​Madeira is the largest island of the Madeira archipelago, with an area of 737 km². The island was generated during Miocene times until 6000-7000 years B. P. Groundwater resources are the main source of water supply for the 240 500 inhabitants of Madeira island. Groundwater exploitation is made by means of water galleries, tunnels, wells and springs, corresponding to a total volume of groundwater of 185x10⁶ m³ by year for domestic and industrial use, as well as for irrigation and electrical power production purposes. Recharge volume due to rainfall is not sufficient to maintain the actual balance between recharge and discharge at the basal aquifer, suggesting the fog contribution to recharge. 

Madeira island hydrogeological conceptual model includes the following domains: 

-Basal groundwater: occurs after a certain depth. It is formed by geological units of the main and ancient volcanic complexes. 

-Dike impounded grounwater: In the central part of the island, sub-vertical dikes that produce the lateral impoundment of the aquifer. 

-Perched groundwater: It occurs in high parts of the island in relation to low permeability levels.