Hybrid green-grey infrastructure adaptation pathways of climate-resilient flood management in data-scarce urban catchments : the case of Udon Thani City, Thailand | |
| Author | Ahmed, Fahad |
| Call Number | AIT Diss. no.WM-26-02 |
| Subject(s) | Flood control--Udon Thani--Thailand Floods--Mathematical models--Udon Thani--Thailand Multiple criteria decision making |
| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Water Engineering and Management |
| Publisher | Asian Institute of Technology |
| Abstract | Urban pluvial flooding poses a growing challenge for rapidly urbanizing cities, where climate-induced increases in rainfall intensity can exceed the capacity of conventional drainage systems. In tropical, data-scarce urban catchments, this challenge is further intensified by rapid land-use change, increasing imperviousness, and limited hydrological observations for model calibration. This study develops hybrid green–grey infrastructure adaptation pathways for climate-resilient flood management in Udon Thani City, Thailand. A high-resolution coupled 1D–2D Storm Water Management Model was established to represent interactions between the underground drainage network and surface inundation processes. Sensitivity analysis was conducted to identify key hydrological and hydraulic parameters influencing runoff generation, flood volume, peak runoff, and drainage-network exceedance. Due to the lack of observed flood records, the model was calibrated using a design-performance-based approach, with the objective of achieving no node flooding under the 5-year, 1-hour design storm. Future rainfall conditions were assessed using bias-corrected precipitation projections from nine CMIP6 general circulation models under SSP2-4.5 and SSP5-8.5. The rainfall analysis showed increasing annual rainfall, rainfall intensity, and heavy-rainfall frequency under future climate conditions, with stronger intensification of extreme rainfall toward the far future, particularly under SSP5-8.5. The calibrated 1D–2D model was then used to evaluate 425 green–grey infrastructure scenarios across multiple rainfall return periods and climate conditions. These scenarios included detention tanks, four low-impact development practices including bioretention cells, green roofs, permeable pavements, and rain gardens and their hybrid combinations. Detention tank locations were prioritized using the TOPSIS multi-criteria decision-making method. The results show that hybrid green–grey configurations consistently outperformed standalone detention or LID measures across return periods and climate scenarios. Under the 50-year return period event, the best hybrid configuration achieved 95.81– 100% reduction in flood volume, 96.24–100% reduction in flooded nodes, 55.78– 57.99% reduction in peak runoff, and 50.80–52.60% reduction in total runoff. Under the more extreme 100-year return period event, the best hybrid configuration achieved 91.91–100% reduction in flood volume, 95.37–99.09% reduction in flooded nodes, 53.34–57.83% reduction in peak runoff, and 49.56–52.32% reduction in total runoff. Flood volume and flooded nodes were the most climate-sensitive indicators, while peak runoff reduction remained constrained under extreme rainfall conditions. Total runoff reduction was comparatively stable and was mainly controlled by the extent of LID implementation. Based on these findings, adaptation pathways were developed for 50- and 100-year return period events to identify when interventions remain effective, when performance declines, and when transition to stronger hybrid measures is required. The pathways indicate that LID-dominated strategies can provide substantial benefits under moderate rainfall conditions, but integrated detention–LID configurations become essential under higher return periods and future climate stress. The study provides a transferable modelling and decision-support approach for climate-resilient flood management in rapidly urbanizing, data-scarce tropical cities. |
| Year | 2026 |
| Type | Dissertation |
| School | Faculty of Civil and Environmental Engineering (2026) |
| Department | Other Field of Studies (No Department) |
| Academic Program/FoS | Water Engineering and Management (WEM) |
| Chairperson(s) | Natthachet Tangdamrongsub;Ho, Huu Loc (Co-chairperson); |
| Examination Committee(s) | Babel, Mukand S.;Pramanik, Malay |
| Scholarship Donor(s) | MESSEA-GEDSI/NbS/SAGA-NAFOS Projects;AIT Scholarship; |
| Degree | Thesis (Ph.D.) - Asian Insitute of Technology, 2026 |
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