Subsurface analysis of the drainage system in Sampaloc District, Manila City

• Main Authors: Madrazo, Francis John R., Santos, Carl Andrew M.
• Format: text
• Language: English
• Published: Animo Repository 2010
• Subjects: Diversion structures (Hydraulic engineering) > Philippines > Metro Manila; Flood control channels > Philippines > Metro Manila; Floods > Philippines > Metro Manila; Flood control > Philippines > Metro Manila; Civil Engineering; Hydraulic Engineering
• Online Access: https://animorepository.dlsu.edu.ph/etd_bachelors/5424
• Institution: De La Salle University

Flooding has always posed a great risk to people and to property in urban areas, exposing them to frequent flooding and increasing flood depths. Sampaloc District is a low lying area an elevation as low as 1.6m above mean sea level. Metro Manila Development Authority (MMDA) flood watch report reveal that flood depths in the area since 2002-2008 ranged from 15cm to 60cm.This study looks into the flooding by checking the adequacy of the piping system with varying rainfall patterns under an assumed land cover and under scenarios with partial deposition and no deposition. Using the Storm Water Management Model (SWMM), simulations reveal that the under "no deposition" (scenario 1), flooding already occurs even with a 2-year return period rainfall covering a total flood volume of 92.030 million liters while the "with deposition" scenario (scenario 2), the flood volume is much greater covering a total volume of 209.010 million liters. In another test case, rainfall pattern of Ondoy (Typhoon Ketsana) based from Port Area Manila was used to check surcharging of sections and potentials for flooding. Results reveal that the hydraulic head exceeds the manhole or catch basin elevations by 1.0 meter to 1.5 meters along Espana, M.V. Delos Santos, Laonglaan, G. Forbes, Dimasalang, Earnshaw, Antipolo, Matimyas, Sobredad, Vito Cruz, and Honradez. This was validated using pictures of the flood and reported depths from the flood study of the Manila area by JICA in December, 2009."Both simulations reveal inadequacies in terms of full flow open channel condition capacities of conduits along Espana, M.V. Delos Santos, Laonglaan, G. Forbes, Dimasalang, Earnshaw, Antipolo, Matimyas, Sobredad, Vito Cruz, and Honradez, N. Reyes, Severino, Josefina, Lepanto, P. Margal and Lepanto. However, the model poorly estimates the flood depths along drainage mains receiving other flows from neighboring catch basins. The simulation only estimated the flood depths in inner areas and lateral flows prior to the drainage laterals.Although dredging is done by MMDA on a monthly basis, it only offers a short term solution. Structural remediation of the whole drainage system must be done in order to prevent flooding.