Spatial variability in stable isotopes from Lesotho surface waters: insights into regional moisture transport.

The Eastern Lesotho Highlands are known as the 'water towers' of South Africa. The hydroclimate of the region is critical for supplying infrastructure within South Africa through the Lesotho Highland Water Project. However, Lesotho is vulnerable to climate change and shifts in moisture patterns could have major implications on water availability with projections indicating that Lesotho may experience water scarcity by the end of the 21st century. Hydrogen and oxygen isotopes of precipitation are important tracers of moisture sources and can be used to better understand hydroclimate processes. However, isotopic data is limited across Southern Africa. This project will consist of two seasonal surface water sampling campaigns in Lesotho to assess the temporal and spatial variability of moisture sources through isotope analysis. The data will be integrated with back trajectory HYSPLIT modelling to provide a better understanding of moisture source pathways. This information can then be used to help inform policy makers to improve water resource management within Lesotho and South Africa.