Hydrological and hydraulic modeling of concrete fuse plug operation for small dams

Introduction
Concrete fuse plugs are a new technology used to increase storage capacity and spillway discharge at a low cost. The fuse plugs consist of simple, large concrete blocks installed side-by-side in the spillway. They are stable until the water in the reservoir reaches a certain level over them, at which point the blocks are designed to tilt and be ejected to increase discharge. In a context of changing climate, these solutions can be particularly useful to adapt existing infrastructure to varying hydrology or changing water demand. This project aimed to review the use and design of concrete fuse plugs, as well as develop a methodology to model the river floods caused by the operation of the fuse plug. This methodology was then tested using as a case study the Yacouta dam, located in the Sahel region of Burkina Faso.

Project Aim and Objectives
The project aims to identify methods of developing a computerized, geo-referenced hydraulic model which will simulate the behavior of concrete fuse plugs on small dams and assess flooding downstream of the structure. More specifically, the research objectives are to: review existing literature on concrete fuse plug technologies and design a concrete fuse plugs installation in the context of the Yacouta dam; identify low-cost hydraulic model development and calibration methodologies which can be adapted for concrete fuse plugs; develop and calibrate a hydraulic model of the Yacouta dam with different scenarios to evaluate downstream flooding impacts; and prepare a set of recommendations and guidelines which can be used to replicate the modeling process for other dams. As flood events change in frequency and intensity, it will be key to have appropriate methodologies to assess their impacts in a perspective of climate change adaptation.

Methodology
The methodology devised to conduct the research was formulated based on literature review findings. As such, elements regarding the use of the concrete fuse plugs were further investigated so that the device could be sized in the context of the case study. Hydraulic modeling was then conducted using a combination of existing methodologies to assess if they could effectively be replicated using free software options such as QGIS for geospatial processing, RiverGIS for model building and in HEC-RAS for 2D flood modeling.