Methods to supply seawater to desalination plants along the Spanish mediterranean coast and their associated issues

Many coastal areas of our planet receive only scarce precipitation, and have limited or often non-existent surface water resources. Over the last four decades, the intensive agriculture and tourism along the Spanish mediterranean coast have led to a large increase in water demand. The economic development of this, the most arid stretch of the Mediterranean coast has been dependent on the availability of good quality groundwater. Desalination in Spain has contributed to the progress and development of these areas, being considered as the solution to this increased demand. Along the Spanish mediterranean coast, around 30 desalination plants of medium–high capacity, between 20,000 and 125,000 m³/day, have been built over the last 25 years, and there are several plants in the planning stage, to be constructed in the near future. In addition, 100 small plants desalinate brackish water. Desalination plants are usually supplied from coastal boreholes if there is a coastal aquifer with hydraulic connection to the sea. Nevertheless, the water to desalinate in other cases comes from evaporitic aquifers or even fossil water. Regarding the water intake systems, horizontal directional drilling can give good results, not to mention a number of other sophisticated and curious designs, each with their particular advantages and drawbacks. This paper describes the main problems and also the benefits concerning water intake systems to some desalination plants along the Spanish mediterranean coast.