Experimental research on the jacking effect of compound flooding in a coastal city: case study in the Meishe River basin, Haikou City

The compound flood disasters driven by rainstorm, river flood, high tide level and other factors pose a serious threat to the sustainable development of coastal cities. In order to explore the jacking effect mechanism under multiple disaster causing factors, this study takes the area of Meishe River basin in Haikou City as an example, a compound flooding physical model is constructed, and the particle tracing method is employed to explore the characteristics of jacking effect in urban underground pipe network under different scenarios of rainstorm, river flood and high tide level. The research results indicate that as rainfall increases, the jacking effect on the pipeline network decrease. As the river level increases, the jacking effect increases, and the jacking effect on the pipe network extends from the river drainage outlet to the inside, the maximum length of jacking effect reaches 14.55m, with a maximum range of jacking effect by 82.58%. But as the tide level increases, the duration and range of jacking effect decrease. Under the 20-year return period rainfall, the duration of jacking effect decreases by 37 minutes, and the proportion of maximum jacking effect range decreases by 35.70%; Under the 50-year return period rainfall, the duration of jacking effect decreases by 42 minutes, and the proportion of maximum jacking effect range decreases by 30.66%. The research results can provide scientific basis for flood control and drainage engineering in coastal cities, as well as for the prevention and control of composite disasters.