scholarly journals Evaluating flash-flood warnings at ungauged locations using post-event surveys: a case study with the AIGA warning system

2014 ◽  
Vol 59 (7) ◽  
pp. 1390-1402 ◽  
Author(s):  
Pierre Javelle ◽  
Julie Demargne ◽  
Dimitri Defrance ◽  
Jean Pansu ◽  
Patrick Arnaud
Water ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1571 ◽  
Author(s):  
Song ◽  
Park ◽  
Lee ◽  
Park ◽  
Song

The runoff from heavy rainfall reaches urban streams quickly, causing them to rise rapidly. It is therefore of great importance to provide sufficient lead time for evacuation planning and decision making. An efficient flood forecasting and warning method is crucial for ensuring adequate lead time. With this objective, this paper proposes an analysis method for a flood forecasting and warning system, and establishes the criteria for issuing urban-stream flash flood warnings based on the amount of rainfall to allow sufficient lead time. The proposed methodology is a nonstructural approach to flood prediction and risk reduction. It considers water level fluctuations during a rainfall event and estimates the upstream (alert point) and downstream (confluence) water levels for water level analysis based on the rainfall intensity and duration. We also investigate the rainfall/runoff and flow rate/water level relationships using the Hydrologic Engineering Center’s Hydrologic Modeling System (HEC-HMS) and the HEC’s River Analysis System (HEC-RAS) models, respectively, and estimate the rainfall threshold for issuing flash flood warnings depending on the backwater state based on actual watershed conditions. We present a methodology for issuing flash flood warnings at a critical point by considering the effects of fluctuations in various backwater conditions in real time, which will provide practical support for decision making by disaster protection workers. The results are compared with real-time water level observations of the Dorim Stream. Finally, we verify the validity of the flash flood warning criteria by comparing the predicted values with the observed values and performing validity analysis.


2015 ◽  
Vol 520 ◽  
pp. 367-378 ◽  
Author(s):  
Tsun-Hua Yang ◽  
Sheng-Chi Yang ◽  
Jui-Yi Ho ◽  
Gwo-Fong Lin ◽  
Gong-Do Hwang ◽  
...  

2021 ◽  
Vol 3 (1) ◽  
pp. 12-25
Author(s):  
Khagendra Raj Poudel ◽  
Ramesh Hamal

The Himalayan mountain ranges have been commonly known as one of the most vulnerable places on earth for natural hazards like landslides and flash floods. A catastrophic flash flood was witnessed in the Seti River on 5 May 2012, which exemplified how destructive it can be not just for the physical and economical loss, but also it was the loss of environment and cultural heritage sites. This paper aims to assess the flash flood event for future implications. The field study was conducted aftermath of the event, where interviews were conducted with the victims' families. It also reviewed the studies conducted by various research groups regarding this disaster. It revealed that the result of mass failure from the Annapurna IV created a temporary dam, and the sudden burst of collected water resulted in the flash flood. Overall, it took 72 lives and huge destruction of physical properties like houses, bridges, vehicles and agricultural land. The existing settlements around the Seti basin are at high risk, where it is highlighted that the concerned authority should take initiatives to minimize the possible impact by promoting awareness, installing an early warning system and building better community-based preparedness.


Water ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1061
Author(s):  
Thanh Thi Luong ◽  
Judith Pöschmann ◽  
Rico Kronenberg ◽  
Christian Bernhofer

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.


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