| Author | Imbulana, Kuruwita Arachchige Naditha Damsarani |
| Call Number | AIT Thesis no.WM-18-01 |
| Note | A thesis submitted in partial fulfillment of the requirements for the
degree of Master of Engineering in
Water Engineering and Management, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Abstract | This study assessed the near future climate change, its impact on basin hydrology and river morphological changes, and the resulting socio-economic vulnerability of the riverine communities in the Chindwin River Basin, Myanmar. The study projected the future climate using data from four Regional Climate Models (RCMs) under two Representative Concentration Pathways (RCPs) and developed an ensemble of the climate models using a performance-based weight assigning method. A hydrological model using MIKE NAM and a morphology model using MIKE 21 Flow Model FM were developed for the impact assessment. The vulnerability assessment was an indicator-based assessment, which utilized 24 indicators under the domains of exposure, economic sensitivity, physical sensitivity, social adaptive capacity and demographic adaptive capacity.
The multi-modal ensemble of climate models outperformed single RCMs in predicting future climate. Average near future rainfall is projected to increase during the wet season across the basin under both RCPs while no such clear pattern was observed for the dry season. However, the future maximum and minimum temperature is projected to increase compared to mean baseline value in more than 75% of the near future years under both RCPs.
The mean annual discharge is projected to increase by 13.9% and 22.8% respectively under RCP4.5 and RCP8.5 in near future. The annual hydrograph showed faster rising and recession of monsoon flood with multiple peaks replacing the single peak observed during the baseline, and a foreword shift of the flood by 8-10 days. Furthermore, the mean and maximum discharge is projected to increase during the Hot and Dry Season and Wet season in the near future. Most importantly in a morphodynamic point of view, the extreme flood events are expected to get more severe in future in terms of frequency and magnitude.
The calibrated morphology model which was used to simulate four extreme events predicting high sediment deposition at narrow locations and downstream of them, as the flood recedes. This may cause channel migration and braiding due to complete river closure at such sections. These effects were prominent during high flood events. The left bank of the upstream areas is projected to experience most severe morphology changes. As high flows will be amplified due to climate change in near future, morphology changes will be exacerbated in the same period. Sediment deposition will increase the flood risk and river bank instability, constraining navigability in the river and adversely affecting riverine communities. The results revealed that the river morphology changes are mainly due to high flow event suggesting that simulation of such events is adequate enough to study morphodynamic changes allowing to avoid many issues associated with long duration 2D hydrodynamic simulations.
The socio-economic vulnerability assessment conducted under this study identified the riverine community of Yesagyo and Chaung U respectively as the most and least vulnerable out of three townships assessed. This was attributed to high sensitivity and exposure to morphology related changes in Yesagyo, despite its high adaptive capacity. The results could guide decision makers to prioritize areas where immediate mitigative and adaptive measures need to be taken to sustainable face climate change driven hydrology and morphology challenges in neat future. |
| Year | 2018 |
| 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) | Shrestha, Sangam ; |
| Examination Committee(s) | Duc Hoang Nguyen;Sarawut Ninsawat;Somchai Chonwattana;Thanapon Piman ; |
| Scholarship Donor(s) | Thailand (HM King); |