scholarly journals Analysis of the specific water level of flood control and the threshold value of rainfall warning for small and medium rivers

2020 ◽  
Vol 383 ◽  
pp. 201-211
Author(s):  
Yuzhong Hu ◽  
Zhaoxia Wang ◽  
Bin Zhou ◽  
Shiqi Jiang
Keyword(s):  
Flood Control ◽  
Flash Flood ◽  
Threshold Value ◽  
Rainfall Threshold ◽  
Threshold Values ◽  
Study Region ◽  
Flood Warning ◽  
Variable Characteristic ◽  
Control Capability ◽  
The Relationship

Abstract. In order to fully use the newly-built hydrologic stations in small and medium rivers for flood warning and prevention, based on the technical line of the investigation and evaluation of flash flood disasters, different historical flood information of the warning river section was investigated, while the elevations of riverain houses were measured. The relationship between the stations and affected population has been established for the study region. According to integrated flood control capability of riverside residents, the characteristic water levers and rainfall threshold values were determined in this case. The results indicate that the warning and safety levels are 54.0 and 55.3 m, respectively. The analysis results show that the warning should be issued when the net rainfall intensity is 70 mm h−1 or 110 mm for 6 h condition. And considering the effectiveness of disaster avoidance, variable characteristic water levers of the hydrologic station for flood warning in different village were determined on the basis of the flood control capability of each village. The relationship between hydrologic numerical value and inundating influence was established in a one-to-n way.

scholarly journals Rainfall Threshold for Flash Flood Warning Based on Model Output of Soil Moisture: Case Study Wernersbach, Germany

Water ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1061
Author(s):  
Thanh Thi Luong ◽  
Judith Pöschmann ◽  
Rico Kronenberg ◽  
Christian Bernhofer
Keyword(s):  
Soil Moisture ◽  
Flash Flood ◽  
Rainfall Threshold ◽  
Probability Of Detection ◽  
Water Levels ◽  
Critical Success ◽  
Flood Warning ◽  
Critical Discharge ◽  
Critical Success Index

Convective rainfall can cause dangerous flash floods within less than six hours. Thus, simple approaches are required for issuing quick warnings. The flash flood guidance (FFG) approach pre-calculates rainfall levels (thresholds) potentially causing critical water levels for a specific catchment. Afterwards, only rainfall and soil moisture information are required to issue warnings. This study applied the principle of FFG to the Wernersbach Catchment (Germany) with excellent data coverage using the BROOK90 water budget model. The rainfall thresholds were determined for durations of 1 to 24 h, by running BROOK90 in “inverse” mode, identifying rainfall values for each duration that led to exceedance of critical discharge (fixed value). After calibrating the model based on its runoff, we ran it in hourly mode with four precipitation types and various levels of initial soil moisture for the period 1996–2010. The rainfall threshold curves showed a very high probability of detection (POD) of 91% for the 40 extracted flash flood events in the study period, however, the false alarm rate (FAR) of 56% and the critical success index (CSI) of 42% should be improved in further studies. The proposed adjusted FFG approach has the potential to provide reliable support in flash flood forecasting.

scholarly journals Rainfall threshold definition using an entropy decision approach and radar data

2011 ◽  
Vol 11 (7) ◽  
pp. 2061-2074 ◽  
Author(s):  
V. Montesarchio ◽  
E. Ridolfi ◽  
F. Russo ◽  
F. Napolitano
Keyword(s):  
Flash Flood ◽  
Central Italy ◽  
Radar Data ◽  
Rainfall Threshold ◽  
False Alarms ◽  
Threshold Values ◽  
Protection Measures ◽  
Loss Of Life ◽  
Critical Discharge ◽  
River Cross Section

Abstract. Flash flood events are floods characterised by a very rapid response of basins to storms, often resulting in loss of life and property damage. Due to the specific space-time scale of this type of flood, the lead time available for triggering civil protection measures is typically short. Rainfall threshold values specify the amount of precipitation for a given duration that generates a critical discharge in a given river cross section. If the threshold values are exceeded, it can produce a critical situation in river sites exposed to alluvial risk. It is therefore possible to directly compare the observed or forecasted precipitation with critical reference values, without running online real-time forecasting systems. The focus of this study is the Mignone River basin, located in Central Italy. The critical rainfall threshold values are evaluated by minimising a utility function based on the informative entropy concept and by using a simulation approach based on radar data. The study concludes with a system performance analysis, in terms of correctly issued warnings, false alarms and missed alarms.

scholarly journals Correlation between LID Flood Control Capability and Runoff Coefficient

2020 ◽  
Vol 20 (5) ◽  
pp. 339-351
Author(s):  
Yonggil Jeong ◽  
Jongpyo Park ◽  
Hyunsuk Sin
Keyword(s):  
Flood Control ◽  
Low Impact Development ◽  
Qualitative Evaluation ◽  
Development Projects ◽  
Runoff Coefficient ◽  
Evaluation Procedures ◽  
Runoff Reduction ◽  
Control Capability ◽  
The Impact ◽  
The Relationship

Short-term heavy rains caused by global warming could lead to urban flooding as well as damage to both people and property. Although Korea is taking active measures to reduce the impact of flood-related disasters through disaster impact assessments, these assessments mainly consist of qualitative evaluation procedures for urban inundation when designating districts for development projects. The recently developed “inundation determination and detention site size calculation program” has made it possible to review urban inundation hydraulic calculations, even when designating districts for development projects. However, there is still a limit to the hydraulic review and the utilization of Low Impact Development (LID) facilities due to the lack of linkage between the use of such facilities and the inundation determination program. Accordingly, it is necessary to develop a technique to utilize runoff coefficients in applying the LID in the flood determination program. Therefore, in this study, the flood control capacity of stormwater runoff reduction facilities at each LID facility was reviewed and the relationship with runoff coefficient was analyzed.

scholarly journals A Bayesian decision approach to rainfall thresholds based flood warning

2006 ◽  
Vol 10 (3) ◽  
pp. 413-426 ◽  
Author(s):  
M. L. V. Martina ◽  
E. Todini ◽  
A. Libralon
Keyword(s):  
Real Time ◽  
Initial Conditions ◽  
Flood Forecasting ◽  
Rainfall Threshold ◽  
Precipitation Forecast ◽  
Bayesian Decision ◽  
Threshold Values ◽  
Flood Warning ◽  
Critical Rainfall ◽  
Forecasting System

Abstract. Operational real time flood forecasting systems generally require a hydrological model to run in real time as well as a series of hydro-informatics tools to transform the flood forecast into relatively simple and clear messages to the decision makers involved in flood defense. The scope of this paper is to set forth the possibility of providing flood warnings at given river sections based on the direct comparison of the quantitative precipitation forecast with critical rainfall threshold values, without the need of an on-line real time forecasting system. This approach leads to an extremely simplified alert system to be used by non technical stakeholders and could also be used to supplement the traditional flood forecasting systems in case of system failures. The critical rainfall threshold values, incorporating the soil moisture initial conditions, result from statistical analyses using long hydrological time series combined with a Bayesian utility function minimization. In the paper, results of an application of the proposed methodology to the Sieve river, a tributary of the Arno river in Italy, are given to exemplify its practical applicability.

scholarly journals Rainfall Threshold for Flash Flood Warning Based on Model Output of Soil Moisture: Case Study Wernersbach, Germany

2021 ◽  
Author(s):  
Thanh Thi Luong ◽  
Judith Pöschmann ◽  
Rico Kronenberg ◽  
Christian Bernhofer
Keyword(s):  
Soil Moisture ◽  
Flash Flood ◽  
Rainfall Threshold ◽  
Probability Of Detection ◽  
Water Levels ◽  
Critical Success ◽  
Flood Warning ◽  
Critical Discharge ◽  
Available Information

Convective rainfall can cause dangerous flash floods within less than six hours. Thus, simple approaches are required for issuing quick warnings. The Flash Flood Guidance (FFG) approach pre-calculates rainfall levels (thresholds) potentially causing critical water levels for a specific catchment. Afterwards, only rainfall and soil moisture information is required to issue warn-ings. This study applied the principle of FFG to the Wernersbach Catchment (Germany) with excellent data coverage using the BROOK90 water budget model. The rainfall thresholds were determined for durations of 1 to 24 hours, by running BROOK90 in “inverse” mode, identifying rainfall values for each duration that led to exceedance of critical discharge (fixed value). After calibrating the model based on its runoff, we ran it in hourly mode with four precipitation types and various levels of initial soil moisture for the period 1996 – 2010. The rainfall threshold curves showed a very high probability of detection (POD) of 91% for the 40 extracted flash flood events in the study period, however, the false alarm rate (FAR) of 56% and the critical success index (CSI) of 42% should be improved in further studies. The approach proved potential as an early flood indicator for head-catchments with limited available information.

scholarly journals A Bayesian decision approach to rainfall thresholds based flood warning

2005 ◽  
Vol 2 (6) ◽  
pp. 2663-2706 ◽  
Author(s):  
M. L. V. Martina ◽  
E. Todini ◽  
A. Libralon
Keyword(s):  
Real Time ◽  
Initial Conditions ◽  
Flood Forecasting ◽  
Rainfall Threshold ◽  
Precipitation Forecast ◽  
Bayesian Decision ◽  
Threshold Values ◽  
Flood Warning ◽  
Critical Rainfall ◽  
Forecasting System

Abstract. Operational real time flood forecasting systems generally require a hydrological model to run in real time as well as a series of hydro-informatics tools to transform the flood forecast into relatively simple and clear messages to the decision makers involved in flood defense. The scope of this paper is to set forth the possibility of providing flood warnings at given river sections based on the direct comparison of the quantitative precipitation forecast with critical rainfall threshold values, without the need of an on-line real time forecasting system. This approach leads to an extremely simplified alert system to be used by non technical stakeholders and could also be used to supplement the traditional flood forecasting systems in case of system failures. The critical rainfall threshold values, incorporating the soil moisture initial conditions, result from statistical analyzes using long hydrological time series combined with a Bayesian utility function minimization. In the paper, results of an application of the proposed methodology to the Sieve river, a tributary of the Arno river in Italy, are given to exemplify its practical applicability.

scholarly journals Evaluating the Performance of Corner Detection Approaches for Features Extraction from UAV Images

2019 ◽  
Author(s):  
Abdulla Al-Rawabdeh ◽  
Ali Almagbile ◽  
Ahmad khawaldeh ◽  
Omar Aldayafleh ◽  
Mohammad Zeitoun ◽  
...  
Keyword(s):  
Threshold Value ◽  
Corner Detection ◽  
Threshold Values ◽  
Harris Corner ◽  
Harris Detector ◽  
Camera Position ◽  
The Common ◽  
Uav Images ◽  
The Relationship ◽  
Better Than

Many corner detector techniques have already been used in extracting information from UAV images to perform various photogrammetric and mapping activities. Among these techniques is the Feature from Accelerated Segment Test (FAST) and the Harris corner detector. It is widely agreed that the evaluation of detectors is of great importance because it evaluates and enhances the accuracy of the detected features. This research evaluates the performance of FAST-9 and FAST-12 as well as the Harris detector in terms of the repeatability rate, completeness, and correctness under different threshold values. Each method is evaluated in terms of its ability for detection UAV objects (crowd and cars features). Then the common detected features between both FAST versions and the Harris detector are extracted. This is to determine which method performs best under different image conditions (e.g., illumination variations, camera position and orientation, and image noise). The results show that the size of the threshold plays a crucial role in determining the number of detected feature points. An increase in the threshold value leads to a decrease in the number of detected points and vice versa. Thus, the correctness decreases whereas the completeness increases as a function of the threshold values. Furthermore, the relationship between the FAST-9 and the Harris detector is slightly better than those between the FAST-12 and the Harris detector. This is because the number of common features between the FAST-9 and the Harris detector are relatively higher than those between the FAST-12 and the Harris detector.

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