Exploration of shallow sandy ridge systems for aquifer storage and recovery solutions in the Vietnamese Mekong Delta

Abstract

Especially in recent years, the Vietnamese Mekong delta has experienced extreme saltwater intrusion, affecting surface waters further inland than ever before, causing hundreds of millions of dollars in damage. Due to the desired economic growth of the Vietnamese Mekong Delta, fresh groundwater resources are intensively exploited to meet up water demand needed for food, domestic use and industrial activities. The food productivity of the Mekong Delta responsible for 50% of the food supply of Vietnam. The over exploitation of the water resources causes freshwater scarcity which leads to land subsidence and saltwater intrusion of both groundwater and surface water. In this study, a solution to shallow ground water scarcity is investigated. Here, the feasibility of an aquifer storage and recovery (ASR) solution is evaluated. focussing on shallow phreatic sandy ridge aquifers in the provinces of Tra Vinh and Ben Tre in the Mekong Delta in Vietnam. These solutions have been successful in the Netherlands on similar geomorphological features, and thus, it is investigated if the implementation of these systems could also be a promising way to provide freshwater security in the Mekong Delta, Vietnam. An analysis of the geological architecture of the sandy ridge structures was explored during a three- month field campaign at three potential sites. Using shallow suction coring, deep coring and cross section analysis, the sandy ridges were evaluated in terms of lithology, storage capacity, and ultimately, feasibility for an ASR solution. At least one such site in the province of Ben Tre shows future potential of an ASR pilot. A suitability map was developed to upscale the potential of additional sites in the two investigated provinces that could benefit the most from an ASR system. Zones with sandy ridge structures, that irrigate during the dry season and experience saltwater intrusion into the surface water systems stand to be the areas that can benefit the most from an ASR system. With increasing water demand, expanding innovative water management techniques is an important component moving towards a more sustainable future of the supply of freshwater and food in the Vietnamese Mekong Delta.