scholarly journals Disastrous Flash Floods Triggered by Moderate to Minor Rainfall Events. Recent Cases in Coastal Benguela (Angola)

Hydrology ◽  
2021 ◽  
Vol 8 (2) ◽  
pp. 73
Author(s):  
Pedro A. Dinis ◽  
João Huvi ◽  
Marina Cabral Pinto ◽  
Joel Carvalho
Keyword(s):  
Construction Materials ◽  
Flash Floods ◽  
Flood Damage ◽  
Risk Awareness ◽  
Rapid Population Growth ◽  
Regional Survey ◽  
Local Conditions ◽  
Rainfall Events ◽  
Fine Grained ◽  
Quality Construction

The present work focuses on two recent flash floods in coastal Benguela (Angola), both triggered by moderate rainfall but which had disastrous consequences for local populations (namely 71 deaths in 2015 and 17 in 2019). The research involved a regional survey to establish the effects of these floods combined with a geomorphological and socio-economic analysis of the most affected areas to understand the main forcing factors. The two flash floods produced major damage in restricted sectors within very small coastal catchments (<16 km2). The prevalence of fine-grained sedimentary rocks, relatively steep hills, thin soil cover, and vegetation scarcity are natural factors that promote surface runoff. However, socio-economic conditions are most likely the main reasons of flood damage. Namely, rapid population growth with poor planning and making use of low-quality construction materials, the high waste yields that are not properly managed and the absence of flood risk awareness. In the small valleys around the fast-growing cities of coastal Benguela, hazardous flash floods occur recurrently, even after moderate precipitation. Most affected areas are determined by local conditions that compromise drainage at the time of the rainfall event, being very difficult to predict.

scholarly journals Raising risk preparedness by flood risk communication

2015 ◽  
Vol 15 (7) ◽  
pp. 1577-1595 ◽  
Author(s):  
E. Maidl ◽  
M. Buchecker
Keyword(s):  
Risk Communication ◽  
Flood Risk ◽  
Information Needs ◽  
Flood Hazard ◽  
Flood Damage ◽  
Communication Strategy ◽  
Special Focus ◽  
Risk Awareness ◽  
Local Authorities ◽  
Risk Preparedness

Abstract. During the last decade, most European countries have produced hazard maps of natural hazards, but little is known about how to communicate these maps most efficiently to the public. In October 2011, Zurich's local authorities informed owners of buildings located in the urban flood hazard zone about potential flood damage, the probability of flood events and protection measures. The campaign was based on the assumptions that informing citizens increases their risk awareness and that citizens who are aware of risks are more likely to undertake actions to protect themselves and their property. This study is intended as a contribution to better understand the factors that influence flood risk preparedness, with a special focus on the effects of such a one-way risk communication strategy. We conducted a standardized mail survey of 1500 property owners in the hazard zones in Zurich (response rate main survey: 34 %). The questionnaire included items to measure respondents' risk awareness, risk preparedness, flood experience, information-seeking behaviour, knowledge about flood risk, evaluation of the information material, risk acceptance, attachment to the property and trust in local authorities. Data about the type of property and socio-demographic variables were also collected. Multivariate data analysis revealed that the average level of risk awareness and preparedness was low, but the results confirmed that the campaign had a statistically significant effect on the level of preparedness. The main influencing factors on the intention to prepare for a flood were the extent to which respondents evaluated the information material positively as well as their risk awareness. Respondents who had never taken any previous interest in floods were less likely to read the material. For future campaigns, we therefore recommend repeated communication that is tailored to the information needs of the target population.

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 Decision-making on loan services of small and medium enterprises (SMEs) in agrarian areas of North-Eastern Thailand

2020 ◽  
Vol 175 ◽  
pp. 12014
Author(s):  
Pisit Potjanajaruwit
Keyword(s):  
Small And Medium Enterprises ◽  
Statistical Significance ◽  
Construction Materials ◽  
Public Works ◽  
The Other ◽  
Online Questionnaire ◽  
Significance Level ◽  
North Eastern ◽  
Medium Enterprises ◽  
Quality Construction

The purpose of this research was to study the quality and standards of work that influence the operational efficiency of Small and Medium Enterprises in the construction business in Thailand. The data was gathered from 400 construction business entrepreneurs, 342 of which were respondents of an online questionnaire and the other 58 were out of 80 respondents to a questionnaire sent by post. The result revealed that quality and standards of work had effects towards the efficiency of the business. Having been granted permission to do construction from a provincial office of public works was found to affect their benefits and customers’ satisfaction with statistical significance. It was also found that the use of good-quality construction materials and having construction completed on the requested schedule had an effect towards the business’s revenue at the statistical significance level of 0.05.

The Carbonate-Hardening Lime Construction Material Properties Formation during their Long-Term Storage and Use under Normal Conditions

2019 ◽  
Vol 974 ◽  
pp. 187-194 ◽  
Author(s):  
Nikolay V. Lyubomirskiy ◽  
Tamara A. Bakhtina ◽  
Alexander S. Bakhtin ◽  
Sergey I. Fedorkin
Keyword(s):  
Construction Material ◽  
Construction Materials ◽  
Materials Properties ◽  
Long Term Storage ◽  
Efficiency Assessment ◽  
The Stability ◽  
Term Storage ◽  
Long Storage ◽  
Quality Construction

This paper presents the lime binding forced carbonate-hardening materials properties formation study and determins the stability of these properties during long-term storage and use under normal conditions. The tests showed these materials stability properties over time, confirming the strength and density growth of the test samples after long storage due to the calcium hydroxide recrystallization completion into calcium carbonate processes. Also, the results of the samples carbonate hardening study under natural conditions during 18 months are presented. An efficiency assessment of forced carbonate hardening as one of the methods of recycling technogenic CO2 in order to reduce its emissions in the atmosphere, and, in the result, to obtain high-quality construction materials has been made.

Testing of Possible Use of Fine-Grained Alkali Activated Composites in the Construction Industry

2016 ◽  
Vol 865 ◽  
pp. 47-52 ◽  
Author(s):  
Pavel Mec ◽  
Jana Boháčová ◽  
Petr Závrský
Keyword(s):  
Construction Industry ◽  
Setting Time ◽  
Construction Materials ◽  
Inorganic Materials ◽  
Fine Grained ◽  
Granulated Blast Furnace Slag ◽  
Wide Range ◽  
Furnace Slag ◽  
Alkali Activated ◽  
Potential Use

Alkali-activated materials are formed by the alkaline activation of inorganic materials and are characterized by the wide range of potential use. The objective of experiment was to investigate the possibility of use fine-grained alkali activated composites in the construction industry. Selected properties of alkali-activated systems based on granulated blast furnace slag and fine-grained aggregates were determined. At the beginning of the experiment, different samples prepared of 3 types of activators were tested, basic properties (time of workability, initial and final setting time, compressive and flexural strength) and also a possibility of selected retarder use was determined. Then, samples with the best potencial to presumed use were tested in detail and a possibility use as a substitute for selected construction materials were evaluated. On the basis of determined properties, prepared composites could be used as reprofiling mortars, materials for cracks repairing or socle plasters.

scholarly journals ANÁLISE DO ESTADO DE DEGRADAÇÃO DOS TÚNEIS DA ANTIGA CERVEJARIA RITTER, NA CIDADE DE PELOTAS/RS [ Analysis of the state of degradation of tunnels of antique Ritter Beer, in the city of Pelotas/RS ]

2018 ◽  
Vol 14 (2) ◽  
Author(s):  
Lisiê Kremer Cabral ◽  
Andréia Schneid ◽  
José Henrique Carlúcio Cordeiro ◽  
Ariela da Silva Torres
Keyword(s):  
Built Environment ◽  
Water Supply ◽  
Construction Materials ◽  
The State ◽  
Historical Buildings ◽  
Rs Analysis ◽  
The City ◽  
Quality Construction

RESUMO: Patologia, termo oriundo da medicina, é a ciência que estuda as anomalias de um determinado corpo. Na construção civil é utilizada por extensão para analisar e identificar os problemas e defeitos de uma edificação. Alguns aspectos favorecem o aparecimento dessas anomalias, como a utilização de materiais de construção de baixa qualidade, mão de obra desqualificada e ausência de responsável técnico pela construção. Nas edificações históricas, o estudo das manifestações patológicas se torna mais complexo devido às restrições na intervenção do prédio. A importância da preservação do ambiente construído é evidente para conservação da história na formação e identidade da cidade. O presente trabalho apresenta o levantamento de dados e análise das manifestações patológicas em um túnel da antiga cervejaria Ritter, edificação de 117 anos, localizado na cidade de Pelotas/RS. Assim, com base na metodologia de Lichtenstein, foi realizado o levantamento de dados com mapeamento, o diagnóstico das patologias e, por fim, apontadas as possíveis soluções para cada anomalia encontrada. As manifestações mais relevantes são manchas de umidade, sujidade, mofo, apontando que a maioria das manifestações patológicas encontradas se devem à presença indevida de água na edificação, em que a principal solução é a drenagem do terreno e secagem da fonte de alimentação de água. Este estudo apresentou resultados satisfatórios e poderá auxiliar outros trabalhos relacionados a manifestações patológicas em edificações.ABSTRACT: Pathology, a term derived from medicine, is the science that studies the anomalies of a particular body. In civil construction is used by extension to analyze and identify the problems and defects of a building. Some aspects favor the emergence of these anomalies, such as the use of low quality construction materials, disqualified manpower and lack of technical responsibility for construction. In the historical buildings, the study of pathological manifestations becomes more complex because of the restrictions in the intervention of the building. The importance of preservation of the built environment is evident for the conservation of history in the formation and identity of the city. This paper presents the survey of data and analysis of the pathological manifestations in a tunnel of the old Ritter Brewery, building of 117 years, located in the city of Pelotas/RS. Based on the methodology of Lichtenstein, it was carried out the survey of data with mapping, the diagnosis of the pathologies and finally possible solutions for each anomaly found. The most relevant manifestations are stains of moisture, dirt, mold, indicating that most of the pathological manifestations are due to the undue presence of water in the building, where the main solution is the drainage of the soil and drying of the source of water supply. This study presented satisfactory results and may support other papers related to pathological manifestations in buildings.

scholarly journals Meteorological analysis of flash floods in Artvin (NE Turkey) on August 24, 2015

2017 ◽  
Author(s):  
Hakki Baltaci
Keyword(s):  
Black Sea ◽  
Flash Floods ◽  
Flood Damage ◽  
Slope Instability ◽  
Economic Losses ◽  
The Black Sea ◽  
Black Sea Coast ◽  
Accumulated Rainfall ◽  
Convective Cells ◽  
Meteorological Analysis

Abstract. On August 24, 2015 intense rainfall episodes generated flash floods and landslides on the eastern Black Sea coast of Turkey. As a consequence of the heavy rainstorm activity over Artvin and its surroundings (NE Turkey), 11 people died and economic losses totaled a million dollars. During the six hours of the event (from 05:00 UTC to 11:00 UTC), total accumulated rainfall of 136, 64, and 109 mm was measured in the Hopa, Arhavi, and Borçka settlements of Artvin city, respectively. This study comprehensively investigates the meteorological characteristics of those flash floods. In terms of synoptic mechanisms, the cut-off surface low from the summer Asian monsoon settled over the eastern Black Sea. After two days of quasi-stationary conditions of this cyclone, sea surface temperatures (SSTs) reached 27.5 °C (1.5 °C higher than normal) and low-level moisture convergence developed. In addition, transfer of moisture by warm northerly flows from the Black Sea and relatively cool southerly flows from the land coasts of the Artvin district exacerbated the unstable conditions, and thus, played a significant role in the development of deep convective cells. Severe rainstorms as well as the slope instability of the region triggered landslides and worsened flood damage in the Artvin.

scholarly journals Characterization of Historic Binders and Stones of a Ruined Medieval Church (Hungary)

2020 ◽  
Author(s):  
Zsuzsanna Kósa ◽  
Ákos Török
Keyword(s):  
Moisture Content ◽  
Construction Materials ◽  
Selective Dissolution ◽  
Test Methods ◽  
Schmidt Hammer ◽  
Fine Grained ◽  
Medieval Church ◽  
History Of ◽  
Non Destructive

Construction materials of a partly ruined Medieval church of Central Hungary were studied in details to assess its conditions and to obtain information on the phases of construction. At first, digital images were taken to create a 3D model of the remaining walls. The material properties were measured in situ using non-destructive test methods. Strength parameters of stone and render were assessed by Schmidt hammer, while moisture content was measured by a portable moisture meter. According to lithological descriptions and thin-section analyses limestone prevail in the monument. The most common Miocene limestone is represented by various lithologies, such as cemented macro porous limestone, fine-grained porous limestone, oolitic limestone and bioclastic limestone. Mesozoic micritic well cemented limestone and Tertiary limonitic sandstone were also identified at the ruins. The most common weathering forms are selective dissolution, multiple flaking and biological colonisation. Renders used in the structure represents the long history of the structure from Medieval lime-based mortars to Portland cement containing latest applications. The former one is composed of quartz send in lime binder. According to Schmidt hammer tests, the rebound values of the replacement stone is higher than that of the original porous limestone. There is a distinct difference in the moisture content of the stone and render. Orientation/exposure of the wall also influences the moisture content. The gathered information allows for designing better repair methods and helps in the planning of the maintenance of the medieval stone heritage.

scholarly journals THE APPLICABILITY OF DISINTEGRATION TESTS FOR COHESIVE ORGANIC SOILS

2015 ◽  
Vol 23 (1) ◽  
pp. 1-14 ◽  
Author(s):  
Anne-Katrin GROßE ◽  
Stefan CANTRÉ ◽  
Fokke SAATHOFF
Keyword(s):  
Boundary Conditions ◽  
Large Scale ◽  
Erosion Resistance ◽  
Construction Materials ◽  
Aggregate Stability ◽  
Organic Soils ◽  
Fine Grained ◽  
Evaluation Procedures ◽  
Dredged Materials ◽  
Top Soil

The use of ripened fine-grained organic dredged materials as construction materials, e.g. as top soil on slopes such as landfills or dikes, is an important contribution to environmental engineering science. The materials are legally considered a waste and need to be beneficially re-used. Therefore, not only standard geotechnical parameter shave to be determined but also their erosion resistance which is a particularly critical environmental parameter. There is a variety of different tests to determine the flow dependent erosion resistance of soils, such as the erosion function apparatus (Briaud et al. 2001). In this study, however, the focus lays on the aggregate stability as an indicator for the erosion resistance under static loading, which can be determined using wet sieving and disintegration tests. The disintegration tests after Weißmann (2003) and Endell (RPW 2006) have a similar setup; however, the specific boundary conditions for the tests as well as the evaluation procedures are different. Weißmann proposed his test to determine the erosion stability of dike cover materials while the Endell test should be used for mineral sealing liners in navigation channels. In this study both tests have been used to evaluate the aggregate stability of fine-grained organic dredged materials that have been installed in large-scale research dike facilities and in the recultivation layers of different landfills. The materials showed good visual performance with respect to rainfall induced erosion so far; however, problems in determining erosion and aggregate stability indices limit the value of the studies: both disintegration tests investigated have major limitations with respect to the organic soils tested. Particularly the evaluation methods are not suitable for the soils but also some boundary conditions are critical and are discussed in this paper. The gained knowledge is a valuable basis for the development of standard characterisation methods for dredged materials in environmental and geotechnical applications.

From Flash Flood Vulnerability and Risk Assessment to Property Damage Prediction: the Value of Machine Learning

2020 ◽  
Author(s):  
Atieh Alipour ◽  
Peyman Abbaszadeh ◽  
Ali Ahmadalipour ◽  
Hamid Moradkhani
Keyword(s):  
Machine Learning ◽  
Flash Flood ◽  
Rapid Onset ◽  
Flash Floods ◽  
Flood Damage ◽  
Flood Events ◽  
Property Damage ◽  
Damage Prediction ◽  
Financial Consequences

&lt;p&gt;Flash floods, as a result of frequent torrential rainfalls caused by tropical storms, thunderstorms,&lt;br&gt;and hurricanes, are a prevalent natural disaster in the southeast U.S. (SEUS), which frequently&lt;br&gt;threaten human lives and properties in the region. According to the U.S. National Weather&lt;br&gt;Service (NWS), flash floods generally initiate within less than six hours of an intense rainfall&lt;br&gt;onset. Therefore, there is a limited chance for effective and timely decision-making. Due to the&lt;br&gt;rapid onset of flash floods, they are costly events, such that only during 1996 to 2017 flash&lt;br&gt;floods imposed 7.5 billion dollars property damage to the SEUS. Therefore, estimating the&lt;br&gt;potential economic damages as a result of flash floods are crucial for flood risk management and&lt;br&gt;financial appraisals for decision makers. A multitude of studies have focused on flood damage&lt;br&gt;modeling, few of which investigated the issue on a large domain. Here, we propose a systematic&lt;br&gt;framework that considers a variety of factors that explain different risk components (i.e., hazard,&lt;br&gt;vulnerability, and exposure) and leverages Machine Learning (ML) for flood damage prediction.&lt;br&gt;Over 14,000 flash flood events during 1996 to 2017 were assessed to analyze their characteristics&lt;br&gt;including frequency, duration, and intensity. Also, different data sources were utilized to derive&lt;br&gt;information related to each event. The most influential features are then selected using a multi&lt;br&gt;criteria variable selection approach. Then, the ML model is implemented for not only binary&lt;br&gt;classification of damage (i.e., whether a flash flood event caused any damage or not), but also for&lt;br&gt;developing a model to predict the financial consequences associated with flash flood events. The&lt;br&gt;results indicate a high accuracy for the classifier, significant correlation and relatively low bias&lt;br&gt;between the predicted and observed property damages showing the effectiveness of proposed&lt;br&gt;methodology for flash flood damage modeling applicable to variety of flood prone regions.&lt;/p&gt;

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