Spatiotemporal Variation of Flash Floods in the Hengduan Mountains Region Affected by Rainfall Properties and Land-use

2021 ◽  
Author(s):  
Xiaoyun Sun ◽  
Guotao Zhang ◽  
Jiao Wang ◽  
Chaoyue Li ◽  
Shengnan Wu ◽  
...  
Keyword(s):  
Land Use ◽  
High Risk ◽  
Heavy Rainfall ◽  
Flash Flood ◽  
Linear Trend ◽  
Flash Floods ◽  
Spatiotemporal Variation ◽  
Hengduan Mountains ◽  
Flood Events ◽  
Accurate Identification

Abstract Understanding the spatiotemporal characteristic of flash floods is significant for the reasonable and accurate identification of high-risk regions of disasters as well as future prediction of hydrological regimes. Therefore, this study collected time-series datasets (1979-2015) of historical flash flood events, rainfall, and land-use in the Hengduan Mountains region, China to characterize the spatiotemporal variation in flash floods affected by the change in rainfall and land-use. Using linear trend, a significant increase with 12 times/10a for flash flood events was found while 82% of events occurred in the flood season (June–August). They were closely related to the increase in frequency (3.5 d/10a) and magnitude (215.55 mm/10a) of heavy rainfall as well as the amplified artificial (999 km2). Affected by heavy rainfall due to climate change and human activity, significant periodic variations on the scales of 3-7a, 8-15a, and 21-31a were derived based on the Morlet wavelet analysis. Meanwhile, utilizing the standard elliptical difference, we identified the moving route of the gravity center of flash floods, with the direction from northwest to southeast. More recorded disasters generally were found in the south of the Hengduan Mountain region, where was mainly controlled by frequent rainstorms and the formation of more cropland and artificial with higher runoff potential. These findings can be an appropriate supplement for lack of understanding of the spatiotemporal dynamics of flash floods in the Hengduan Mountains region and could provide policymakers with evidence to identify high-risk areas which is difficult to cope with in the mountainous watershed.

scholarly journals Spatiotemporal variation of flash floods in the Hengduan Mountains region affected by rainfall properties and land use

2021 ◽  
Author(s):  
Xiaoyun Sun ◽  
Guotao Zhang ◽  
Jiao Wang ◽  
Chaoyue Li ◽  
Shengnan Wu ◽  
...  
Keyword(s):  
Land Use ◽  
Flash Floods ◽  
Spatiotemporal Variation ◽  
Hengduan Mountains

Methodology for risk assessment of flash flood events due to climate and land use changes

2012 ◽  
Author(s):  
M Velasco ◽  
A Cabello ◽  
I Escaler ◽  
J Barredo ◽  
A Barrera-Escoda
Keyword(s):  
Risk Assessment ◽  
Land Use ◽  
Flash Flood ◽  
Land Use Changes ◽  
Flood Events

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 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.

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 APPLICATION GIS AND REMOTE SENSINGTO ESTABLISH FLASH FLOOD HAZARD MAP IN TUYEN QUANG PROVINCE

2021 ◽  
Vol 7 (21) ◽  
pp. 142-149
Author(s):  
Văn Trần Đức
Keyword(s):  
High Risk ◽  
Flash Flood ◽  
Flood Hazard ◽  
High Reliability ◽  
Flash Floods ◽  
Hazard Map ◽  
Gis And Remote Sensing ◽  
Rivers And Streams ◽  
Flood Hazard Map ◽  
Hazard Level

Tuyen Quang is one of the provinces at high risk of flash floods in the Northern Midlands and Mountains of Vietnam. In the rainy season, like other localities in the region, Tuyen Quang has a long, concentrated rainfall combined with steep hills and mountains, large divisions, many rivers, and streams; In addition, the thinning of the vegetation cover due to excessive exploitation of the forest by the local people causes flash floods to appear more and more. Applying GIS and remote sensing to establish a map of flash flood risk is a quantitative approach and high reliability. This article has established a flash flood hazard map at a scale of 1/100,000 in Tuyen Quang province. In the map database, districts with a high risk of flash flood were identified, including Na Hang, Chiem Hoa, Ham Yen, and Lam Binh, the average flash flood hazard level included districts: Yen Son, Son Duong; Tuyen Quang city has a low risk of flash floods.

scholarly journals Flash Flood Susceptibility Mapping at Andungbiru Watershed, East Java Using AHP-Information Weighted Method

2021 ◽  
Vol 6 (2) ◽  
pp. 127
Author(s):  
Devi Ratna Handini ◽  
Entin Hidayah ◽  
Gusfan Halik
Keyword(s):  
Land Use ◽  
Vegetation Index ◽  
Flash Flood ◽  
Characteristic Curve ◽  
Flash Floods ◽  
Assessment Method ◽  
Economic Losses ◽  
Landsat 8 ◽  
Gis Technology ◽  
Topographic Wetness Index

Flash floods are among the most frequent natural disasters caused by heavy rain associated with a severe thunderstorm, which leads to social and economic losses in infrastructure and agriculture. Therefore, this research aims to map flash flood potential susceptibility (FFPS) in the Pekalen watershed, using Geographic Information System (GIS) technology and statistical analysis to reduce the risk of flooding. The opinion and experience of an expert on the weight assessment method were carried out using the Analytical Hierarchy Process (AHP). Furthermore, the probability statistical methods and GIS were used in flash flood areas in the Pekalen watershed in Andungbiru, Probolinggo village. This study was carried out using geomorphological factors, namely elevation, slope, stream power index, and topographic wetness index, with a resolution of 30 m. Thematic map scale of the land use, river density, distance to the river, rainfall, and geology is in the ratio of is in a ratio of 1:25.000. Imagery processing was carried out using Landsat 8 30 m x 30 m resolution imagery, such as the Normalized Difference Vegetation Index. The result showed that the model map of FFPS obtained low 8%, low 23%, moderate 27%, moderate to high 26%, high 13%, and very high 2% index values. The next stage of modeling analysis led to validation using statistic receiver operating Characteristic Curve (ROC) of area Under Curve (AUC) with a value of 90.15. In conclusion, the factors that significantly trigger flash floods are distance to the river, land use, and slope.   Keywords: AHP-weighted; information content; FFSP; GIS; Geomorphology Copyright (c) 2021 Geosfera Indonesia and Department of Geography Education, University of Jember   This work is licensed under a Creative Commons Attribution-Share A like 4.0 International License

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.

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