scholarly journals Analysis of Human Activity Impact on Flash Floods in China from 1950 to 2015

2020 ◽  
Vol 13 (1) ◽  
pp. 217
Author(s):  
Yesen Liu ◽  
Yaohuan Huang ◽  
Jinhong Wan ◽  
Zhenshan Yang ◽  
Xiaolei Zhang
Keyword(s):  
Air Quality ◽  
Human Activities ◽  
Vegetation Cover ◽  
Flash Flood ◽  
Flash Floods ◽  
Temporal Variations ◽  
Flood Events ◽  
Rapid Variation ◽  
Flash Flooding ◽  
Anthropogenic Intervention

An early warning of a flash flood is essential to prevent the general public from the hazardous flooding events, however, the rapid variation of human activities has led to the uncertainty of risk in prone areas. The lack of a systematic record of flash flood events introduces challenges to flash flood-related research. Herein, we map spatial and temporal variations in flash floods in China from 1950 to 2015 and establish a general ordered logit model in a geographic information environment to estimate the association between the occurrence of flash flood events and natural conditions and the variation of human activities at the watershed level. The results showed that precipitation is an important cause of flash flooding, and demonstrate that anthropogenic intervention (heavy rainfall, density of villages, and vegetation cover) in the environment affect the likelihood of flash floods. We found that the likelihood of flash floods in China may increase with the air quality worsening and that the occurrence of flash floods is strongly correlated with vegetation cover. Our findings suggest a need for further investigation of the link between air quality and flash flooding in flood-prone areas.

scholarly journals Effectiveness of the Submersible Embankment in Haor Area in Bangladesh

2018 ◽  
Vol 13 (4) ◽  
pp. 780-792
Author(s):  
Mohammad Hossain Mahtab ◽  
Miho Ohara ◽  
Mohamed Rasmy ◽  
◽  
Keyword(s):  
Flash Flood ◽  
Flash Floods ◽  
Rainfall Runoff ◽  
Flood Events ◽  
Monsoon Period ◽  
Flash Flooding ◽  
The North ◽  
North Eastern ◽  
Embankment Height ◽  
North Eastern Part

The north-eastern part of Bangladesh is very productive for agriculture and fishing, and the region involves several depressed (haor) areas. Flash floods during the pre-monsoon period bring devastating damage to agriculture in the haor region recurrently. To protect crops from flash floods, the Bangladesh Water Development Board constructed several ring-type submersible embankments. In this research, we have investigated the effectiveness of submersible embankments in controlling flash flooding in the Matian and Shanir haors in the Sunamganj district. A two-dimensional rainfall runoff inundation model was applied considering several scenarios for simulating heavy flash flood events in 2004, 2010, and 2016. Without an embankment, the river overflow would have entered the Matian haor 3 days, 22 days, and 9 days earlier in 2004, 2010, and 2016, respectively, whereas it would have been 7 days and 23 days earlier in 2004 and 2010 for the Shanir haor. The event in 2016 was successfully stopped by the Shanir haor embankment. To avoid river overflow entering into the Matian and Shanir haor completely, the embankment height must be elevated further by 1 m and 0.7 m, respectively. Providing proper drainage facilities for the accumulated rain water inside the hoar is still an important issue for protecting the crops effectively.

Effects of 2017 Early Flash Flooding on Agriculture in Haor Areas of Sunamganj

2021 ◽  
Vol 12 (1-2) ◽  
pp. 117-125
Author(s):  
S Mondal ◽  
L Akter ◽  
HJ Hiya ◽  
MA Farukh
Keyword(s):  
Agricultural Production ◽  
Flash Flood ◽  
Eastern Region ◽  
Fish Production ◽  
Flood Events ◽  
Flash Flooding ◽  
The North ◽  
North Eastern ◽  
Boro Rice

The Sunamganj district is covered by major Haor systems in the north-eastern region of Bangladesh. Flash flood is the most commonly occurring water related disaster in the Haor areas. During the flash flood it is very common that people lost their primary agricultural productions which are the only source of their livelihood. The present study focuses on the effects of 2017 early flash flooding on rice and fish production of Sunamganj Haor areas. The flood caused enormous damage to agriculture such as rice especially Boro rice and fish production on which the Haor dwellers rely upon for their livelihood. The total affected land of Boro rice cultivation in Haors of Sunamganj was 149,224 hectare and the total amount of damaged rice was 393,855 metric ton (MT). The total number of affected farmers was 315,084. The early flash flood also affects the quality of Haor water which caused the death of fishes. The total amount of damaged fish was 49.75 MT and the loss was 158.70 lakh taka. The total number of affected fishermen was 44,445. This findings could be very useful for the environmental scientists to predict the probable future effects on agricultural production due to early flash flood events in Sunamganj Haors areas. Environ. Sci. & Natural Resources, 12(1&2): 117-125, 2019

scholarly journals Post-event analysis and flash flood hydrology in Slovakia

2016 ◽  
Vol 64 (4) ◽  
pp. 304-315 ◽  
Author(s):  
Kamila Hlavčová ◽  
Silvia Kohnová ◽  
Marco Borga ◽  
Oliver Horvát ◽  
Pavel Šťastný ◽  
...  
Keyword(s):  
Hydrological Model ◽  
Flash Flood ◽  
Flash Floods ◽  
Event Analysis ◽  
Distributed Hydrological Model ◽  
Rainfall Runoff ◽  
Flood Events ◽  
Spatially Distributed ◽  
Catchment Size ◽  
Flood Peaks

Abstract This work examines the main features of the flash flood regime in Central Europe as revealed by an analysis of flash floods that have occurred in Slovakia. The work is organized into the following two parts: The first part focuses on estimating the rainfall-runoff relationships for 3 major flash flood events, which were among the most severe events since 1998 and caused a loss of lives and a large amount of damage. The selected flash floods occurred on the 20th of July, 1998, in the Malá Svinka and Dubovický Creek basins; the 24th of July, 2001, at Štrbský Creek; and the 19th of June, 2004, at Turniansky Creek. The analysis aims to assess the flash flood peaks and rainfall-runoff properties by combining post-flood surveys and the application of hydrological and hydraulic post-event analyses. Next, a spatially-distributed hydrological model based on the availability of the raster information of the landscape’s topography, soil and vegetation properties, and rainfall data was used to simulate the runoff. The results from the application of the distributed hydrological model were used to analyse the consistency of the surveyed peak discharges with respect to the estimated rainfall properties and drainage basins. In the second part these data were combined with observations from flash flood events which were observed during the last 100 years and are focused on an analysis of the relationship between the flood peaks and the catchment area. The envelope curve was shown to exhibit a more pronounced decrease with the catchment size with respect to other flash flood relationships found in the Mediterranean region. The differences between the two relationships mainly reflect changes in the coverage of the storm sizes and hydrological characteristics between the two regions.

scholarly journals Impact of Flash Flood Events on the Coastal Waters Around Madeira Island: The “Land Mass Effect”

2022 ◽  
Vol 8 ◽  
Author(s):  
Alexandra Rosa ◽  
Cláudio Cardoso ◽  
Rui Vieira ◽  
Ricardo Faria ◽  
Ana R. Oliveira ◽  
...  
Keyword(s):  
Chlorophyll A ◽  
Coastal Waters ◽  
Flash Flood ◽  
Mass Effect ◽  
Flash Floods ◽  
River Plume ◽  
Flood Events ◽  
Madeira Island ◽  
The Impact ◽  
Land Runoff

The Island Mass Effect has been primarily attributed to nutrient enhancement of waters surrounding oceanic islands due to physical processes, whereas the role of land runoff has seldom been considered. Land runoff can be particularly relevant in mountainous islands, highly susceptible to torrential rainfall that rapidly leads to flash floods. Madeira Island, located in the Northeast Atlantic Ocean, is historically known for its flash flood events, when steep streams transport high volumes of water and terrigenous material downstream. A 22-year analysis of satellite data revealed that a recent catastrophic flash flood (20 February 2010) was responsible for the most significant concentration of non-algal Suspended Particulate Matter (SPM) and Chlorophyll-a at the coast. In this context, our study aims to understand the impact of the February 2010 flash flood events on coastal waters, by assessing the impact of spatial and temporal variability of wind, precipitation, and river discharges. Two specific flash floods events are investigated in detail (2 and 20 February 2010), which coincided with northeasterly and southwesterly winds, respectively. Given the lack of in situ data documenting these events, a coupled air-sea-land numerical framework was used, including hydrological modeling. The dynamics of the modeled river plumes induced by flash floods were strongly influenced by the wind regimes subsequently affecting coastal circulation, which may help to explain the differences between observed SPM and Chlorophyll-a distributions. Model simulations showed that during northeasterly winds, coastal confinement of the buoyant river plume persisted on the island’s north coast, preventing offshore transport of SPM. This mechanism may have contributed to favorable conditions for phytoplankton growth, as captured by satellite-derived Chlorophyll-a in the northeastern coastal waters. On the island’s south coast, strong ocean currents generated in the eastern island flank promoted strong vertical shear, contributing to vertical mixing. During southwesterly winds, coastal confinement of the plume with strong vertical density gradient was observed on the south side. The switch to eastward winds spread the south river plume offshore, forming a filament of high Chlorophyll-a extending 70 km offshore. Our framework demonstrates a novel methodology to investigate ocean productivity around remote islands with sparse or absent field observations.

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

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

scholarly journals A Temporally Varied Rainfall Simulator for Flash Flood Studies

2021 ◽  
pp. 267-279
Author(s):  
Mohammad Ebrahim Banihabib ◽  
Bahman Vaziri
Keyword(s):  
Numerical Model ◽  
Flash Flood ◽  
Experimental Studies ◽  
Temporal Distribution ◽  
Field Studies ◽  
Flash Floods ◽  
Flash Flooding ◽  
Rainfall Simulator ◽  
Natural Rainfall ◽  
Precipitation Events

AbstractExperimental studies of flash floods require rainfall simulations. For this reason, various rainfall simulators have been designed, built, and employed in previous studies. These previous rainfall simulators have provided good simulations of constant rainfall intensities; however, these simulators cannot generate temporally varied rainstorms. Thus, the effect of the temporal distribution of a rainstorm on flash flooding cannot be studied using current rainfall simulators. To achieve accurate and reliable results in flash flood studies, simulating rainstorms that are similar to natural precipitation events is essential, and natural rainfall varies temporally. Thus, a rainstorm simulator was designed and built using cascading tanks to generate rainstorm hyetographs that cannot be obtained using traditional rainfall simulators. The result of the rainstorm generated by the proposed instrument and its numerical model showed that the instrument can simulate the temporal distributions of rainstorms with an accuracy of 95 percent. Consequently, the proposed instrument and its numerical model can be applied for generating artificial rainstorm hyetographs in experimental and field studies of flash floods.

scholarly journals Bias Correction of Satellite-Based Rainfall Estimates for Modeling Flash Floods in Semi-Arid regions: Application to Karpuz River, Turkey

2016 ◽  
Author(s):  
Mohamed Saber ◽  
Koray Yilmaz
Keyword(s):  
Bias Correction ◽  
Flash Flood ◽  
Flash Floods ◽  
Rainfall Rate ◽  
Assessment Model ◽  
Model Parameters ◽  
Flood Events ◽  
Rain Gauges ◽  
Semi Arid ◽  
Rainfall Estimates

Abstract. This study investigates the utility of gauge-corrected satellite-based rainfall estimates in simulating flash floods at Karpuz River - a semi-arid basin in Turkey. Global Satellite Mapping of Precipitation (GSMaP) product was evaluated with the rain gauge network at monthly and daily time-scales considering various time periods and rainfall rate thresholds. Statistical analysis indicated that GSMaP shows acceptable linear correlation coefficient with rain gauges however suffers from significant underestimation bias. A rainfall rate threshold of 1 mm/month was the best choice to improve the match between GSMaP and rain gauges implying that appropriate threshold selection is critically important for the bias correction. Multiplicative bias correction was applied to GSMaP data using the bias factors calculated between GSMaP and observed rainfall. Hydrological River Basin Environmental Assessment Model (Hydro-BEAM) was used to simulate flash floods at the hourly time scale driven by the corrected GSMaP rainfall data. The model parameters were calibrated for flash flood events during October-December 2007 and then validated for flash flood events during October-December 2009. The results show that the simulated surface runoff hydrographs reasonably coincide with the observed hydrographs.

scholarly journals More frequent flash flood events and extreme precipitation favouring atmospheric conditions in temperate regions of Europe

2021 ◽  
Author(s):  
Judith Meyer ◽  
Malte Neuper ◽  
Luca Mathias ◽  
Erwin Zehe ◽  
Laurent Pfister
Keyword(s):  
Extreme Precipitation ◽  
Western Europe ◽  
Flash Flood ◽  
Flash Floods ◽  
Water Levels ◽  
Specific Humidity ◽  
Atmospheric Conditions ◽  
Flood Events ◽  
Extreme Precipitation Events ◽  
Precipitation Events

Abstract. In recent years, flash floods repeatedly occurred in temperate regions of central western Europe. Unlike in Mediterranean catchments, this flooding behaviour is unusual. In the past, and especially in the 1990s, floods were characterized by predictable, slowly rising water levels during winter and driven by westerly atmospheric fluxes (Pfister et al., 2004). The intention of this study is to link the recent occurrence of flash floods in central western Europe to extreme precipitation and specific atmospheric conditions to identify the cause for this apparent shift. Therefore, we hypothesise that an increase in extreme precipitation events has subsequently led to an increase in the occurrence of flash flood events in central western Europe and all that being caused by a change in the occurrence of flash flood favouring atmospheric conditions. To test this hypothesis, we compiled data on flash floods in central western Europe and selected precipitation events above 40 mm h−1 from radar data (RADOLAN, DWD). Moreover, we identified proxy parameters representative for flash flood favouring atmospheric conditions from the ERA5 reanalysis dataset. High specific humidity in the lower troposphere (q ≥ 0.004 kg kg−1), sufficient latent instability (CAPE ≥ 100 J kg−1) and weak deep-layer wind shear (DLS ≤ 10 m s−1) proved to be characteristic for long-lasting intense rainfall that can potentially trigger flash floods. These atmospheric parameters, as well as the flash flood and precipitation events were then analysed using linear models. Thereby we found significant increases in atmospheric moisture contents and increases in atmospheric instability. Parameters representing the motion and organisation of convective systems occurred slightly more often or remained unchanged in the time period from 1981–2020. Moreover, a trend in the occurrence of flash floods was confirmed. The number of precipitation events, their maximum 5-minute intensities as well as their hourly sums were however characterized by large inter-annual variations and no trends could be identified between 2002–2020. This study therefore shows that the link from atmospheric conditions via precipitation to flash floods cannot be traced down in an isolated way. The complexity of interactions is likely higher and future analyses should include other potentially relevant factors such as intra-annual precipitation patterns or catchment specific parameters.

Identifying and linking flash flood prone atmospheric conditions to flooding occurrences in central Western Europe

2021 ◽  
Author(s):  
Judith Meyer ◽  
Audrey Douinot ◽  
Malte Neuper ◽  
Luca Mathias ◽  
Carol Tamez-Meléndez ◽  
...  
Keyword(s):  
River Basin ◽  
Western Europe ◽  
Flash Flood ◽  
Flash Floods ◽  
Precipitation Data ◽  
Atmospheric Conditions ◽  
Flood Events ◽  
Atmospheric Parameters ◽  
Circulation Patterns ◽  
Daily Precipitation Data

<p>In recent years, flash floods occurred repeatedly in temperate regions of central Western Europe (e.g., Orlacher Bach (GER), Hupselsebeek (NL), White Ernz (LUX)). This type of extreme flood events is unusual for these regions, as opposed to Mediterranean catchments that are more prone to flash floods. In the second half of the 20<sup>th</sup> century, and more specifically in the 1990’s, westerly atmospheric fluxes were the dominating triggering factor of large scale (winter) floods in central Western Europe.</p><p>With a view to gain a better understanding of the mechanisms controlling the recent flash flood events at higher latitudes, we explore various avenues related to the non-stationarity of environmental systems. We hypothesize that an increase in the occurrence of flash flood prone atmospheric conditions has recently led to higher precipitation totals and a subsequent increase in flash flood events in central Western Europe.</p><p>Therefore, we first analysed relevant atmospheric parameters from the ERA 5 reanalysis dataset. Second, we linked the atmospheric parameters to the concept of general circulation patterns as per Hess and Brezowsky (1977). Third, we analysed precipitation data from a set of stations located in the Moselle river basin (35.000 km<sup>2</sup>). These three pillars build the base for identifying flash flood prone atmospheric conditions over space and time that are then compared to actual occurrences of extreme discharge events in streams within the Moselle river basin.</p><p>To validate our hypothesis, spatial and temporal patterns in the occurrence of extreme precipitation and discharge events need to match atmospheric patterns. Preliminary results suggest that daily precipitation data and meridional circulation patterns do not show a clear trend towards an increased occurrence of precipitation events or higher precipitation amounts. Due to the limitations inherent to the available long-term dataset of daily data, the hypothesis can only be partly evaluated, and more detailed analyses are added. For that reason, discharge data with a 15-minute resolution, along with precipitation radar data of 5-minute time steps will be employed at a limited spatial extent in future analyses. In case of rejection of our working hypothesis this may pinpoint to other flash flood triggering mechanisms, such as changes in land use, soil moisture conditions or cultivation methods.</p>

scholarly journals Evaluation of Tools Used for Monitoring and Forecasting Flash Floods in the United States

2012 ◽  
Vol 27 (1) ◽  
pp. 158-173 ◽  
Author(s):  
Jonathan J. Gourley ◽  
Jessica M. Erlingis ◽  
Yang Hong ◽  
Ernest B. Wells
Keyword(s):  
United States ◽  
Flash Flood ◽  
The United States ◽  
Flash Floods ◽  
Urban Setting ◽  
Flash Flooding ◽  
Flood Prediction ◽  
Critical Success ◽  
Monitoring And Forecasting ◽  
First Time

Abstract This paper evaluates, for the first time, flash-flood guidance (FFG) values and recently developed gridded FFG (GFFG) used by the National Weather Service (NWS) to monitor and predict imminent flash flooding, which is the leading storm-related cause of death in the United States. It is envisioned that results from this study will be used 1) to establish benchmark performance of existing operational flash-flood prediction tools and 2) to provide information to NWS forecasters that reveals how the existing tools can be readily optimized. Sources used to evaluate the products include official reports of flash floods from the NWS Storm Data database, discharge measurements on small basins available from the U.S. Geological Survey, and witness reports of flash flooding collected during the Severe Hazards Analysis and Verification Experiment. Results indicated that the operational guidance values, with no calibration, were marginally skillful, with the highest critical success index of 0.20 occurring with 3-h GFFG. The false-alarm rates fell and the skill improved to 0.34 when the rainfall was first spatially averaged within basins and then reached 50% of FFG for 1-h accumulation and exceeded 3-h FFG. Although the skill of the GFFG values was generally lower than that of their FFG counterparts, GFFG was capable of detecting the spatial variability of reported flash flooding better than FFG was for a case study in an urban setting.

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