Increasing salinity intrusion into estuaries
The chance of extreme saltwater intrusion in estuaries worldwide will increase by ten to twenty percent by 2100 as a result of changing river flows and rising sea levels caused by climate change. This was calculated by researchers from Utrecht University and Deltares in a joint publication in Nature Communications. This study emphasises the need to include the salinisation of estuaries in the approach to climate adaptation.
Download the paper in Nature Communications
Climate projections for salt intrusion
Saltwater intrusion in rivers threatens the availability of fresh water in coastal areas worldwide. This problem is expected to increase as a result of climate change. In this study, the researchers determined the changes in saltwater intrusion statistics under the influence of climate change for eighteen river systems around the world.
To this end, they determined predictions of river discharge and relative sea level rise from climate model simulations and then used these to make projections of salt intrusion up to the year 2100. This study is the first to take into account the combined effects of changes in river discharge and sea level rise on salt intrusion on a global scale.
River discharge and sea level rise
For most of the river systems studied, the projections indicate that the combined effect of changing river discharges and sea level rise will lead to an increase in extreme salt intrusion of ten to twenty percent by 2100. In the coming decades, reduced river discharge caused by climate change will pose the greatest threat to the availability of fresh water.
The study shows, however, that by the end of this century, the rise in sea level will contribute approximately twice as much to the increase in saltwater intrusion as the reduced river flow. The level of saltwater intrusion that occurs once every hundred years is expected to increase to twenty-five percent.
Effect
Increased salt intrusion may not be as visible a consequence of climate change as coastal flooding. However, the consequences for the availability of fresh water, health, agricultural yields and the quality of life in deltas can be significant and affect millions of people.
‘The results of this study emphasise how important it is to include changes in saltwater intrusion, their consequences and measures to combat them in climate adaptation plans, in order to contribute to liveable deltas in a changing world,’ says co-author Wouter Kranenburg, saltwater intrusion expert at Deltares.
SALTISolutions
This research took place within the framework of the NWO-funded Perspectiefprogramma SALTISolutions and the Deltares project ‘Salt Intrusion around the World’, initiated under the strategic research mission of Deltares ‘Liveable Deltas in a Changing World’.
Lead author Jiyong Lee was a postdoc at Utrecht University under professor of climate physics Henk Dijkstra and professor of physical oceanography of the coastal zone Huib de Swart. Deltares experts who contributed to this study are Wouter Kranenburg, Ymkje Huismans and Daan van Keulen.
