Medium Size ◽  
Soil Conditions ◽  
Model Parameters ◽  
Satellite Rainfall

Abstract Effective flash flood warning procedures are usually hampered by observational limitations of precipitation over mountainous basins where flash floods occur. Satellite rainfall estimates are available over complex terrain regions, offering a potentially viable solution to the observational coverage problem. However, satellite estimates of heavy rainfall rates are associated with significant biases and random errors that nonlinearly propagate in hydrologic modeling, imposing severe limitations on the use of these products in flood forecasting. In this study, the use of three quasi-global and near-real-time high-resolution satellite rainfall products for simulating flash floods over complex terrain basins are investigated. The study uses a major flash flood event that occurred during 29 August 2003 on a medium size mountainous basin (623 km2) in the eastern Italian Alps. Comparison of satellite rainfall with rainfall derived from gauge-calibrated weather radar estimates showed that although satellite products suffer from large biases they could represent the temporal variability of basin-averaged precipitation. Propagation of satellite rainfall through a distributed hydrologic model revealed that systematic error in rainfall was severely magnified when transformed to error in runoff under dry initial soil conditions. Simulation hydrographs became meaningful only after recalibrating the model for each satellite rainfall input separately. However, the unrealistic values of model parameters after recalibration show that this approach is erroneous and that model recalibration using satellite rainfall data should be treated with care. Overall, this study highlights the need for improvement of satellite rainfall retrieval algorithms in order to allow a more appropriate use of satellite rainfall products for flash flood applications.

scholarly journals Measuring Vulnerability to Flash Flood of Urban Dwellers

2021 ◽  
pp. 317-354
Author(s):  
Md. Enamul Huq ◽  
Zhenfeng Shao ◽  
Ahmed Abdullah Al Dughairi ◽  
Md. Nazirul Islam Sarker ◽  
Cai Bowen ◽  
...  
Keyword(s):  
Climatic Condition ◽  
Flash Flood ◽  
Geographic Location ◽  
Flash Floods ◽  
Primary Data ◽  
Five Factors ◽  
Short Period ◽  
Real Picture ◽  
Insight Into ◽  
Slum Population

AbstractFlash floods are unexpected, localized flood events that occur when an exceptional amount of rain falls happens over a short period of time. In South Asia, it is mostly disastrous, for example, in 2017 flash floods killed approximately 1200 people from India, Nepal, and Bangladesh. However, it is also common in Dhaka megacity, Bangladesh due to its geographic location, monsoon climatic condition and surrounding rivers. Though it is impossible to avoid them, the losses and damages of hazards can be reduced effectively by using appropriate techniques. This study aims to determine the responsible factors and measure the household vulnerability to flash flood as a tool of mitigation. The study has been conducted based on primary data. Therefore, data were collected from both slum and non-slum population to cover the entire urban habitats. Data were collected with a structured questionnaire based on five factors (social, economic, institutional, structural, and environmental) of vulnerability to flash flood. The key feature of this paper is to provide an insight into real picture of vulnerability to flash flood for urban habitants. Moreover, this practical approach is useful to quantify hazard-induced vulnerabilities not only for Dhaka megacity but also for other cities of the globe.

scholarly journals Translation, Re-translation, and the Reception of Arabic Literature in English: The Case of Ahlam Mostaghenami’s Novel Chaos of the Senses

2021 ◽  
Vol 11 (5) ◽  
pp. 230
Author(s):  
Musa Alzghoul ◽  
Tahani Alazzam
Keyword(s):  
Latin American ◽  
West Germany ◽  
Arabic Literature ◽  
Reception Theory ◽  
American Novels ◽  
Short Period ◽  
English Speaking ◽  
The Senses

The current study compares the two translations of Ahlam Mostaghenami’s second novel Fawda Al-Hawas into English as Chaos of the Senses by (Baria Ahmar Sreih, 2004) and Chaos of the Senses by (Nancy Roberts, 2015) and examines the reception of both translations in the English-speaking communities where they were circulated. The study seeks to find out answers to questions about: the reasons for retranslating Fawda Al-Hawas after a relatively short period of time after its first translation, the roles of human agents such as the author, translators, and publishers in the production and reception of the two translations of Fawda Al-Hawas  , how the retranslation tried to avoid previous problems, if any, that hindered the circulation of the first translation, the role of paratexts in the reception of the two translations. The study draws on major concepts form reception theory as adopted by (Brown, 1994) in her study of Latin American novels published in West Germany. Specifically, the current study draws a close comparison of the paratexts associated with the two translations of Mostaghenami’s Fawda Al-Hawasas well as the roles of stakeholders. The study concludes that despite the use of more paratextual elements as well as textual improvements in the retranslation, it has not shown better results in terms of reception and circulation.   Received: 4 May 2021 / Accepted: 9 August 2021 / Published: 5 September 2021

Numerical investigation of sediment-charged flash flood due to a cascade of natural dam failures

2020 ◽  
Author(s):  
Mingfu Guan
Keyword(s):  
Flash Flood ◽  
Landslide Dam ◽  
Flash Floods ◽  
Steep Slope ◽  
River Valley ◽  
Dam Failure ◽  
Dam Failures ◽  
Short Period ◽  
Natural Dam ◽  
High Sediment

<p>Landslide natural dams are commonly formed in a river valley of mountainous areas due to heavy rainfall or earthquake, which can be a complete or partial blockage. Different from conventional man-made dams, natural dams typically comprise unconsolidated and poorly sorted material, and are vulnerable to failure and breaching in short period due to overtopping or seepage. For those small sediment blockage in a river valley, their failures frequently occur during high intense rainfalls, which will induce a large flash flood with high-concentrated sediment downstream in a short period, and the magnitude is likely to be amplified along the flow direction due to the inclusion of a large amount of sediment. This can result in significant and sudden debris flow or high sediment-charged flash flood in the downstream for human life and property. Cascade failures of a series of natural dams in a gully have been considered to be a primary reason for the enlargement of high sediment-laden flash flood. In general, cascading natural dams can be formed along the sloping channel due to the randomness and unpredictability of landslides, which complexes the hydraulics of landslide dam failures.</p><p>This study evaluates the formation and development of sediment-charged flash floods due to cascading failure of natural dams through detailed hydro-morphodynamic modelling. The model used is based on shallow water theory and it has been successful in predicting the flow and morphological process during sudden dam-break, as well as full and partial dyke-breach.  The study first calibrates the model with experiemntal data of a cascade of partical blockage dam failures. Then the calibrated model is applied to two types of natural dam failure cases: (1) straight steep slope channel with a series of small partial blockage dams; (2) bend channel with steep slope including a series of partical blockage dams. For both cases, various scenarios are modelled, including: (1) failure of a single dam in a sloping channel, (2) failure of two dams in a sloping channel, (3) failure of multiple landslide dams (four) in a sloping channel. Based on the detailed model results, the study systematically explores the tempo-spatial evolution of sediment-charged flash floods (discharge, flow velocity, and flow concentration) and geomorphic properties along the steep sloping channel.  The effects of in-channel erosion and flow-driven sediment from dams on the evolution of flood dynamic process are analysed.  The results improve the understanding of the formation and development mechanism of flash floods due to cascading landslide dam failures.  The findings are beneficial for downstream flood risk assessment and developing control strategies for landslide-induced floods.</p>

Coronary Intervention with the Excimer Laser: Review of the Technology and Outcome Data

2016 ◽  
Vol 11 (1) ◽  
pp. 27
Author(s):  
John Rawlins ◽  
◽  
◽  
◽  
◽  
...  
Keyword(s):  
Excimer Laser ◽  
Coronary Intervention ◽  
Outcome Data ◽  
Boston Scientific ◽  
Technical Aspects ◽  
Safety And Efficacy ◽  
Percutaneous Coronary ◽  
Short Period ◽  
Complex Lesions

Excimer laser coronary atherectomy (ELCA) is a long-established adjunctive therapy that can be applied during percutaneous coronary intervention (PCI). Technical aspects have evolved and there is an established safety and efficacy record across a number of clinical indications in contemporary interventional practice where complex lesions are routinely encountered. The role of ELCA during PCI for thrombus, non-crossable or non-expandable lesions, chronic occlusions and stent under-expansion are discussed in this review. The key advantage of ELCA over alternative atherectomy interventions is delivery on a standard 0.014-inch guidewire. Additionally, the technique can be mastered by any operator after a short period of training. The major limitation is presence of heavy calcification although when rotational atherectomy (RA) is required but cannot be applied due to inability to deliver the dedicated RotaWire™ (Boston Scientific), ELCA can create an upstream channel to permit RotaWire passage and complete the case with RA – the RASER technique.

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