The Development of Geochemical Sensor Arrays for Optimisation of Coastal Groundwater Resources

The problem of salt-water intrusion makes it difficult to maximise the full potential of coastal groundwater resources. Management techniques, such as salt-water intrusion barriers, artificial recharge and recovery, and groundwater optimisation models have been employed in attempt to maximise yield from these aquifers. In spite of these efforts, without a well developed monitoring and warning system for salt-water intrusion, the full potential of the coastal aquifer cannot be achieved. Online sensors that provide real-time, constant measurements can fulfil this need. At Roskilde University, an array of solid-state sensors, including Na+/K+, Ca+2, Cl-, conductivity cells and pH, which can provide continuous, real-time groundwater chemistry data, are currently being developed for use in groundwater production wells. The sensors are being developed based on a new, solid-state technology which will enable the sensors to provide continuous data in groundwater wells. Laboratory tests on the Na+/K+ and Cl- sensors have shown a constant, stable response to changes in respective ion concentrations. These results illustrate the promise of the technology for use on salt-water detection in operating groundwater wells and the interactive management of coastal groundwater resources. However, testing and development of the sensors in the array is still ongoing, with further testing, particularly in the field, needed.