Risk Analysis of Power Supply in San Juan, Surigao City, Philippines Due to Extreme Floods

Abstract

The power supply system and its network components, like any other lifeline, are at risk due to extreme floods. Although various adaptive measures by the power producer can reduce this risk, the infrastructure (demand side) connected to the substation are still at risk to extreme inundation primarily because of its elevation, thus rendering the adaptation measures inadequate. In this paper, the authors use geographic information technology to quantify the risk of power loss to the consumers and the ensuing economic loss to the power producer considering various extreme inundation events. These extreme flood events were based on hypothetical rainfall with return periods of 2, 5, 10, 25 and 50 years. Specifically, the authors developed a risk curve for the power supply system in barangay San Juan, Surigao City, Surigao Del Norte, Philippines. The study shows that the percentage of households vulnerable to extreme floods for each return period are 22, 91, 93, 94 and 96. This power outage translates to a potential money loss range from US$ 1800 to US$ 36,000 for the power provider. To reduce the risk the following adaptation measures can be adopted by the local government (a) improve the drainage system, (b) rehabilitate Surigao River and consider buffer zone / overflow structures, (c) proper zoning and relocation of flood residents to elevated areas and (d) install new transformers to isolate households that are frequently flooded so power outage is reduced during extreme events.