‘Air curtain’ study addresses salinity

It could be used to restrict the intrusion of salt water from the sea into rivers when water levels in those rivers are at a low level. Laboratories at Deltares’ facility in Delft will work with Texas A&M University in the US to carry out scale model tests and computer calculations.

Previous studies carried out by Deltares have shown that an air curtain is a feasible and cost effective way to restrict salinity in the Rhine-Meuse estuary. “We are now studying how to use this curtain more effectively and in the most energy saving and cost cutting way, taking into account the varying tidal and river discharge conditions in the New Waterway”, said Deltares.

Until now, air curtains based on bubbles have only been used to restrict salinity in Dutch and foreign waterways, but it is anticipated that their use could become much more widespread .The bubbles work by entraining fresh water and restrict the ingress of more saline water.

Deltares’ project leader Yann Friocourt explained that injecting too little air makes the bubble curtain less effective; too much air will cost a lot of unnecessary energy. “Using scale models, we want to gain a better understanding of the process, how much air should be used and how flow rate and stratification affect the process.”