1. Flinders University and National Centre for Groundwater Research and Training, College of Science and Engineering, GPO Box 2100, Adelaide 5001, Australia. (corresponding author)
2. The University of Adelaide, School of Physical Sciences, Adelaide 5005, Australia.
3. Flinders University and National Centre for Groundwater Research and Training, College of Science and Engineering, GPO Box 2100, Adelaide 5001, Australia.
4. International Water Management Institute, P.O. Box: 4199, Ban Nongviengkham, Xaythany District 01170, Vientiane, Lao PDR.
5. National University of Laos, Physics Department, Faculty of Natural Sciences, Dong Dok Campus, PO Box 7322, Xaythany District 01170, Vientiane, Lao PDR.
6. Ministry of Natural Resources and Environment, Department of Water Resources, P.O. Box 7864, Vientiane, XHXM+C8M, Vientiane, Lao PDR.
7. National University of Laos, Department of Water Resources Development and Management, Faculty of Water Resources, Dong Dok Campus, PO Box 7322, Xaythany District 01170, Vientiane, Lao PDR.