![]() ![]() In general, rainfall is irregular, from 100 mm in the south to 900 mm in the north of the islands (Gonzalo et al., 2017). There are island systems and areas which due to the low contribution of rainfall (Díaz, et al., 2011), between 100 and 250 mm/year, do not have the necessary aquifer recharge to satisfy water demand. Lanzarote is an island where agricultural water consumption is substantial, though the urban and tourism water demand is greater. In Lanzarote, the supply is practically all from desalination with a percentage that exceeds 80%. The urban supply, in Fuerteventura, is provided by seawater desalination plants. ![]() These water resources are mainly used in agriculture. However there are certain exceptions for instance, in the case of Gran Canaria, there are significant underground resources, extracted mainly from wells, as well as surface resources, stored by an extensive network of large dams (about 60) (Santamarta, 2014). ![]() In the eastern islands, the water supply comes mainly from seawater desalination plants (reverse osmosis). As for surface water resources, their quantity is not especially important in this group, and they only have some relevance in La Palma and La Gomera (Table 1). As an exception, it should be noted that on the island of La Palma, there are no desalination plants providing water from the sea to supply the population. Groundwater is complemented to a lesser extent by supply from desalination plants, especially on the island of Tenerife. In the western islands, water consumption is mainly supplied by groundwater in some cases such as in Tenerife and La Palma, the percentages exceed 80% of total supply. Regarding the water resources in the Canary Islands, there are two operating models: the western model (Tenerife, La Palma, La Gomera and El Hierro) and the eastern one (Gran Canaria, Fuerteventura and Lanzarote). In short, it is the official document to know the hydrological status of each island, as well as to know the future trends of the island. This is a document that includes all the specifications of the hydrological cycle of each island, an inventory of all the water facilities on the island establishes the hydrological balance and estimates the recharge of the aquifer. ![]() Water planning on the islands is conducted through an Island Hydrological Plan, which is the basic instrument of hydrological planning, aimed at achieving the best possible way to meet all the islands’ water demands. Currently, and with new regulations such as the Water Framework Directive, which is an EU Directive (Quevauviller, 2009), there is a tendency to conduct water management based on demand, giving priority to guaranteed and efficient water resources. The environment was an irrelevant issue in the decision-making process in the field of hydrology. Thirty years ago, hydrological planning in the Canary Islands was about increasing the water supply without considering the environmental or economic limitations, since this resource was necessary at any cost and was the basis of the islands’ economic development. This common origin means that similar solutions may be found to problems shared by the islands, such as guaranteeing water supply, erosion control and soil conservation, as well as safety from major floods and landslides (Hughes & Malmqvist, 2005). Oceanic islands have common patterns with respect to water resources with certain specific features, due among other reasons to (i) geological age, (ii) typology of the volcanic island, (iii) average altitude and orography, (iv) type of vegetation, (v) geographical location, (vi) volcanic constituent materials, and (vii) average rainfall (Santamarta et al., 2014). ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |