Forecasting and Providing Warnings of Flash Floods for Ungauged Mountainous Areas Based on a Distributed Hydrological Model

Abstract

Flash floods occur in mountainous catchments with short response times, which are among the most devastating natural hazards in China. This paper intends to forecast and provide warnings of flash floods timely and precisely using the flash flood warning system, which is established by a new distributed hydrological model (the China flash flood hydrological model, CNFF-HM). Two ungauged mountainous regions, Shunchang and Zherong, are chosen as the study areas. The CNFF-HM is calibrated in five well-monitored catchments. The parameters for the ungauged regions are estimated by regionalization. River water stage data and reservoir water stage data from Shunchang, and reservoir water stage data from Zherong are used to validate the model. The model performs well and the average Nash-Sutcliffe efficiency (NSE) is above 0.8 for the five catchments. The validation shows the difference in the timing of flood peaks using the two types of water stage data is less than 1 h. The rising and declining trends of the floods correspond to the observed trends over the entire validation process. Furthermore, the flash flood warning system was effectively applied in flash flood event on 28 September 2016 in Zherong. Thus, the CNFF-HM with regionalization is effective in forecasting flash floods for ungauged mountainous regions.

Assessment of Flood Inundation by Coupled 1D/2D Hydrodynamic Modeling: A Case Study in Mountainous Watersheds along the Coast of Southeast China

“…Throughout the relevant theories, technologies and practices of mountain torrents prevention all over the world, the understanding of triggering factors and formation mechanism of mountain torrents is still at a relatively macro level and partial qualitative level [11][12][13]. In recent years, systematic research on the formation and disaster-causing dynamics of flash floods in small watersheds, and research on the dynamic characteristics of flash floods [14] and simulation methods and technologies [15] have received widespread attention. In the southeastern coastal watershed in particular, while retaining the natural characteristics of mountainous areas, the rapid economic development in the middle and lower reaches, the accumulation of wealth and the population has magnified the flood risk.…”

Precipitation Forecast Contribution Assessment in the Coupled Meteo-Hydrological Models

“…The safety of lives and properties is always threatened by the severe floods. Meteo-hydrological predictions are important for providing early flood warnings and preventing or reducing flood damages [2,3]. The high resolution Numerical Weather Prediction (NWP) models provided notable improvement in Quantitative Precipitation Forecast (QPF).…”

Gridded Flash Flood Risk Index Coupling Statistical Approaches and TOPLATS Land Surface Model for Mountainous Areas

“…Most of those catastrophes have occurred in ungauged mountainous areas, but methods for classifying the flash flood risk index (FFRI) in ungauged mountainous areas remain few. There is some previous literature forecasting and providing warnings of flash floods for ungauged mountainous areas based on a distributed hydrological model [2][3][4][5][6][7][8]. For example, Reed et al [2] studied flash flood forecasting at ungauged locations with a distributed hydrologic model and threshold frequency-based method.…”

“…For example, Reed et al [2] studied flash flood forecasting at ungauged locations with a distributed hydrologic model and threshold frequency-based method. Wang et al [3] established a flash flood warning system based on a distributed hydrological model applied to two ungauged mountainous regions.…”