Impact Of Flash Floods Research Articles

A literature review: rainfall thresholds as flash flood monitoring for an early warning system

ABSTRACT Flash floods, increasingly common and impactful, can be better managed through effective early warning systems. This study reviews methods for determining rainfall thresholds using empirical, hydrological, and machine learning approaches. Empirical methods, based on historical data, identify patterns between rainfall and floods but struggle with spatial and temporal variations. Hydrological methods, which consider watershed characteristics, offer greater accuracy but require detailed data. Machine learning, with its capacity for real-time, adaptive analysis of big data, shows promise for improving predictions. Integrating these approaches can enhance early warning systems, making them more effective in the face of climate change and significantly reducing the impact of flash floods.

Assessing the Impact and Coping Measures of Urban Flash Floods in Quetta during Monsoon 2022

The research study was carried out to assess the impact and coping measures of flash floods in Quetta City during Monsoon 2022. A combination of both qualitative and quantitative research method was used as part of “After-Only” research design. Primary data sources included survey of the affected areas in Quetta City and interviews of officials from various departments. Secondary data sources involved records from relevant departments, newspapers, journals and internet. Random sampling technique was adopted during the survey and thematic analysis of total sample size of 390 was carried out. .The findings have revealed that unchecked urbanization and construction in waterways amplified the damaged caused by flash floods in Quetta in 2022. The empirical evidences and survey conducted of affected areas pointed out lack of implementation of available regulatory measures. In order to mitigate the effect of any future flash flood, existing regulatory mechanism in required to be implemented in true letter and spirit which should include reclaiming of encroached waterways, planning for rehabilitation of affected households to suitable location and detailed urban planning to cater for expansion of Quetta City.

The Interconnection between Climate Cycles and Geohazards in Urban Areas of the Tourist Island of Mallorca, Spain

The island of Mallorca has experienced major interventions and transformations of the territory, with unprecedented urban development related to growing tourism activity. In this paper, we present a spatio-temporal analysis—by using spectral analysis techniques—of climate cycles on the island of Mallorca (Spain) and their correlation with the occurrences of landslides and flash floods. Both geohazards are closely related to wet periods, which are controlled by different, well-known natural cycles: ENSO, the NAO, sunspot, etc. Geostatistical methods are used to map the distribution of rainfall, as well as a spatial representation of the spectral confidence of the different natural cycles, to define the hazardous areas on the island. The cycles with the greatest influence on rainfall in Mallorca are El Niño–Southern Oscillation (ENSO) (5.6 y and 3.5 y), the North Atlantic Oscillation (NAO) (7.5 y), and Quasi-Biennial Oscillation (QBO). Recorded events of both rockfalls and flash floods exhibit a strong correlation with the climate indices of QBO, ENSO, the NAO, and sunspot activity. This correlation is particularly pronounced with QBO, as this cycle has a higher frequency than the others, and QBO is observed as part of the other cycles in the form of increases and decreases during periods of higher ENSO, NAO, and sunspot values. However, the impact of flash floods is also significant in the southeast part of the island, despite its lower levels of rainfall. The most dangerous episodes are related to ENSO (6.4 y) and the NAO. The validation of the methodology employed is strengthened by incorporating information from the flash flood data, as it offers comprehensive coverage of the entire island, compared to the landslide database, which is confined to the Serra de Tramuntana region. The study reveals that the city of Palma and the municipality of Calvià, as well as the central and eastern urban areas of the island, are the most vulnerable regions to intense rainfall and its consequences.

Understanding flash flooding in the Himalayan Region: a case study

The Himalayan region, characterized by its substantial topographical scale and elevation, exhibits vulnerability to flash floods and landslides induced by natural and anthropogenic influences. The study focuses on the Himalayan region, emphasizing the pivotal role of geographical and atmospheric parameters in flash flood occurrences. Specifically, the investigation delves into the intricate interactions between atmospheric and surface parameters to elucidate their collective contribution to flash flooding within the Nainital region of Uttarakhand in the Himalayan terrain. Pre-flood parameters, including total aerosol optical depth, cloud cover thickness, and total precipitable water vapor, were systematically analyzed, revealing a noteworthy correlation with flash flooding event transpiring on October 17th, 18th, and 19th, 2021. Which resulted in a huge loss of life and property in the study area. Contrasting the October 2021 heavy rainfall with the time series data (2000–2021), the historical pattern indicates flash flooding predominantly during June to September. The rare occurrence of October flash flooding suggests a potential shift in the area's precipitation pattern, possibly influenced by climate change. Robust statistical analyses, specifically employing non-parametric tests including the Autocorrelation function (ACF), Mann–Kendall (MK) test, Modified Mann–Kendall, and Sen's slope (q) estimator, were applied to discern extreme precipitation characteristics from 2000 to 201. The findings revealed a general non-significant increasing trend, except for July, which exhibited a non-significant decreasing trend. Moreover, the results elucidate the application of Meteosat-8 data and remote sensing applications to analyze flash flood dynamics. Furthermore, the research extensively explores the substantial roles played by pre and post-atmospheric parameters with geographic parameters in heavy rainfall events that resulted flash flooding, presenting a comprehensive discussion. The findings describe the role of real time remote sensing and satellite and underscore the need for comprehensive approaches to tackle flash flooding, including mitigation. The study also highlights the significance of monitoring weather patterns and rainfall trends to improve disaster preparedness and minimize the impact of flash floods in the Himalayan region.

Climate Changes and Distribution of Water Borne Diseases in Eastern, Afghanistan

Subject to a high burden of diarrheal disease, the east provinces of Afghansitan are also suceptable to climate changes. The most devastating consequences are the occurrence of flash floods and aridity. The climate changes trends will exacerbate the health risks associated with deficiencies in water, sanitation and hygiene. This study investigated the distribution of diarrheal disease in the east provinces and how linked with climate variables. Using monthly aggregated new cases of acute diarrhea reported between 2018 and 2023 by Health Management information system department, Ministry of public health of Afghanistan. We found seasonal variation and temperature are positively linked with diarrhea incidence. Initial analysis shows a seasonal trend in diarrhea cases, with peak incidence occurring in summer and reduced incidence during winter months. The recorded diarrhea cases show marked increment in the incidence of acute watery diarrhea in 2023 in eastern region. the incidence of diarrhea cases increased in 2023 (480/1000 population at risk) compared to 2019 (360/1000 population at risk) in eastern region. The impact of flash floods and Aridity as a consequences of climate change in Afghanistan cannot be underestimated. Increasing the incidence of water borne diseases like diarrhea and other infectious diseases outbreaks are important issues that could be assessed. Allowing for policymakers to account for potential impacts of climate change in their public health assessments, and provides a framework that could be extended to similar settings.

Modelling spatiotemporal impact of flash floods on power distribution system and dynamic service restoration with renewable generators considering interdependent critical loads

AbstractIn recent decades, flash floods have become more common because of climate change and are considered a substantial risk for many cities worldwide. This catastrophic natural hazard presents a significant threat to critical infrastructure in urban areas, particularly the power distribution system. As modern societies are much more dependent on electrical energy these days, it is essential and imperative to make existing distribution systems resilient against flash flooding. Although researchers in this area have proposed various algorithms to impart resilience to a distribution system, however, the focus in these works is on wind‐related events such as hurricanes, cyclones, and windstorms. Therefore, here, the spatiotemporal effects of a flash flood on the distribution system are modelled using a grid‐based hydrodynamic model. The evolving line faults are then included in the proposed resilience‐oriented time horizon‐based service restoration model that also considers dynamic load demand, heavy uncertainties related to renewable generation, and interdependence among critical loads. Finally, the resilience of the distribution system's response is assessed using an operational resilience metric. The efficacy of the proposed framework is evaluated on IEEE 33‐bus and 69‐bus systems and the results show that the model provides an efficient restoration solution despite increased complexity caused by varying conditions.

Влияние ливневых паводков на строительство сооружений по сбору дождевой воды

Introduction. The lack of fresh water has become a serious problem. The main causes of the water crisis are population growth and climate change. Egypt is a very arid country which is facing water scarcity due to increasing demand and limited supply. Applying new approaches is required in this situation to deal with water scarcity. Wadi Watir in the Sinai Peninsula, chosen as the research area, is an important tourist and commercial watershed. It experiences water scarcity and the threat of flash floods. The residents are losing their crops and sheep. Roads are deserted, and their lives are in danger due to the periodic occurrence of flash floods. Materials and methods. For the first time, the current research investigates the impact of flash floods on the implementation of rainwater harvesting (RWH) systems. The flash flood risk and RWH structure maps were overlaid using GIS. Results. The results showed that five percolation tanks, five check dams, 11.15 km2 of area for on-ground percolation tanks, and 0.48 km2 of space for farm ponds are optimal for water harvesting during flash floods. Conclusions. The development of Wadi Watir was prioritized and divided into three phases. Therefore, the occurrence of flash floods clearly affects the development plans. The impact of flash floods should be considered during the calculation of the design capacity of the RWH structures.

Spatial analysis of flash flood and Drought impact from Climate Change in Phongsaly District, Phogsaly Province, by using Geo-Informatics Technology and Modelling

A method for predicting the water resource in the region in the future to be used as a basis for mitigating the consequences is to study how climate change affects hydrology. The purpose of this study is to i). choose a global climate model that is suitable for the area, ii). rainfall run-off modelling, iii). drought and flood hazard index map. The SSP-126, SSP-245, and SSP-585 scenarios were chosen as the most appropriate global climate model among the four institutes, with efficiency criteria using the coefficient of Nash-Sutcliffe and Kling-Gupta and then calibrate the data with the Bias Correction Linear Scaling method which divides the analysis period into 2 periods for Near-Future and Far-Future from analyzing Rainfall Run-off Modeling from Rainfall Concentration 1-hours, 3-hours and 6-hours. It was found that the SSP-585 scenario in the Rainfall Concentration 1-hours model has the most dangerous area for very high risk until the end of the 21st century. For the analysis of drought indices SPI_1, SPI_3 and SPI_6 in Near-Future, it was found that the frequency of droughts is increasing according to the worst scenario, the scenario with the most drought is SSP-585 and in the Far-Future, the frequency of drought is decreasing according to the worst scenario, the scenario with the most drought is SSP-126.

Failure criteria of unreinforced masonry walls of rural buildings under the impact of flash floods in mountainous regions

Failure criteria of unreinforced masonry walls of rural buildings under the impact of flash floods in mountainous regions

Managing a road as a river to mitigate the impact of urban flash floods

Managing a road as a river to mitigate the impact of urban flash floods

Impact of Flash Floods On Agri-based Livelihoods In Sylhet Haor Basin

Bangladesh is most vulnerable to natural disasters and climate change. Over the past few decades, flash floods have frequently affected the livelihood of people in the Sylhet Haor Basin. This study highlights the causes of increased flash floods, their impact on farming practices and livelihoods, and possible solutions to flash flood risk in the Sylhet Haor Basin. Data were collected using a pre-tested structured questionnaire from randomly selected 298 Haor farmers in high and moderately vulnerable flash flood zones across the Haor region during November 2021 and April 2022. In moderately vulnerable areas, the lack of rivers and canal dredging was the main factor contributing to flash flood deterioration. Index scores and ranks revealed that flash floods most severely affect the primary production sector (agriculture) and threaten the lives and livelihoods of the local populace in high- and moderately flood-prone areas. After the severe flash flood, farmers were forced to turn to other occupations instead of agriculture for their livelihood. To reduce the impact of flash floods on particular features or entire wetlands, most farmers preferred the construction of embankments over sandbags, concrete or stone dams, submergible embankments, and rubber dams. For flash flood risk management, farmers in high- and moderately flash flood-vulnerable areas emphasize the construction of higher dams and embankments and the installation of more flood barriers (dams/embankments). The concerned flash flood management agencies could incorporate the key findings of this study while formulating risk mitigation strategies for the Sylhet Haor Basin. Ann. Bangladesh Agric. (2022) 26 (1) : 61-73

Assessing the risk posed by flash floods to the transportation network in southwestern China

Flash flood can cause dramatic damages to the infrastructure of transportation networks. Because of the uncertainty of flash floods and the access function of roads, assessing the impact of flash floods on transportation systems has been a great challenge. In this study, we proposed a framework for evaluating the risk posed by flash floods to transportation network, which considers the interruption probability of road links and the expected impact on the access function of transportation. To assess the probability of interruption, we used the random forest model to output the flash floods susceptibility. Then, a multiple centrality model was used to evaluate the expected impact when a link was interrupted. The risk takes into account the flash floods susceptibility and road multiple centrality, and it identify critical links. Using the natural break points method, the result of flash floods susceptibility, road multiple centrality and risk were divided into five levels: extremely low, low, moderate, high and extremely high. Approximately 30.8% of the roads were found to be at high and extremely high risk, and most of these roads were located in Sichuan and Yunnan provinces. The flash floods susceptibility contributes more to the risk than the road multiple centrality, thus, further study should be focused on the areas with high flash floods susceptibility. We discussed different disaster prevention and mitigation measures for the different types of high risk links. The results can improve our understanding of the risks posed by flash floods to road networks. The proposed generalized network risk analysis method provides a new perspective and tool for analysing the impact of flash floods on road network.

Environmental and economic impact of cloudburst-triggered debris flows and flash floods in Uttarakhand Himalaya: a case study

This paper examines the environmental and economic impact of cloudburst-triggered debris flow and flash flood in four villages of Uttarkashi district, Uttarakhand Himalaya. On 18th July 2021 at 8:30 p.m., a cloudburst took place on the top of the Hari Maharaj Parvat, which triggered a huge debris flows and flash floods, affecting 143 households of four villages of downstream areas. Immediately after the cloudburst occurred, the authors visited four affected villages—Nirakot, Mando, Kankrari, and Siror. A structured questionnaire was constructed and questions were framed and asked from 143 heads of affected households on the impact of debris flows and flash floods on people’s life, settlements, cowsheds, bridges, trees, forests, and arable land in and around the villages. The volume of debris, boulders, pebbles, gravels, and mud was assessed. It was noticed that all four villages got lots of destructions in terms of loss of life—people and animals, and property damage—land, crops, and infrastructural facilities. This study shows that the location of the settlements along with the proximity of the streams, which are very violent during the monsoon season, has led to the high impact of debris flow on the affected villages. We suggest that the old inhabited areas, which are located in the risk zones, can be relocated and the new settlements can be constructed in safe places using suitability analyses.

Alleviation approach for flash flood risk reduction in urban dwellings: A case study of Fifth District, Egypt

Flash Floods resemble one of the most strenuous challenges that we face in the 21st century. Therefore, identifying the flooded areas is imperative to avert the negative consequences. An enormous number of researchers tended to study the impact of flash floods on vast areas which puts up some challenges if we want to address this deleterious effect of flash floods on small urban cities. This research focused on investigating and mitigating the devastating effect of flash floods on Fifth District– Egypt where the flash flood strikes many times a year. Furthermore, the study was developed on both community and building scale. The purpose of studying the community scale is to assess the risk level that may occur during certain predicted hydrographs. Moreover, this study was also conducted on a building scale to examine the effect of water excess on buildings and how many buildings are in the flood streamlines. The water depth was calculated in front of each building to make fully appraisal on the buildings state. Moreover, 32 underground tanks were utilized as protective measures. These tanks were located at the streamlines where the water flow accumulates. After applying the mitigation measures, the water depth decreased in the main streamlines as well as 153 m3 of the rainfall water was collected and could be reused after treatment. Eventually, the analytical hierarchy process was used to generate the weights of each component of flood hazard map. This map is essential to determine the most prone areas in the studied region.

Compound flood impact forecasting: integrating fluvial and flash flood impact assessments into a unified system

Abstract. Floods can arise from a variety of physical processes. Although numerous risk assessment approaches stress the importance of taking into account the possible combinations of flood types (i.e. compound floods), this awareness has so far not been reflected in the development of early warning systems: existing methods for forecasting flood hazards or the corresponding socio-economic impacts are generally designed for only one type of flooding. During compound flood events, these flood type-specific approaches are unable to identify overall hazards or impacts. Moreover, from the perspective of end-users (e.g. civil protection authorities), the monitoring of separate flood forecasts – with potentially contradictory outputs – can be confusing and time-consuming, and ultimately impede an effective emergency response. To enhance decision support, this paper proposes the integration of different flood type-specific approaches into one compound flood impact forecast. This possibility has been explored through the development of a unified system combining the simulations of two impact forecasting methods: the Rapid Risk Assessment of the European Flood Awareness System (EFAS RRA; representing fluvial floods) and the radar-based ReAFFIRM method (representing flash floods). The unified system has been tested for a recent catastrophic episode of compound flooding: the DANA event of September 2019 in south-east Spain (Depresión Aislada en Niveles Altos, meaning cut-off low). The combination of the two methods identified well the overall compound flood extents and impacts reported by various information sources. For instance, the simulated economic losses amounted to about EUR 670 million against EUR 425 million of reported insured losses. Although the compound impact estimates were less accurate at municipal level, they corresponded much better to the observed impacts than those generated by the two methods applied separately. This demonstrates the potential of such integrated approaches for improving decision support services.

Flash Flood Susceptibility Mapping of Sungai Pinang Catchment using Frequency Ratio

Flash flood are natural disasters that frequently occur in Malaysia especially in urban areas. Due to this, the development of flash flood susceptibility mapping one of the tools used to aid the local authority in reducing and managing the flash flood impact. Frequency Ratio (FR) is a popular method in predictive modeling because of its capabilities to determine the critical conditioning factor of flash flood. The aim of this research was to compare the standalone FR with Ensemble FR-AHP. This ensemble method uses pair-wise comparison method between Frequency Ratio and Analytical Hierarchy Process (AHP). For this research, ten conditioning factors were selected which were slope, aspect, curvature, Topographic Wetness Index (TWI), Stream Power Index (SPI), Normalized Difference Vegetation Index (NDVI), distance from river, rainfall, elevation, and land use/land cover (LULC). The flash flood inventory was obtained from local authorities where the flash flood occurred in Penang, Malaysia on November 2017. 70% of 110 flooded locations were used as training dataset to assess the spatial distribution of flooding whereas the remaining 30% flooded locations were used as validation dataset. Based on the results, the prediction rate of FR-AHP method is slightly better accuracy compared to FR method which 88.33% (FR-AHP) and 85.62% (FR). The output of this research is crucial to assist local authority in land use planning and drainage system of the study area.

Original

Flash flood is a common disaster in northeastern haor areas of Bangladesh. It frequently affects the life and livelihood of haor people every year. Women are the most vulnerable in this catastrophic situation compared to men. The present study attempted to explore the effects of flash floods on women at Tahirpur Upazila in the Sunamganj district. A semi-structured questionnaire survey on 172 married women chosen from four villages, seven focus group interviews, and ten key informant interviews was conducted for primary data collection. A Flash Flood Impact Ranking (FFIR) was also prepared to grade the impacts on women based on a 3-points weighted severity scale. The study findings revealed that women suffered from different diseases with physical injuries and faced many difficulties managing the shelter, food, safe water, sanitation, and fuel for cooking during the flood. The FFIR displayed that crops damage, lack of funds, job opportunities, sanitation problems, and food insecurities were the top five disaster impacts on women. It is suggested that Government and other agencies should increase women's coping strategies by ensuring health services and employment opportunities to mitigate damage and flash flood-related problems.

The socioeconomic impact of climate-related hazards: flash flood impact assessment in Kuala Lumpur, Malaysia

The socioeconomic impact of climate-related hazards: flash flood impact assessment in Kuala Lumpur, Malaysia

Analytical traveling-wave solutions and HYDRUS modeling of wet wedges propagating into dry soils: Barenblatt's regime for Boussinesq's equation generalized

The classical Barenblatt solution of an initial-boundary value problem (IBVP) to the parabolic Boussinesq equation, which gives a rectangular triangle of full saturation, propagating from a reservoir into an adjacent porous bank with a vertical slope, is shown to coincide with a solution of IBVP to the elliptic Laplace equation with a phreatic surface along which both isobaricity and kinematic conditions are exactly met. For an arbitrary bank slope, a saturated wedge, which propagates (translates) into dry soil, is also explicitly found. The analytical solutions favorably compare with the results of HYDRUS-2D modeling, i.e., with the FEM solutions of the same IBVPs to the Richards equation. Applications to geotechnical engineering of dykes subject to the impact of flash floods are discussed by comparisons of phreatic lines, loci of the fronts, isobars, equipotential contours, vector fields of Darcian velocity, isotachs, and streamlines in the three models. For example, it is shown that a rapid drawup of the reservoir level induces hydraulic gradients, which may cause seepage-induced erosion of the porous medium, in particular, lessivage.

Nonlinear Simulation and Vulnerability Analysis of Masonry Structures Impacted by Flash Floods

The vulnerability of buildings impacted by flash floods is often assessed by empirical approaches. However, the damage-developing mechanisms of buildings remain unclear. This study presented a nonlinear numerical analysis for the interaction between flash floods and masonry structures. A new Structured ALE (S-ALE) solver in an explicit finite element platform LS-DYNA was applied. Thirty different scenarios, including two different FE models, three different water depths, and five different flow velocities, were studied. Nonlinear structural responses and failure mechanisms of masonry structures were analyzed and compared. Results showed that due to the consideration of wall damage, the time evolution of the impact force on the entire building was distributed in a multipeak pattern. Under the impact of flash floods, the building was in a complex bending-shear state, and the overturning moment was the principal reason for the building damage. The critical role played by the structural measure was reaffirmed. Moreover, the physical vulnerability was quantified through a macroscopic damage index, the lateral drift ratio of the ground floor. It can be concluded that the physical vulnerability depends on both the local structural strength (local view) and the structural resistance hierarchies (global view).