Background

Groundwater is of critical importance to Myanmar’s Central Dry Zone—a 54,000 sq km expanse of land home to almost a third of Myanmar’s population of 54 million people which misses out on much of the monsoon rains which are intercepted by mountains to the west.

To achieve sustainable groundwater development and management within the Dry Zone it is critical to adequately understand the hydrogeological system. During the Groundwater Review of the Central Dry Zone, it became apparent that the age of groundwater was largely unknown. Tritium analysis was undertaken by the Australian Government in 1986, however, most of the groundwater was older than the limits of this type of analysis.

This activity proposed to undertake radiocarbon (C-14) dating of major regional groundwater systems in the Dry Zone as part of the Ayeyarwady State of the Basin Assessment (SOBA). Naturally occurring C-14 in groundwater can be detected and used to estimate its age by giving the approximate time that has passed since the water entered the aquifer based on its half-life, with dating of up to 40,000 years possible.

Objectives

C-14 dating provides empirical evidence for determining the age, mechanism and flow of groundwater resources within the major regional aquifer system of the Dry Zone. The results assist in locating where water enters (recharge) and leaves (discharge) the system, and in understanding the residence time, chemical reactions and flow direction. Therefore, understanding the age of groundwater allows practitioners and the community to better conceptualise groundwater movement and appreciate the need for monitoring and management of this valuable resource.

Outcomes

This activity was undertaken by Aqua Rock Konsultants (ARK) with assistance from the Australian Nuclear Science and Technology Organisation (ANSTO) and the Groundwater Section, Irrigation Water Utilization Management Department of the Ministry of Agriculture, Livestock and Irrigation (MOALI).

Ten groundwater samples were collected from deep tubewells in the Dry Zone by ARK and MOALI and provided to ANSTO in May 2017 for C-14 dating. The results were subsequently incorporated into the textbook on the Hydrogeology of the Dry Zone, Central Myanmar—published by AWP in October 2017.

Understanding groundwater resources has significantly encouraged the adoption of effective management practices by the Government of Myanmar, leading to more efficient and environmentally sustainable water use. View documentation for more information.

Image: Matthew McCartney/IWMI