Approaches to modelling saline intrusion for assessment of small island water resources

The current approaches to modelling the groundwater resources of small isla nds are briefly reviewed and the importance of representing the variation i n salinity through a transition zone between the freshwater lens and sea wa ter is emphasized. Older approaches based on a sharp interface approximatio n are inappropriate. The current modelling approach is based on the advecti on-dispersion equation. However, key parameters in this equation are scale, density and problem specific, making the approach difficult to use predict ively. The density dependence is illustrated by simple analytical results a nd experiments, and future consideration of this dependence is advocated. A lternative modelling approaches are identified, and investigation of their usefulness is recommended.