Dam Break Analysis of Earthen Dam in Goa

Dams are an integral part of the country’s economy and development. Dams are confines built over a river to store water and construct a reservoir that serves various purposes. It is very important to have dam safety maintenance and monitoring. Therefore, dam breach analysis becomes an essential part of examining unforeseen repercussions posed to human habitat and environment by an abrupt release of water downstream of a dam. Every dam structure needs to be assessed whether built or proposed for the risk of collapse in essence to find out the precise consequences that would arise after the breach. The present study aims to find out the breach magnitudes of the Salaulim Dam located in the Sanguem taluka in Goa using the Hydrologic Engineering Centre’s River Analysis System viz. HEC-RAS software. The dam is analyzed for the Probable maximum flood (Overtopping) scenario and the Clear Day Failure (Piping and internal erosion) failure scenario adopting the two-dimensional unsteady flow modeling. In the study, dam failures were simulated, and the average breach width, height, and side slope for the overtopping failure were 182 m, 30 m, and 1 respectively. The piping failure measured 0.7 degrees on the side, 28 meters high, and 143 meters wide. The highest velocity of the piping failure was 5.01 m/s, whereas the overtopping failure was 5.53 m/s. After the collapse, the water depth was found to be 21.12 meters and 13.17 meters, for overtopping and piping failures respectively. The peak discharge was 16002.502 m²/s for overtopping while 18925.85 m²/s for piping failure. These collapses would cause a tremendous amount of flood inundation in the downstream area. In addition to posing a risk to public health and safety, the floods would seriously affect infrastructure, livelihoods, and the environment. They would also cause property damage and interruptions to transportation.