A Conceptual Framework for Integrated Rehabilitation of Urban Sewer Networks Under Flood Risk Conditions

Abstract

Aim: The objective of this study is to develop an integrated rehabilitative framework for urban sewer systems (USS). The study addresses the systemic weaknesses associated with aging sewer systems in major cities, which can contribute to sewer overflows, urban flooding, environmental degradation, service disruptions, and economic losses. Methods: The study employs advanced hydraulic modeling, vulnerability assessment methods, sensor-based monitoring, multi-criteria decision analysis (MCDA), and resilience evaluation. These approaches are used to prioritize rehabilitative interventions and optimize resource allocation for municipalities. Simulation was used to assess overflow occurrences and network resilience, while cost-benefit analysis was used to evaluate the economic viability of the rehabilitation strategy. Results: The simulation identified up to 10 critical nodes causing overflows each year in the high-risk area. Following rehabilitation, the number of critical nodes was reduced from 18 to 11. Network resilience also showed a positive trend, with operational redundancy increasing to 40% and the time required to resolve an outage decreasing from 8 hours to less than 4 hours. The cost-benefit analysis found the rehabilitation strategy to be economically viable, assuming a 30% reduction in flood damage, equivalent to £7.5 million in flood damage avoided per annum. Conclusion: The results emphasize the need for data-driven, system-wide rehabilitation strategies to support urban infrastructure planning and flood risk reduction. Such strategies can increase network resilience, protect public welfare, and promote sustainable water use in cities. Recommendation: Implementation should involve coordinated investments in integrated monitoring systems, predictive maintenance, and standardized risk-assessment procedures, together with long-term institutional capacity-building to support implementation.