Assessment of subsurface contamination along Bang Yai Canal in Phuket using contaminant transport modelling | |
| Author | Ranasinghe, Achini Uppeka |
| Call Number | AIT Thesis no.GE-20-10 |
| Subject(s) | Hazardous waste site remediation--Thailand--Phuket Heavy metals--Thailand--Phuket Hydrologic models--Thailand--Phuket |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Geotechnical and Earth Resources Engineering |
| Publisher | Asian Institute of Technology |
| Abstract | The long history of tin mining in Phuket island has polluted sediments in rivers, estuaries, and lakes. Although metal discharges were greater during the period of active tin mining in the eighteenth century, a significant amount of dissolved heavy metals still occur in the aquifer system. When the water flows through the abandoned tin mining area, it gets contaminated. This contaminated discharge then enters the nearby waterways which eventually connects to the Bang Yai canal which is the largest river located in Phuket. Due to the river processes, the metal contaminants present are transported downstream and deposited in the canal bed. Often, the contaminants travel a considerable distance downstream from the mining sites. Since metals are nonbiodegradable, it remains in the environment for a long period. Thus, it is important to investigate the heavy metal contamination at present and in the next few decades. This study aims to investigate the present heavy metal contamination along the Bang Yai canal and predict the future state of the contaminant dispersion through numerical modelling. A three-dimensional coupled numerical model of groundwater flow and mass transport was developed using the Visual MODFLOW software with MODFLOW 2005 and MT3DMS engines. An initial simulation (2009-2018) of the groundwater flow model was performed under the transient state and it was calibrated for four particular years (2009, 2010,2011 & 2014). Based on the calibrated groundwater flow and transport parameters, the contaminant transport model simulation was executed, and it was validated for the year 2018. As the calibration and validation results were within the acceptable range, the contaminant transport model was expected to effectively represent the contaminant dispersion for the predictive simulation period of 30 years (2019-2048). It was observed that the groundwater flows in the direction of the dominant slope (NW to SE) and the overall heavy metal concentrations will be reduced over the 40 years. Also, the contaminant concentration in the canal is reduced rapidly in the first 15 years and follows a gradual decrement in the next 25 years. However, the contaminant concentration in the land decreases linearly over the 40 years. |
| Year | 2021 |
| Type | Thesis |
| School | School of Engineering and Technology (SET) |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Geotechnical Engineering (GE) |
| Chairperson(s) | Avirut Putiwongrak; |
| Examination Committee(s) | Chao, Kuo Chieh;Pham, Huy Giao; |
| Scholarship Donor(s) | Asian Institute of Technology Fellowship; |
| Degree | Thesis (M. Eng.) - Asian Institute of Technology, 2021 |