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.