Groundwater/seawater interaction (GSI), as a major form of ocean-land interplay, is associated with two potential pathways of dissolved material transport, namely (1) flux from the marine to the terrestrial environment caused by seawater intrusion into a terrestrial aquifer and (2) flux from a terrestrial aquifer to the coastal ocean manifested as submarine discharging groundwater. The sea-to-land pathway is of relevance (i) due to the risk of salinization of coastal groundwater resources. The land-to-sea pathway, on the other hand, is of concern due to two potential threats, namely (ii) the detrimental impact of nutrient- or contaminant-laden groundwater discharge on the coastal water quality, an aspect that is of relevance along most coastlines worldwide, and (iii) the loss of freshwater to the ocean, an issue which is of particular interest in climate zones with (seasonally) limited groundwater recharge rates and thus limited freshwater availability. All three aspects are of relevance in the project target area, the South African south coast.

The approach involves both the marine and the terrestrial perspective by investigating purely marine environments, marine/terrestrial interaction processes as well as the vulnerability of coastal aquifers. It entails the multifaceted application and interpretation of a range of state of the art and innovative methodologies that reach beyond using standard parameters and indicators for the assessment of risks related to coastal water quality, aquifer vulnerability and land use change. Besides the resulting beneficial effects for the study regions, the activities will also improve the related methodological repertoire of the participating research institutions, also for the benefit of participating young researchers. The project consists of following sub-projects (SP):

  • Sub-project 1: Remote-sensing groundwater system characterisation – A multimethodological approach
  • Sub-project 2: Localisation and quantification of submarine groundwater discharge using environmental tracer
  • Sub-project 3: Effects of groundwater discharge on marine macrozoobenthos
  • Sub-project 4: Land use (changes) and groundwater vulnerability