Impact of climate change and land use and land cover change on river health in the Songkhram Basin, Thailand | |
| Author | Baghel, Triambak |
| Call Number | AIT Diss. no.WM-24-03 |
| Subject(s) | Climatic changes--Thailand--Songkhram Basin Land use--Thailand--Songkhram Basin Land cover--Thailand--Songkhram Basin |
| 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 | Rivers are crucial components of the water cycle, contributing significantly to socio economic development, serving as channels for nutrient cycling, and being important for aquatic life. Additionally, rivers provide water for drinking, agriculture, and industrial purposes. Due to climate change (CC), the hydrological cycle is expected to alter, resulting in projected changes in the regimes of rivers. In addition to climate change, socio-economic development causes land use/land cover change (LULCC) to have additional profound effects. These alterations pose a threat to the quality, quantity, and resilience of river ecosystems, as well as the river health. However, most previous research focuses on current river health assessment, there are no such studies which have assessed CC and LULCC impact on future river health. This study aims to provide a methodological tool for assessing the current and future state of river health by customize an existing framework for assessing the state of river health in Thailand to incorporate future driving factors related to CC and LULCC. This framework is applied to the Songkhram River in the Northeast of Thailand. Additionally, a methodological framework for evaluating and ranking climate models based on extreme climate indices of precipitation and temperature for impact studies in seven sectors: Cryosphere, Energy, Forestry/GHGs, Health, Agriculture & Food Security, Disaster Risk Reduction (flood and drought), and Water Resources & Hydrology was developed. The developed methodology is demonstrated with an application to the Songkhram River, where 18 climate models of CMIP6 were evaluated for the historical period (1979 to 2014). The final top-ranking GCMs for the "Water Resources & Hydrology" sector were selected for climate projection. Assessments are made regarding mean and extreme climate conditions, with reference to the baseline period from 1990 to 2020 and the future period from 2021 to 2050 under two scenarios, SSP2-4.5 and SSP5-8.5. Five land use scenarios (business as usual (BAU), productivity, conservation, urban linear-growth and combination of conservation and urban (CCU)) were constructed and future spatial maps of LULCC were simulated for all scenarios using Dyna-CLUE model. Two LULCC scenarios, BAU and CCU, containing all ranges of development, were used for LULCC impact assessment. The study also projected the future population and gross domestic production for the river basin. The SWAT model was employed to simulate the future river flow and water quality at baseline and in the future for all scenarios of CC and LULCC. For the assessment of river health, variables corresponding to each indicator were computed by analyzing proxy variables and establishing their relationships, resulting in the determination of their dimensions. The projected changes in the river health are assessed under CC and LULCC. Climate model evaluations show variability in performance across different climate indices. Based on sector-relevant indices, ETSCI classified the impact assessments. Under both CC scenarios, the multi-model ensemble projects a decrease in annual average rainfall, with no significant change from the baseline period. Maximum and minimum temperatures show a warming trend of 0.02°C per year. Projections indicate an increase in maximum and minimum temperatures by 1.31°C (0.8–1.6°C) and 1.35°C (0.8–1.9°C) under SSP2-4.5 and 1.56°C (0.9–2.2°C) and 1.63°C (0.9–2.5°C) under SSP5-8.5. River flow under CC and LULCC is projected to decrease by 19.57% under SSP2-4.5 and 21.9% under SSP5-8.5, with slight decreases under both LULCC, which shows CC has a more dominant impact on future flows than LULCC. However, LULCC significantly impacts riverine ecosystems, erosion, and water quality, which is projected to degrade under all scenarios, with LULCC having a greater impact than CC. Biological dimension is expected to reduce aquatic life well-being, for all scenarios. Socio-economically, the river will continue to provide essential services, and exhibit resilience for adaptation to changing conditions. Overall Songkhram River maintains a very good health status during the baseline period across the basin. Under all future scenarios, the future river health is expected to decrease but remain in very good condition. Under both CC scenarios, river health is projected to slightly decrease, followed by BAU and then CCU LULCC scenarios. However, the combined impacts of CC and LULCC have a more pronounced negative effect on river health, following the same sequence as LULCC alone. Spatial variation assessments indicate that the middle basin river health will be most affected in future, especially under the SSP5-8.5+CCU scenario. These findings offer valuable insights for planning restoration efforts and developing adaptation plans to address future changes. |
| Year | 2024 |
| Type | Dissertation |
| School | School of Engineering and Technology |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Water Engineering and Management (WM) |
| Chairperson(s) | Babel, Mukand S.;Shrestha, Sangam (Co-Chairperson) |
| Examination Committee(s) | Salin, Krishna R.;Virdis, Salvatore G.P. |
| Scholarship Donor(s) | AIT Fellowship |
| Degree | Thesis (Ph.D.) - Asian Insitute of Technology, 2024 |