International Journal of Engineering and Technology

This paper presents the results of an investigation of isotope hydrology of the wetland in the Mohlapitsi and Olifants basins. Seventy seven water samples (from boreholes, auger holes, river and springs/drains) were taken during June 2011 through November 2013 for deuterium and oxygen-18 analyses. The springs and groundwater samples appear to form a distinct group, albeit with a wide spread, while the drain water samples (except drain located in MRB206 environment) generally cluster together. Furthermore, river water samples cluster together except water samples at Valis Village crossing and downstream river. The auger hole samples are quite variable with those associated with upstream transects grouping with the drains, while those associated with the downstream transects more similar to the spring. The indications are that the springs have a highly variable signature which may suggest that there are different types of springs to be found in the area; some that are directly associated with groundwater and some that are associated with the drainage of subsurface water circulating above the general level of the regional water table. The isotopic composition of water samples in the study area during low-flow (June 2011 and July 2012) and high-flow (November 2011 and December 2012) periods were similar.