Flood assessment of SSS Subdivision North Fairview

Flooding poses a great threat to the lives and property of people in affected areas, most especially those located in urbanized areas. SSS Subdivision North Fairview can be considered to be located in an urbanized area with the dense population and developed area surrounding it. During the typhoon Ondoy, flooding overwhelmed the village with the water levels ranging from 3 to 6 meters in parts of the village. The study determined the efficiency of the drainage system of SSS Subdivision using different rainfall patterns and assumed land cover. For each rainfall pattern there were two scenarios, silted and non-silted. Using Storm Water Management Model (SWMM), simulations of 2, 5 and 10-year design rainfall and actual rainfall data of Typhoon Ondoy were conducted. In the first scenario (Non-silted), it was shown that the drainage system of SSS Subdivision is adequate to handle such rainfall and there was no potential for flooding. However, during the 2nd scenario (Silted), it was shown that along the lower portions of the subdivision, there were already inadequate sections that have the potential to be flooded. The streets of Internal Audit, Accounting, Pension, Cuisia, Medical, Computer and Engineering were the most affected and had most potential to be flooded. In order to simulate the actual events experienced by the subdivision, the group used the actual rainfall data of Typhoon Ondoy under silted conditions. Simulation showed that most of the subdivision was under potential flooding and the difference between the ground elevation and hydraulic gradeline was ranging from 1-1.5 meters. This was proven with video footage during the typhoon and reports from residents in the village. Although the model isn’t accurate in determining the actual depths of the flood occurring along the streets within the subdivision it gives an idea on which areas can be potentially flooded. In conclusion, the subdivision is capable enough of handling the aforesaid design rainfalls when the pipe system is fully functional. Thus, the recommendation of the study is to constantly unclog pipes which in turn keep the system at its full capacity to withstand design rainfalls