Connectivity of geohydrological processes and the interaction with the surface hydrology of the Letaba River

English: Continued population and economic growth within South Africa have led to increased water use by industry, agriculture, mining, domestic users and other uses over the past few decades. This increased usage has come close or even surpassed the threshold of renewable water resources within river basins. It was recognised that South Africa faces significant challenges in terms of water reform, involving major administrative and policy shifts, thus the attention has shifted to implementation. Water resource management has become of utmost importance to ensure that water users still receive an adequate supply, while at the same time the environmental flows are managed. Surface and groundwater processes have typically been studied as separate disciplines, regardless of their obvious association. They are both components of the hydrologic system however, they are not isolated components and interact in a range of climatic and physiographic landscapes. Thus, the contamination over usage or development of one affects the other. Consequently, a better understanding of the primary principles of the connectivity between the groundwater and surface water is essential for the successful management of water resources. This is particularly true upstream of the Kruger National Park, because of the limited understanding of groundwater – surface water interaction within catchments. This resulted in the initiation of this dissertation to determine the connectivity of geohydrological processes and the interaction with the surface hydrology of the Letaba River, to ultimately provide guidance for successful management of water resources. There are many techniques to measure groundwater – surface water interaction, although for this dissertation the following methods were implemented: hydraulic gradients, geological characterisation, aquifer characterisation, fluid logging, environmental tracer method and the chemical base flow separation method. All of the results were then incorporated to provide a final conceptual model, indicating the interaction between the geohydrology and hydrology of the Letaba River. The study site had to be divided into four transects, because of the scale. As anticipated, a simple losing or gaining stream was not indicated by the analyses. But, rather a complex system of groundwater movement and interaction with the surface hydrology for each transect, ultimately changing with seasonal variability and peak flow conditions. It has become clear through this research that the connectivity between the surface water and groundwater is extremely complex. Thus, indicating the importance of groundwater management to protect and provide sustainable development for both resources. Even though a good infrastructure for data capturing have been implemented certain gaps are still found. Further research and monitoring is essential to ultimately fully understand this complex interaction.