Pluvial flood hazard assessment and management under urbanization and climate change scenarios in Kathmandu Metropolitan City, Nepal | |
| Author | K. C., Saurav |
| Call Number | AIT Thesis no.WM-19-08 |
| Subject(s) | Flood control--Nepal--Kathmandu Urbanization--Nepal--Kathmandu Climatic changes--Nepal--Kathmandu |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Water Engineering and Management |
| Publisher | Asian Institute of Technology |
| Abstract | Urbanization and climate change collectively impose threats for pluvial flooding in cities. The transformation of natural landcover toward imperviousness and the changes in local climatic condition, increases flood frequencies in rapidly growing metropolitans like Kathmandu. This study emphases to assess the impact of urbanization and climate change in pluvial flooding of Kathmandu Metropolitan City (KMC), Nepal. The study used observed rainfall data, three individual RCMs namely ACCESS 1, CNRM and MPI and one ENSEMBLE RCM (average) to analyze the historical and future rainfall trend and extreme analysis. The overall results showed that KMC is likely to have more intense rainfall events with shorter durations in the future. Moreover, the performance of ensembled RCM after linear bias correction shows an underestimation for extreme events as compared to individual RCMs. The study deals with the individual and combined impact of urbanization and climate change using PCSWMM Professional 2D model and the results show that, KMC is likely to have increase in flood volume, extent, depth and velocity. CNRM (2 and 20-year return period) under RCP 4.5 projects the maximum flooding in future. The increase in flood volume for current and extreme imperviousness under different climate change scenarios is likely to be more than 60% exceeding up to 90% as compared to the baseline conditions. For a 2-year return period, KMC is likely to increase in flooding extent with average maximum depth 0.10-0.25 m (low- medium hazard depths). Similarly, the flooding velocity is likely to increase in the areas with a depth greater than 0.25-0.4 m (and higher). In case of the 20-year return period, KMC is likely to have more increase in flooding areas having depth between 0.25-0.4m followed by areas with depth more than 0.4m. The four major cause of frequent pluvial flooding in KMC are increased impervious cover, unplanned settlement, clogging of sewers and undersized design of sewers. The study analyzed that reducing the surface runoff through infiltration and introducing overflow storages can reduce flood by 20-35%. Furthermore, there is a great need for exploring location-based effective adaptation and/or management options to reduce the frequent pluvial flood in KMC. |
| Year | 2019 |
| Type | Thesis |
| School | School of Engineering and Technology (SET) |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Water Engineering and Management (WM) |
| Chairperson(s) | Sangam Shrestha; |
| Examination Committee(s) | Tawatchai Tingsanchali;Sarawut Ninsawat;Somchai Chonwattana; |
| Scholarship Donor(s) | Asian Institute of Technology Fellowship; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2019 |