资源环境科技发展态势分析平台

Tritium (³H) has become synonymous with modern groundwater and is used in a myriad of applications, ranging from sustainability investigations to contaminant transport and groundwater vulnerability. This study uses measured ³H groundwater activities from 722 sample locations across South Africa to construct a ³H groundwater distribution surface. Environmental co-variables are tested using geostatistical analysis to constrain external controls on ³H variability, namely: [1] depth to groundwater, [2] distance from the ocean and [3] summer vs winter rainfall proportion. The inclusion of co-variables in the ‘fit’ of residual variograms improved prediction variance significantly yet does not mitigate issues with sample density. The distribution of ³H in groundwater agrees well to expected controls, with proximal (<100km) coastal regions, winter rainfall zones and greater depth to groundwater predicted to have lower ³H activities. Conversely, inland localities with shallower depth to groundwater and/or summer rainfall are predicted to have elevated ³H activities. Some ³H high and low anomalies cannot be explained by known phenomena and may simply be regions of variable recharge and/or longer isolated groundwater flow paths. Regions that receive modern groundwater recharge are more vulnerable to climate change as well as modern pollution. Less actively recharged groundwater may be more resilient to climate change yet represents a potentially non-renewable resource for abstraction in South Africa. The application of ³H distributions in the assessment of hydrological resilience is pertinent to effective groundwater management studies.