2025 Volume 81 Issue 16 Article ID: 24-16021
The purpose of this study is to classify open levee structures and evaluate the flood control function and its enhancement. This study firstly classified the shape and geological structures of all open levees existed in Class A river system. Secondly, numerical simulations were conducted by changing the riverbed gradient, the ground gradient, the angle of the second levees, the width of the unbanked section and the ground elevation determined from the existing range of the parameters. Finally, the effectiveness of an overflowing levee at the unbanked section was simulated. From the simulated maximum water levels at the downstream of the open levee, the decrease in the maximum water levels were demonstrated by the open levee and overflowing levee. Due to delay in the timing of the start of flood storage by the overflowing levee, the maximum water levels at the downstream of the open levee becomes lower than that without overflowing levee. In addition, overflowing levee reduces the inundated area in between the river levee and secondary levee. Therefore, rather than closing the open levee, construction of the overflowing levee at the unbanked section is expected to improve flood control safety at the downstream river and in the open levee area where flood inundation occurs on occasion.
