Date of Publication

7-2025

Document Type

Bachelor's Thesis

Degree Name

Bachelor of Science in Medical Physics with Specialization in Medical Instrumentation

Subject Categories

Physics

College

College of Science

Department/Unit

Physics

Thesis Advisor

Edgar A. Vallar

Defense Panel Chair

Maria Cecilia Galvez

Defense Panel Member

Jazzie M. Jao
Floro Junior C. Roque

Abstract (English)

Flooding remains one of the most frequent and destructive natural disasters in the Philippines, with Typhoon Ondoy (Ketsana) in 2009 serving as a reminder of the consequences of urban flooding in cities such as Marikina. This study employed an open-source, web-based flood modeling tool—known as FastFlood—to analyze flood dynamics and identify the vulnerabilities of key infrastructures in Marikina City under different rainfall conditions. The research aims to assess flood hazards through replication of historical flooding events and mapping flood exposure across key facilities including hospitals, schools, churches, and evacuation centers. Using digital elevation models (SRTM and Copernicus), Sentinel-2 derived land cover data, and rainfall data from government and international sources, simulations were conducted for rainfall intensities of 18 mm/hr, 56 mm/hr, and 90 mm/hr over 1-, 3-, 6-, and 12-hour periods—along with year-return simulations of 5, 10, 20, 50, and 100 years using discharge data from FastFlood’s Global Flood Awareness System (GloFAS). Both uncalibrated and calibrated runs were performed, with calibration optimizing values for the Manning’s coefficient, infiltration rates, and channel settings to reflect Marikina’s urban terrain. Comparisons with Santillan et al.’s (2013) HEC-RAS model and the NOAH hazard maps confirmed that FastFlood accurately identified historically flood-prone barangays such as Concepcion Uno, Sto. Niño, Jesus Dela Peña, Industrial Valley, and Calumpang, 1 2 though peak depths were generally lower and coverage more extensive in some cases. The results showed that prolonged, high-intensity rainfall significantly increases flood depths, with areas near the Marikina River—such as Tumana Bridge—experiencing depths exceeding 7 meters. While FastFlood proved effective for rapid assessments and localized scenario analysis, limitations were noted in visual detail for discharge-driven simulations and potential overestimation in extreme year-return cases. It is recommended that FastFlood be used alongside curated local datasets and traditional hydraulic models for greater precision, with integration into broader flood forecasting and infrastructure planning efforts to improve resilience in flood-prone urban areas like Marikina.

Abstract Format

html

Abstract (Filipino)

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Abstract Format

html

Language

English

Format

Electronic

Keywords

Floods--Philippines--Marikina; Flood forecasting; Flood control--Philippines; Infrastructure (Economics)--Philippines--Marikina

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Embargo Period

8-20-2028

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Available for download on Sunday, August 20, 2028

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