A performance analysis of phase 1 drainage system of Boracay Island

Despite the efforts of the Philippine Tourism Authority (PTA) to address the flooding problem in Boracay Island, many parts of the island still gets flooded. An update to the Detailed Engineering Design (DED), like the implementation of Phase 1 D\u27Mall Pumping station served as a benchmark in addressing the recurrent problem on flooding in Phase 1 Boracay. However, the drainage system\u27s response under higher rainfall events is yet to be determined since the D\u27mall portion of the Phase 1 Boracay Drainage Improvement Project was only designated for a 10-year rainfall event. The frequency of flooding in Boracay is a prominent issue 1 given that within approximately 30 minutes of continuous rainfall, many areas had been observed to be flooded. The efficiency of the drainage system depends heavily on its performance under a rainfall event.This study analyzed the performance of the Phase 1 drainage system of Boracay Island. Criteria were made to assess the performance of the system. The DED and rainfall data from PTA were used to simulate the existing situation while the software, Storm Water Management Model (SWMM) version 5.1, was used to simulate flow of rainwater throughout the system. The analysis was done by integrating the existing condition, simulated flow of rainwater for a rain event, and set criteria.A validated flood model showed that behavior of the drainage system under a 25-year and 50-year rain event cannot be accommodated by the system. Some parts of the system became pressurized before reaching the maximum capacity of the pump and retention reservoir. The analysis of the drainage system validated the performance of the drainage system under the said rain events. With the assessed performance, the study can be useful to review the drainage system\u27s performance and reliability, and can also provide areas for improvement for the local government to help address the flooding problem of Phase 1 in Barangay Balabag, Boracay Island, in the municipality of Malay, Aklan province