Assessment of climate change impacts on river hydrology and morphology and resulting socio-economic vulnerability : a case study of the Chindwin river basin in Myanmar
- Pathum Thani, Thailand : Asian Institute of Technology, 2018
- 1 online resource, 139 leaves : ill.
- Thesis ; no. WM-18-01 .
- Asian Institute of Technology. Thesis ; no. WM-18-01 .
A thesissubmitted in partial fulfillment of the requirements for the degree of Master ofEngineering in Water Engineering and Management
Thesis (M. Eng.) - Asian Institute of Technology, 2018
This study assessedthe near future climate change, its impact on basin hydrology and river morphological changes, and the resulting socio-economic vulnerability of the riverine communitiesin 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 morphologymodel using MIKE 21 Flow Model FM were developed for the impact assessment. The vulnerability assessment was anindicator-basedassessment, 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 floodby 8-10 days.Furthermore, the mean and maximum discharge is projected to increaseduringthe Hot and Dry Season and Wet season inthe nearfuture. Most importantly in a morphodynamic point of view, the extreme flood events are expected to get more severe in future interms of frequency and magnitude. The calibrated morphology model which was used to simulate four extremeeventspredictinghighsedimentdeposition atnarrow locationsand downstream of them,as the flood recedes.Thismay cause channel migration andbraiding due to completeriver 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 highflows will be amplified due to climate change in near future, morphologychanges will beexacerbated in the same period.Sediment deposition will increase the flood risk and river bank instability, constrainingnavigability in the riverand adversely affectingriverine communities.The results revealed that the river morphology changes are mainly due to high flowevent suggesting that simulation of such eventsis adequate enough to study morphodynamic changes allowing to avoid many issuesassociated with long duration 2D hydrodynamic simulations.Thesocio-economic vulnerability assessment conducted under this study identified the riverine community of Yesagyo andChaung U respectively as the most and leastvulnerable out of three townships assessed. This was attributed to high sensitivity and exposure to morphology related changesin 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.
Climatic changes--Myanmar--Chindwin River Basin Hydrology--Myanmar--Chindwin River Basin