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 A Statistical Comparison of the Properties of Flash Flooding and Nonflooding Precipitation Events in Portions of New York and Pennsylvania

2008 ◽  
Vol 23 (1) ◽  
pp. 114-130 ◽  
Author(s):  
Stephen M. Jessup ◽  
Arthur T. DeGaetano
Keyword(s):  
New York ◽  
Wind Direction ◽  
Flash Flood ◽  
Convective Available Potential Energy ◽  
Potential Temperature ◽  
Flash Floods ◽  
Antecedent Soil Moisture ◽  
Random Events ◽  
Rain Events ◽  
Precipitation Events

Abstract Flash floods reported for the forecast area of the National Weather Service Forecast Office at Binghamton, New York (BGM), are compared with similar significant precipitation and flash flood watch events not corresponding to flash flood reports. These event types are characterized by measures of surface hydrological conditions, surface and upper-air variables, thermodynamic properties, and proxies for synoptic-scale features. Flash flood and nonflood events are compared quantitatively via discriminant analysis and cross validation, and qualitatively via scatterplots and composite soundings. Results are presented in the context of a flash flood checklist used at BGM prior to this study. Flash floods and nonfloods are found to differ most significantly in antecedent soil moisture. The wind direction at 850 hPa shows differences between flood and nonflood events, with flooding more common for an easterly to southeasterly direction and nonflooding more common for a northwesterly direction. Southwesterly wind direction is characteristic of both types. In general, nonflooding significant precipitation events are more commonly associated with a better-defined ridge axis of relatively high 850-hPa equivalent potential temperature and larger convective available potential energy as compared to the flash flood events. Several parameters included on the BGM flash flood checklist, though effective at distinguishing significant precipitation events and flash floods from random events, were found to be unable to separate flash floods from nonflooding significant rain events.

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 The Spatiotemporal Distribution of Flash Floods and Analysis of Partition Driving Forces in Yunnan Province

2019 ◽  
Vol 11 (10) ◽  
pp. 2926 ◽  
Author(s):  
Junnan Xiong ◽  
Chongchong Ye ◽  
Weiming Cheng ◽  
Liang Guo ◽  
Chenghu Zhou ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Economic Development ◽  
Return Period ◽  
Driving Forces ◽  
Flash Flood ◽  
Temporal Distribution ◽  
Heavy Precipitation ◽  
Spatiotemporal Analysis ◽  
Flash Floods

Flash floods are one of the most serious natural disasters, and have a significant impact on economic development. In this study, we employed the spatiotemporal analysis method to measure the spatial–temporal distribution of flash floods and examined the relationship between flash floods and driving factors in different subregions of landcover. Furthermore, we analyzed the response of flash floods on the economic development by sensitivity analysis. The results indicated that the number of flash floods occurring annually increased gradually from 1949 to 2015, and regions with a high quantity of flash floods were concentrated in Zhaotong, Qujing, Kunming, Yuxi, Chuxiong, Dali, and Baoshan. Specifically, precipitation and elevation had a more significant effect on flash floods in the settlement than in other subregions, with a high r (Pearson’s correlation coefficient) value of 0.675, 0.674, 0.593, 0.519, and 0.395 for the 10 min precipitation in 20-year return period, elevation, 60 min precipitation in 20-year return period, 24 h precipitation in 20-year return period, and 6 h precipitation in 20-year return period, respectively. The sensitivity analysis showed that the Kunming had the highest sensitivity (S = 21.86) during 2000–2005. Based on the research results, we should focus on heavy precipitation events for flash flood prevention and forecasting in the short term; but human activities and ecosystem vulnerability should be controlled over the long term.

scholarly journals Spatio-Temporal Distribution of Flash Floods in Slovenia

Dela ◽  
2016 ◽  
pp. 5-39 ◽  
Author(s):  
Tajan Trobec
Keyword(s):  
Spatial Distribution ◽  
Temporal Distribution ◽  
Temporal Analysis ◽  
Flash Floods ◽  
Seasonal Distribution ◽  
Flash Flooding ◽  
Hilly Area ◽  
Spatio Temporal

This paper examines the spatial distribution of frequency of flash floods along with their seasonal distribution. The spatio-temporal analysis of past flash flooding covered 124 flash floods affecting areas of Slovenia between 1550 and 2015. Flash floods are most common in the mountainous and hilly area of northern Slovenia, which consists of alpine and a large part of subalpine landscapes. Autumnal flash floods occur across most of the country, while summer flash floods are seen mainly in the east. In most parts of the country autumnal flash floods predominate.

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.

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.

scholarly journals Spatial–temporal characteristics and driving factors of flash floods in Shaanxi Province considering regional differentiation

2021 ◽  
Author(s):  
Han Zhang ◽  
Jungang Luo ◽  
Jingyan Wu ◽  
Mengjie Yu
Keyword(s):  
Driving Forces ◽  
Flash Flood ◽  
Temporal Distribution ◽  
Flash Floods ◽  
Shaanxi Province ◽  
Regional Differentiation ◽  
Effective Prevention ◽  
Temporal Characteristics ◽  
Northern Shaanxi ◽  
And Control

Abstract Flash floods show strong regional differentiation in spatial–temporal distribution and driving forces, thereby hindering their effective prevention and control. This study analyzed the spatiotemporal characteristics of flash floods in Shaanxi Province, China, differentiated among the northern Shaanxi (NS), Guanzhong (GZ), and southern Shaanxi (SS) regions based on the Mann–Kendall, Theil–Sen Median, and standard deviation ellipse methods. The main factors driving disasters and their interactions in each region were then identified within the three categories of precipitation factor (PPF), surface environment factor, and human activity factor (HAF) based on a geographical detector. Finally, the differences in flash flood characteristics among the NS, GZ, and SS regions were analyzed. The results showed that flash floods in Shaanxi Province are greatly affected by the PPF and the HAF, although the spatial–temporal characteristics and disaster-causing factors were significantly different in each region. The regions were ranked according to the number and growth trends of flash floods as follows: SS > GZ > NS. Furthermore, flash floods were affected by multiple factors, with the interaction between factors acting as a driving force of flash floods. The results of this study can provide a reference for the management of flash floods under regional differentiation.

scholarly journals Double Impact: When Both Tornadoes and Flash Floods Threaten the Same Place at the Same Time

2015 ◽  
Vol 30 (6) ◽  
pp. 1673-1693 ◽  
Author(s):  
Erik R. Nielsen ◽  
Gregory R. Herman ◽  
Robert C. Tournay ◽  
John M. Peters ◽  
Russ S. Schumacher
Keyword(s):  
Mississippi River ◽  
Flash Flood ◽  
Flash Floods ◽  
Public Communication ◽  
Synoptic Scale ◽  
Flash Flooding ◽  
Synoptic Conditions ◽  
Lower Mississippi River ◽  
Double Impact ◽  
Flood Warnings

Abstract While both tornadoes and flash floods individually present public hazards, when the two threats are both concurrent and collocated (referred to here as TORFF events), unique concerns arise. This study aims to evaluate the climatological and meteorological characteristics associated with TORFF events over the continental United States. Two separate datasets, one based on overlapping tornado and flash flood warnings and the other based on observations, were used to arrive at estimations of the instances when a TORFF event was deemed imminent and verified to have occurred, respectively. These datasets were then used to discern the geographical and meteorological characteristics of recent TORFF events. During 2008–14, TORFF events were found to be publicly communicated via overlapping warnings an average of 400 times per year, with a maximum frequency occurring in the lower Mississippi River valley. Additionally, 68 verified TORFF events between 2008 and 2013 were identified and subsequently classified based on synoptic characteristics and radar observations. In general, synoptic conditions associated with TORFF events were found to exhibit similar characteristics of typical tornadic environments, but the TORFF environment tended to be moister and have stronger synoptic-scale forcing for ascent. These results indicate that TORFF events occur with appreciable frequency and in complex meteorological scenarios. Furthermore, despite these identified differences, TORFF scenarios are not easily distinguishable from tornadic events that fail to produce collocated flash flooding, and present difficult challenges both from the perspective of forecasting and public communication.

The 23 June 2016 West Virginia Flash Flood Event as Observed through Two Hydrometeorology Testbed Experiments

2020 ◽  
Vol 35 (5) ◽  
pp. 2099-2126
Author(s):  
Steven M. Martinaitis ◽  
Benjamin Albright ◽  
Jonathan J. Gourley ◽  
Sarah Perfater ◽  
Tiffany Meyer ◽  
...  
Keyword(s):  
West Virginia ◽  
Flash Flood ◽  
Weather Prediction ◽  
Time Frame ◽  
Flash Floods ◽  
Hydrologic Model ◽  
Probability Of Detection ◽  
Flood Event ◽  
Flash Flooding ◽  
Testbed Experiments

AbstractThe flash flood event of 23 June 2016 devastated portions of West Virginia and west-central Virginia, resulting in 23 fatalities and 5 new record river crests. The flash flooding was part of a multiday event that was classified as a billion-dollar disaster. The 23 June 2016 event occurred during real-time operations by two Hydrometeorology Testbed (HMT) experiments. The Flash Flood and Intense Rainfall (FFaIR) experiment focused on the 6–24-h forecast through the utilization of experimental high-resolution deterministic and ensemble numerical weather prediction and hydrologic model guidance. The HMT Multi-Radar Multi-Sensor Hydro (HMT-Hydro) experiment concentrated on the 0–6-h time frame for the prediction and warning of flash floods primarily through the experimental Flooded Locations and Simulated Hydrographs product suite. This study describes the various model guidance, applications, and evaluations from both testbed experiments during the 23 June 2016 flash flood event. Various model outputs provided a significant precipitation signal that increased the confidence of FFaIR experiment participants to issue a high risk for flash flooding for the region between 1800 UTC 23 June and 0000 UTC 24 June. Experimental flash flood warnings issued during the HMT-Hydro experiment for this event improved the probability of detection and resulted in a 63.8% increase in lead time to 84.2 min. Isolated flash floods in Kentucky demonstrated the potential to reduce the warned area. Participants characterized how different model guidance and analysis products influenced the decision-making process and how the experimental products can help shape future national and local flash flood operations.

scholarly journals An early warning system for flash floods in hyper-arid Egypt

2012 ◽  
Vol 12 (2) ◽  
pp. 443-457 ◽  
Author(s):  
J. Cools ◽  
P. Vanderkimpen ◽  
G. El Afandi ◽  
A. Abdelkhalek ◽  
S. Fockedey ◽  
...  
Keyword(s):  
Early Warning ◽  
Early Warning System ◽  
Flash Flood ◽  
Temporal Distribution ◽  
Warning System ◽  
Field Measurements ◽  
Flash Floods ◽  
Data Availability ◽  
Flood Events ◽  
Emergency Procedures

Abstract. An early warning system (EWS) for flash floods has been developed for part of the Sinai peninsula of Egypt, an hyper-arid area confronted with limited availability of field data, limited understanding of the response of the wadi to rainfall, and a lack of correspondence between rainfall data and observed flash flood events. This paper shows that an EWS is not a "mission impossible" when confronted with large technical and scientific uncertainties and limited data availability. Firstly, the EWS has been developed and tested based on the best available information, this being quantitative data (field measurements, simulations and remote sensing images) complemented with qualitative "expert opinion" and local stakeholders' knowledge. Secondly, a set of essential parameters has been identified to be estimated or measured under data-poor conditions. These are: (1) an inventory of past significant rainfall and flash flood events, (2) the spatial and temporal distribution of the rainfall events and (3) transmission and infiltration losses and (4) thresholds for issuing warnings. Over a period of 30 yr (1979–2010), only 20 significant rain events have been measured. Nine of these resulted in a flash flood. Five flash floods were caused by regional storms and four by local convective storms. The results for the 2010 flash flood show that 90% of the total rainfall volume was lost to infiltration and transmission losses. Finally, it is discussed that the effectiveness of an EWS is only partially determined by technological performance. A strong institutional capacity is equally important, especially skilled staff to operate and maintain the system and clear communication pathways and emergency procedures in case of an upcoming disaster.

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