Abstract
Mountain flood disasters in China’s southeastern coastal watershed are not predictable and are sudden. With rapid urbanization and development in the middle and lower reaches of the region, the accumulation of wealth and population has magnified the flood risk. Exploring flood numerical simulation technology suitable for the rapid economic development of mountainous basins, effective flood models are the key tools for controlling and mitigating flood disasters. In this paper, we established a 1D/2D real-time dynamic coupling hydraulic model, aimed at exploring the applicability of the model in flood simulation of mountainous river basins with rapid economic development. The Luojiang River Basin (Huazhou Section) in Guangdong Province was used as the case study. The model’s ability was validated against the 22 July 2010 and 14 August 2013 inundation events that occurred there. The simulation results show that the output of the flood model is highly similar to the observation and survey results of historical flood events. The research results prove that the 1D/2D coupling model is not only an applicable tool for exploring flood spread characteristics such as flood range, velocity, depth, arrival time, and duration, but also can feed back the impact of water conservancy projects such as dikes on flood spread in the basin. It is of great significance to effectively guide the comprehensive design and management of subsequent wading projects in mountain river basins, and to improve flood prevention and disaster reduction capabilities in mountain areas.
Highlights
Mountain torrent disasters refer to the flood disasters caused by rainfall in hilly areas and the debris flows and landslides caused by mountain torrents, which cause losses to the national economy and people’s lives and property [1,2,3]
“China Bulletin on Flood and Drought Disasters 2017”, the proportion of deaths caused by mountain torrents in China exceeded 50% of the total deaths caused by floods in 1991–2017, and the proportion has increased significantly since 1998 (Figure 1)
Because of the fragility of embankment works in the study area, the investigation results of past historical floods show that the main pattern of the dike failure of the Luojiang River is often caused by floods over the top of the dike, in addition to the dike’s collapse . . . , and the flood overtopping situation is more common and the loss caused by flood is much greater than that caused by simple breach
Summary
Mountain torrent disasters refer to the flood disasters caused by rainfall in hilly areas and the debris flows and landslides caused by mountain torrents, which cause losses to the national economy and people’s lives and property [1,2,3]. Aiming at the rapid development of mountain-type basins in the economy, mature and effective flood numerical simulation technology is explored Studying this issue can improve hydrological theory, and provide the necessary basis and support for detailed warnings of mountain flood disaster risks. These models are computationally efficient and flexible to set up but are subjected to modeling limitations, such as the inability to simulate flood wave lateral diffusion This is because during the mountain flood disaster, due to the complex topography of the mountainous area, the river water level rises sharply, which can cause the river embankment to break and overflow. In this formula, x, y, z: Cartesian coordinate system in space; η: water level; h: still water depth; u, v are the average value of component of velocity in x, y directions respectively; Pa : local atmospheric pressure; ρ: water density; ρ0 : reference water density; f : Coriolis parameter; Sxx, Sxy, S yx, S yy : radiation stress component; Txx, Txy, T yx, T yy : horizontal viscous stress; τsx, τsy, τbx, τby are components of flow shear stress in x, y directions at the boundary between water surface and riverbed respectively; S: source sink item; us, vs : source-sink flow velocity [29]
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