Analysis of salinity intrusion and alternative solutions for municipal water supply in Bangkok under climate change conditions | |
| Author | Chirayu Jaroenongard |
| Call Number | AIT Diss no.WM-23-04 |
| Subject(s) | Climate change mitigation--Thailand--Bangkok Climatic changes--Thailand--Bangkok Saltwater encroachment--Thailand--Bangkok Water-supply--Thailand--Bangkok |
| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Engineering in Water Engineering and Management |
| Publisher | Asian Institute of Technology |
| Abstract | Climate change (CC) induced sea level rise (SLR) and changes in rainfall adversely influence salinity intrusion in coastal areas and it’s important to quantify their impacts to formulate possible solutions. This study assessed the impacts of CC on salinity intrusion in the Chao Phraya River (CPY), from where the Metropolitan Waterworks Authority (MWA) takes raw water for the municipal supply and evaluates alternative solutions for maintaining the required water quality for municipal water supply. Future projections of rainfall and sea level are carried out using 20 climate models for three future periods (near: 2021-2050, mid: 2051-2080, far: 2081-2099). 3 land subsidence and 4 water demand scenarios are formulated. MIKE11 is used to simulate the future flows and salinity in CPY. Annual rainfall is projected to increase by 6% (8%), 14% (18%), and 19% (25%) during near, mid, and far future periods for RCP4.5 (RCP8.5), respectively. Relative SLR in UGoT will increase 0.94mm/year (1.07mm/year) with no land subsidence to 1.05mm/year (1.18mm/year) with land subsidence under RCP4.5 (RCP8.5) in the 21st century. From the baseline period with average of 35 events per year with salinity >0.25g/L, by 2100, number of events could increase to 170-190 per year with average duration of 16.5 hours per day. If the water demand increases by 15%, duration of such event could be 22.3-22.8 hours/day by far future. Shifting the raw water intake up to 80km upstream of the current location could be one of the solutions for projected high salinity due to CC and increase in future water demand. The second alternative is to divert the water from another freshwater source or to collect the water in a storage system during low salinity. Analysis showed that a storage volume of 5.1Mm3 water of permissible salinity would address the salinity problem for 95% of events in the near future. If future water is assumed to be constant, a storage volume of 6.1Mm3 would be sufficient for the far future. The analysis revealed that future SLR due to CC in the UGoT will not be as severe as globally averaged projections. Although the projected increase in rainfall may have a conducive impact on salinity in the future period, SLR and increase in water demands in the upstream catchment will dominate the future salinity in CPY. A possible mitigation is a progressive shifting of the intake upstream of the current location and planning for water storage to be used during high river salinity. Although the study has comprehensively quantify impact of CC and water demand change, the results are still associated with model-related uncertainties, hydrological modeling, emission scenarios, etc. Nevertheless, the study would contribute to the CC knowledgebase for the CPY and be useful to MWA and other government entities for planning strategies to combat the adverse impacts of climate change on municipal water supply in Bangkok, Thailand. |
| Year | 2023 |
| 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) | Sutat Weesakul;Vilas Nitivattananon; |
| Scholarship Donor(s) | Metropolitan Waterworks Authority (MWA),Thailand;Asian Institute of Technology Fellowship; |
| Degree | Thesis (Ph. D.) - Asian Institute of Technology, 2023 |