Warning in the Clouds: Predicting Flood Threats Through Rainfall-Based Mathematical Approach in Tanjay City
Keywords:
Flood susceptibility, Computational modelling, Risk assessment, Rainfall threshold, Drainage coefficient, Mitigation planningAbstract
Flooding poses a severe and recurrent threat to communities in Tanjay City, Philippines, frequently disrupting critical infrastructure such as schools. This study developed and applied a computational model to quantitatively predict flood likelihood in six selected barangays, with particular focus on the locale of Tanjay City Science High School. Using a mathematical formula that integrates rainfall intensity (R), duration (T), and frequency (D) with key environmental parameters: soil coefficient (S), elevation (E), and drainage capacity (DR). This research calculated flood susceptibility values across seven recorded rainfall events during a one-month observational period. The formula applied was . The results demonstrated pronounced spatial disparities in flood risk. Barangay Luca consistently registered the highest flood likelihood, peaking at a value of 4.01, while the school’s barangay reached 3.35, indicating a tangible threat. The analysis confirms that floods are not caused by rainfalls alone but also depend on localized factors. Areas characterized by lower elevation, clay-rich soils with low permeability and insufficient drainage systems attributes of both Luca and the school’s barangay are inherently more prone to flooding. These findings provide empirical, data-driven validation of the flooding hazard facing Tanjay City Science High School. The study concludes that effective risk reduction requires targeted interventions prior to these specific geophysical vulnerabilities. Immediate recommendations include upgrading drainage infrastructure, implementing real-time water level monitoring, and formalizing school-specific flood preparedness protocols. This computational approach offers a replicable framework for evidence-based urban planning and prioritization of mitigation resources in flood-prone communities.
References
Abdulrazzak, M. J., et al. (2019). Flood risk assessment and management: A review of recent advances. Natural Hazards, 98(2), 1–25. 10.1080/19475705.2018.1545705
Anticipation Hub. (n.d.). Flood fact sheet – sectoral exposure. https://www.anticipation-hub.org/Documents/Briefing_Sheets_and_Fact_Sheets/Flood_EAP_-_Final.pdf
Berghuijs, W. R., Woods, R. A., & Hrachowitz, M. (2017). A precipitation shift from snow towards rain leads to a decrease in streamflow. Nature Climate Change, 7(8), 1–6. https://doi.org/10.1038/nclimate3344
Bertola, M., Viglione, A., Lun, D., Hall, J., & Blöschl, G. (2020). Flood trends in Europe: Are changes in rainfall responsible? Hydrology and Earth System Sciences, 24(2), 855–872. 10.5194/hess-24-1805-2020
Bündnis Entwicklung Hilft & Institute for International Law of Peace and Armed Conflict (IFHV). (2023). WorldRiskReport 2023 (English edition). https://weltrisikobericht.de/wp-content/uploads/2023/10/WRR_2023_english_online161023.pdf
Echendu, A. J. (2020). The impact of flooding on developing countries: Infrastructure and policy challenges. International Journal of Disaster Risk Reduction, 45, 101–112. https://doi.org/10.1080/20964129.2020.1791735
Frometta, V., & Feyen, L. (2019). Improving flood risk assessment by accounting for socio-economic vulnerability. Natural Hazards and Earth System Sciences, 19(6), 1–15. (PDF) Improving flood risk assessment by mapping socioeconomic …
GFDRR 2017 Annual Report | GFDRR. (2017). https://www.gfdrr.org/en/ar2017
Haslinger, K., Breinl, K., Pavlin, L., Pistotnik, G., Bertola, M., Olefs, M., Greilinger, M., Schöner, W., & Blöschl, G. (2025). Increasing hourly heavy rainfall in Austria reflected in flood changes. Nature, 639(667–672). https://doi.org/10.1038/s41586-025-08647-2
Haslinger, K., Schöner, W., & Blöschl, G. (2025). Changes in extreme rainfall and flood behavior under climate warming in Austria. Climate Dynamics, 64(3), 1–18. 10.1038/s41586-025-08647-2
Henao Salgado, J., & Zambrano Nájera, J. (2022). Early warning systems for flash flood risk management. Water, 14(9), 1–17. Assessing Flood Early Warning Systems for Flash Floods - Frontiers
Hussain, M., Tayyab, M., Zhang, J., Shah, A. A., Ullah, K., Mehmood, U., & Al-Shaibah, B. (2021). GIS-Based Multi-Criteria Approach for Flood Vulnerability Assessment and Mapping in District Shangla: Khyber Pakhtunkhwa, Pakistan. Sustainability, 13(6), 3126. https://doi.org/10.3390/su13063126
Hussain, S., et al. (2021). Integrated flood risk assessment approaches: A review. Journal of Flood Risk Management, 14(2), e12689. 10.1007/s43832-025-00193-2
Jha, M. K., & Yellareddy, K. (n.d.). Drainage engineering (Course content). Dept. of Agricultural and Food Engineering, Indian Institute of Technology, Kharagpur.https://agrifair.in/wp-content/uploads/2020/12/Drainage-Engineering-.pdf
Khodaei, H., Nasiri Saleh, F., Nobakht Dalir, A. et al. Future flood susceptibility mapping under climate and land use change. Sci Rep 15, 12394 (2025).https://doi.org/10.1038/s41598-025-97008-0
Kundzewicz, Z. W., Kanae, S., Seneviratne, S. I., Handmer, J., Nicholls, N., Peduzzi, P., Mechler, R., Bouwer, L. M., Arnell, N., Mach, K., Muir-Wood, R., Brakenridge, G. R., Kron, W., Benito, G., Honda, Y., Takahashi, K., & Sherstyukov, B. (2014). Flood risk and climate change: Global and regional perspectives. Hydrological Sciences Journal, 59(1), 1–28. https://doi.org/10.1080/02626667.2013.857411
Kurata, Y. B., Ong, A. K. S., Ang, R. Y. B., Angeles, J. K. F., Bornilla, B. D. C., & Fabia, J. L. P. (2023). Factors affecting flood disaster preparedness and mitigation in flood‑prone areas in the Philippines: An integration of Protection Motivation Theory and Theory of Planned Behavior. Sustainability, 15(P, 6657). https://doi.org/10.3390/su15086657
Lagmay, A. M. F. (2025). Discussion on flood-disease connections and infrastructure planning. As reported by Eco-Business.https://www.eco-business.com/news/poor-infrastructure-planning-in-the-philippines-worsens-post-flood-disease-surge-experts/
Liu, et al., (2024). Global, regional and national trends and impacts of natural floods, 1990–2022. Bulletin of the World Health Organization, 102(06), 410–420. https://doi.org/10.2471/blt.23.290243
Mahmood, S., Rahman, Au. Flash flood susceptibility modeling using geo-morphometric and hydrological approaches in Panjkora Basin, Eastern Hindu Kush, Pakistan. Environ Earth Sci 78, 43 (2019). https://doi.org/10.1007/s12665-018-8041-y
Mwakala, P. W., Kongo, V. N., & Mulia, R. (2009). Influence of antecedent rainfall on flood occurrence in urban areas. Journal of Hydrology, 376(1-2), 127–135. https://doi.org/10.1016/j.jhydrol.2009.07.021.
PAGASA. (n.d.). https://www.pagasa.dost.gov.ph/climate/climate-monitoring
Shi, X., Wu, J., & Qin, Y. (2025). Multiple linear regression flood risk assessment based on entropy weight method. Mathematical Methods in Applied and Numerical Analysis, 1(1), 1–12. https://doi.org/10.54097/tkvant81
Singh, A., Dawson, D., Trigg, M. A., Wright, N., Seymour, C., & Ferriday, L. (2023). Drainage representation in flood models: Application and analysis of capacity assessment framework. Journal of Hydrology, 622, 129718. https://doi.org/10.1016/j.jhydrol.2023.129718
Swain, S., Singha, C., & Nayak, L. (2020). Rainfall-induced flood modeling and risk assessment. Arabian Journal of Geosciences, 13(22), 1–14. https://doi.org/10.3390/ijgi9120720
Tanjay topographic map, elevation, terrain. (n.d.). Topographic Maps. https://en-ph.topographic-map.com/map-dnbs8/Tanjay/
UNDRR. (2019). Global assessment report on disaster risk reduction. United Nations Office for Disaster Risk Reduction. https://www.undrr.org
Ward, P. J., et al. (2017). Future flood risk in a changing climate and society. Earth’s Future, 5(5), 1–12.https://doi.org/10.5194/nhess-20-1069-2020
Wasko, C., & Nathan, R. (2019). Influence of changes in rainfall and soil moisture on trends in flooding. Journal of Hydrology, 575, 432–441. https://doi.org/10.1016/j.jhydrol.2019.05.054
World Meteorological Organization (WMO). (2021). Manual on flood forecasting and warning. WMO-No. 1072. https://library.wmo.int
Worthington, P. (2024, September 12). How does urban development contribute to flood risks? Medium. https://medium.com/@paul_15500/how-does-urban- development-contribute-to-flood-risks-774d9640bcd5
Youssef, A. M., et al. (2016). Flood hazard assessment using GIS and remote sensing. Geomatics, Natural Hazards and Risk, 7(1), 1–21.https://doi.org/10.1007/s12665-015-4830-8
Zamara, K. (2024, August 29). Soil permeability. https://www.tensarinternational.com/resources/articles/the-permeability-of-soils-explained
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