Development of a Low-Cost Flood-Resilient Drainage System for Urban Cities

Thesis Abstract

Urban flooding poses acute resilience and serviceability challenges in rapidly growing cities with constrained budgets, where conventional high-capital drainage solutions are often infeasible. This study addresses the gap between flood risk exposure and affordable, scalable drainage interventions by designing and evaluating a low-cost flood-resilient drainage system tailored to urban contexts with limited financial and technical resources. The aim is to develop a modular, community-implementable drainage framework that reduces peak discharge, mitigates temporary inundation, and enhances post-event rapid recovery. Specific objectives are (i) to identify urban hydrological regimes and failure modes of existing drainage networks in representative cities; (ii) to conceptualize a low-cost, modular drainage system incorporating bioswale-inspired filtration, permeable pavements, micro-catchments, and autonomous gate controls; (iii) to optimize system configuration using hydrological modeling and cost-benefit assessment; (iv) to pilot the design in controlled field trials and a representative urban district, and (v) to develop guidelines for adoption, operation, and maintenance in low-resource settings. The methodology adopts a mixed-methods, design-implementation-evaluation framework underpinned by the socio-hydrological theory of coupled human-natural systems and the resilience-infrastructure paradigm. The research design combines quantitative hydrological simulation with qualitative stakeholder engagement. The population encompasses urban drainage networks, users, and maintenance agencies in three mid-sized cities with comparable rainfall intensities and urban densities. A stratified random sampling approach selects 12 municipal districts for simulation-based evaluation and 4 districts for field piloting, with a total sample of 480 household surveys, 60 key stakeholder interviews, and 20 in-situ performance monitoring sites. Data collection instruments include (i) rainfall-runoff time series data and network flow measurements; (ii) topographic and land-use maps; (iii) sensor arrays for water level, flow velocity, and pollutant concentrations; (iv) structured questionnaires and semi-structured interview guides; and (v) maintenance cost logs. Validity and reliability are ensured through triangulation, pilot testing of instruments (n=30), back-translation for survey items, and inter-rater reliability checks for field observations. Analytical techniques comprise (i) hydrological modeling using SWMM and HEC-HMS to simulate proposed modular components under design storms and climate variability scenarios; (ii) multi-criteria decision analysis (MCDA) to compare configurations on performance, cost, and social acceptability; (iii) regression analysis to identify determinants of drainage performance and community adoption; (iv) ANOVA to test differences in peak discharge reductions across configurations and rainfall intensities; (v) life-cycle cost analysis (LCCA) to evaluate long-term economic benefits; (vi) thematic analysis of interview transcripts to capture governance, maintenance, and user perceptions; and (vii) sensitivity analysis to assess robustness under parameter uncertainty. A preliminary engineering model will specify hydraulic continuity, storage volumes, treatment performance, and control response times. Expected findings indicate that a modular system integrating bioswale-like filtration, permeable pavement, micro-catchment basins, and autonomous gate valves can reduce peak runoff by 20–35% under design storms, while delivering significant reductions in surface inundation duration in low-to-moderate rainfall events. The proposed solution is anticipated to yield a favorable benefit-cost ratio, with payback periods within 5–12 years in urban districts, and substantial non-monetary benefits including improved groundwater recharge, pollutant attenuation, and enhanced community resilience. The study contributes to knowledge by (i) operationalizing an affordable, adaptable drainage paradigm suitable for resource-constrained urban areas; (ii) advancing integration of hydrological performance with social adoption metrics in resilience planning; (iii) providing a transferable design framework and piloting methodology for other cities facing similar constraints; and (iv) delivering policy-ready guidelines for governance, maintenance regimes, and scalable deployment. The main conclusion is that low-cost, modular drainage systems can deliver measurable flood resilience gains in urban contexts without prohibitive capital expenditure, provided that design is informed by local hydrology, stakeholder needs, and rigorous life-cycle cost considerations. Recommendations include (i) institutionalizing community-based maintenance programs and clear responsibilites; (ii) adopting stepwise implementation with performance monitoring dashboards; (iii) integrating the modular system into broader climate-adaptive urban planning; and (iv) pursuing further research on performance under extreme events and long-term sediment and clogging dynamics.