Photogrammetric Assessment of Urban Rainwater Catchment Systems in Cebu City, Philippines: Implications for Water Resource Optimization and Flood Mitigation

Abstract

Background: In many developed cities, freshwater scarcity and recurrent flooding are significant concerns, particularly in rapidly urbanizing areas. Cebu City, a major urban center in Cebu, Philippines, is facing similar challenges. Literature highlights the value of integrated water management systems, including rainwater harvesting (RWH), in responding to these overlapping issues.
Methods: This study examines the nuances of urban flooding in two flood‑prone locations in Cebu City, assesses the applicability of RWH as an integrated strategy to mitigate floods. Photogrammetry techniques were employed to collect spatial and ground information from satellite images and geohazard maps, facilitating the identification of flood occurrences and the estimation of potential rainwater capture volumes.
Results: Findings reveal that only a small fraction of catchment areas remains unpaved, limiting natural infiltration. Calculations show that approximately 1.45 million cubic meters of floodwater accumulate annually across the two study sites. To address this, the study suggests a large-capacity underground rainwater detention tank under the specific streets to capture runoff without disrupting urban space.
Conclusion: The results demonstrate that integrating RWH into flood control systems offers a practical and resilient approach to mitigating floods while supporting sustainable water resource management in dense urban environments.