Negative hydrodynamic barriers: an effective system to reduce the freshwater discharge into the sea

Abstract

The growing demand for water is a widespread problem, especially in arid and semi-arid areas. Coastal areas are particularly sensitive to this problem, although in these areas there is the paradox that coastal aquifers naturally drain large volumes of freshwater into the sea through submarine discharge. In this work we propose, for the first time, the use of negative hydrodynamic barriers as an effective system to reduce the volume of these discharges. For this purpose, the aquifer of the Andarax river delta has been studied, where the presence of a set of boreholes that capture the saline water wedge penetrating the aquifer. This would be acting as a hydrodynamic barrier, which on the one hand prevents the advance of the saline wedge to the continent, and on the other hand, the outflow of freshwater to the sea. The problem with this type of barrier is the economic cost linked to the energy consumption required to continuously pump saline water, so its use would only be appropriate where there is a desalination plant that is supplied with saline water from the wedge that penetrates the aquifer.