Groundwater resources Aquifers 27 Hydrogeology 18 groundwater 12 aquifer 10 Groundwater pollution 9 Recharging (underground waters) 7 Landforms 6 Salt water intrusion 6 Fresh Water 4 Groundwater 4 Numerical methods 4 Remote sensing 4 Seawater 4 Water levels 4 Water management 4 Water quality 4 coastal aquifer 4 groundwater flow 4 Agriculture 3 Aquifer systems 3 Decision making 3 Geographic information systems 3 Groundwater flow 3 Groundwater potentials 3 Hierarchical systems 3 Hydraulic conductivity 3 Hydrochemistry 3 Land use 3 Numerical models 3