Investigating the Optimum Pattern of Levee System Fuse Plugs by a Two-Dimensional Model

Abstract

The objective of the present research is to provide a more comprehensive hydraulic analysis of flow pattern around emergency spillways of the levee systems and also recommend an optimum pattern for installation of fuse plug spillways. The design of fuse plug spillways is usually based on very simple assumptions or 1-D models which neglect the influence of flow pattern around a fuse plug spillway on the neighboring spillways. These assumptions may lead to improper design of a set of emergency spillways. Application of 2-D models is highly recommended for the assessment of those effects. In this study, MIKE21 is used as a 2-D model to study the flow pattern around a set of fuse plug spillways. MIKE21 model is based on numerical solution of 2-D depth averaged Navier-Stokes equations. The modeling results are used to recommend the optimum pattern of fuse plug spillways. The results also show that installation of separate spillways decrease the total outflow about 1.01% to 1.35% compared to single a spillway. As a case study, Helleh River in Iran was considered. Several patterns for fuse plugs were modeled and the optimum pattern was selected based on economic and technical criteria. The influence of the flow patterns around each spillway on the neighboring spillways and the flood propagation on dry bed in the flood plain are presented as graphs and animations. The results of this study demonstrate the performance of MIKE21 for these types of the modeling and also may be helpful for designers of the flood protection levees in similar cases.