Surface water-groundwater interactions: development of methodologies suitable for South African conditions

English: Winter (1999) succinctly, made a profound statement to the effect that understanding the basic principles of the interaction between surface water and groundwater is needed for effective management of water resources. Hence, the research investigation was aimed at identifying appropriate methodologies for assessment of surface water - groundwater interaction, thus enhancing the understanding thereof. The methodology used entailed a review of national and international literature on related previous and current models, systems and methods used in assessment and quantification of water exchange between groundwater and surface water. This was then followed by relevant case study analyses where distinct areas where chosen based on availability of relevant data and information by previous investigators. The findings were that various methods and classification systems are widely available but the applicability thereof under the South African conditions depends on the conceptual understanding of the area or system under investigation, availability of data and the basic assumptions associated with the particular model or method. The surface water - groundwater interaction cannot easily be quantified with confidence without requisite data available. The other finding is that use of multiple techniques to reduce uncertainties and to confirm or verify the existence or non-existence of the interaction is essential. Preferably, at least one method should be utilised to trace flow or qualitatively establish the water exchange while the alternative method is used for quantitative estimation of the interaction between surface water and groundwater. Some of the products emerging from this research investigation include decision tables for choosing applicable analytical method, applicable numerical method and the framework for guiding the selection of appropriate methodologies for assessing or quantifying the interaction between surface water and groundwater. Knowledge generated is applicable to water resource management, resource protection, water allocation and monitoring.