Design of preliminary groundwater monitoring networks for the coastal Tra Vinh province in Mekong Delta, Vietnam

Abstract

Study Region: The study region is the coastal Tra Vinh province located in Mekong Delta, Vietnam Study Focus: The objective of the study is to design preliminary monitoring networks for groundwater level and salinity monitoring in the three heavily abstracted aquifers in the Tra Vinh province. Since data from the existing monitoring were insufficient to explore variogram analysis and subsequent Kriging interpolation for the network design, groundwater flow and saltwater transport models were constructed to create groundwater level and salinity distributions. An iterative procedure was adopted to select monitoring well locations based on the contour maps of groundwater levels and total dissolved solids (TDS) constructed from the groundwater models. The standard deviation of Kriging interpolation error was used as the criteria to assess the quality of the designed monitoring networks. Priorities for the locating groundwater level monitoring wells were targeted in areas with cones of depression and boundaries, while priorities for salinity monitoring were given to coastal zone and inland fresh/saltwater interfaces. New Hydrological Insights for the Region: Groundwater overexploitation has resulted in storage depletion and saltwater intrusion in the Tra Vinh province. Simulations from the numerical models determined the cones of the depression and predicted intrusion from inland saltwater trapped in clays from past marine transgressions and from seawater in the coastal zone. A limited number of monitoring wells is operated and is insufficient to delineate the cone of depression and fresh/salt water interfaces. This study combined the numerical model simulation results and Kriging interpolation method and designed preliminary groundwater level and salinity monitoring networks for the Tra Vinh province. Once the designed networks are implemented, observed data from the networks will provide valuable information for sustainable groundwater resources management in Tra Vinh province. Data availability: All data generated or analyzed during this study are available upon request from the corresponding author.

Keywords

• Coastal groundwater
• Saltwater intrusion
• Monitoring network design
• Groundwater models
• Kriging interpolation