Hydrologic alteration under hydropower dam operations and potential climate change : a case study in the Sesan River Basin, lower Mekong Region | |
| Author | Ghalley, Wangmo |
| Call Number | AIT Thesis no.WM-23-14 |
| Subject(s) | Climatic changes--Mekong Region--Sesan River Basin Dams--Environmental aspects--Mekong Region--Sesan River Basin Water resources development |
| 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 | Hydropower dam developments exacerbated by climate change can significantly disrupt the natural flow regimes, leading to adverse effects on river ecosystems. The Sesan River is renowned for its diverse biomes and is an important resource for nearby inhabitants. Rapid expansion of hydropower dams has occurred in recent years, but the hydrologic impacts remain poorly understood, particularly when combined with the impacts of climate change. Therefore, this study assessed the hydrologic alterations in the Sesan River due to the operation of hydropower dams and projected climate change. Daily streamflow was simulated using HEC-HMS, which was calibrated and evaluated based on streamflow observations. Climate change projections were based on daily precipitation and temperature, which were estimated using three Earth System Models (ESMs) under two Socioeconomic Pathways: SSP2-4.5 and SSP5-8.5. Future climate projections spanned 2025 to 2100, which was divided into three 25-year periods, and compared to a 30-year baseline period from 1984 to 2014. Results show a consistent rise in both precipitation and temperature for the basin across all future periods and SSP scenarios. Precipitation is expected to increase from near to far future by 4-13% for SSP2-4.5 and 7-29% for SSP5-8.5. Minimum temperature is expected to rise by 8-16% and 10-26%, and maximum temperature is expected to rise by 3-7% and 3-12% for SSP2-4.5 and SSP5-8.5, respectively. Hydrologic alterations were assessed using the Indicators of Hydrologic Alteration (IHA). The dams significantly smoothed the peaks and troughs of hydrographs. The overall alteration due to dams fell within the “moderate” category. Climate change increased the high flow rates, with the impact limited to September in the near future but impacting much of the year in the mid and far future periods. Another notable change was the shift in the peak flow timing from August in baseline to September in the future. The overall hydrologic alteration due to climate change fell within the “low” category. Finally, for the combined impact of dams and climate change, dams were found to mitigate some impacts of climate change by smoothing extreme high flows, especially in the far future period. Overall, the combined impact showed greater alteration than the individual scenarios but fell within the “moderate” category. |
| Year | 2023 |
| Type | Thesis |
| School | School of Engineering and Technology |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Water Engineering and Management (WM) |
| Chairperson(s) | Shrestha, Sangam;Niemann, Jeffrey D. (Co-Chairperson); |
| Examination Committee(s) | Ettema, Robert;Shanmugam, Mohana Sundaram;Ho Huu Loc; |
| Scholarship Donor(s) | Asian Institute of Technology Scholarship; |
| Degree | Thesis (M. Eng.) - Asian Institute of Technology, 2023 |