A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Water Engineering and Management

Thesis (M. Eng.) - Asian Institute of Technology, 2023

In Vietnam Mekong Delta (VMD), groundwater is one of the main sources of water resources causing the drop of groundwater table. So, it is important to conserve groundwater, and Ecosystem-based Adaptation (EbA) appears to be a promising method for doing so on a local level. Tra Vinh Province, one of the provinces in VMD has experienced depletion of groundwater. Thus, this study aims to assess EbA to lessen the effect of stressors on groundwater in Tra Vinh Province. In this study, firstly, non-parametric statistical tests were conducted on 13 observation wells monthly time series data to identify the current status of groundwater. Secondly, surveys were conducted in different communities & literatures were reviewed to identify potential stressors on groundwater & people{u2019}s willingness to accept EbA. Lastly, GMS MODFLOW calibrated & validated using observation well time series data in the steady state, was used to develop a conceptual groundwater model for the study area for analyzing the impact of stressors & assessing EbA to mitigate the stressors{u2019} impacts. For the years 1994 to 2018, we discover that the province's groundwater has been declining at a rate of 27.8 cm per year. From survey data and literatures, over-extraction caused by dependency on groundwater, urbanization and agriculture are main anthropogenic stressors on groundwater, along with variations in rainfall as a natural stressor. From model, increased pumping and decreased recharge caused by stressors decline groundwater level by 1.18 m and 1.09 m on average with respect to base case (2021), respectively. The most effective EbA measure is to protect the Groundwater Dependent Ecosystem that increase groundwater level by 1.53 m on average while the most preferred EbA measures, protection of critical recharge zone increases water level by 0.86 m on average with respect to base case (2021). So, it is concluded that EbA are preferred by people as they are willing to conserve groundwater and it can lessen the impact of stressors on groundwater and improve groundwater status.