La Aldes ravine, located on the western side of Gran Canaria (Canary Islands), presents a flat bottom surrounded by high mountains (with heights varying from sea level to 1,415 m). The climate is dry subtropical with high temperatures throughout the year. Intensive greenhouse horticulture (mainly tomatoes and cucumbers) is practiced with a cultivation surface of 645 ha and irrigation water is mainly supplied by three dams situated upstream, although more than 370 large-diameter wells also provide crop water requirements in the dry season, diminishing the quality of groundwater.