Almost 40 percent of the world population lives in coastal areas, less than 60 kilometers from the shoreline, Mizuno said. These regions may face loss of freshwater resources more than we originally thought.
Scientists have used the IPCC reports to draw maps of how the world's coastlines will change as waters rise, and they have produced some of the most striking images of the potential consequences of climate change.
Ibaraki said that he would like to create similar maps that show how the water supply could be affected.
That's not an easy task, since scientists don't know exactly where all of the world's fresh water is located, or how much is there. Nor do they know the details of the subterranean structure in many places.
One finding of this study is that saltwater will penetrate further into areas that have a complex underground structure.
Typically, coastlines are made of different sandy layers that have built up over time, Ibaraki explained. Some layers may contain coarse sand and others fine sand. Fine sand tends to block more water, while coarse sand lets more flow through.
The researchers simulated coastlines made entirely of coarse or fine sand, and different textures in between. They also simulated more realistic, layered underground structures.
The simulation showed that, the more layers a coastline has, the more the saltwater and fresh water mix. The mixing causes convection -- similar to the currents that stir water in the open sea. Between the incoming saltwater and the inland fresh water, a pool of brackish water forms.
Further sea level rise increases the mixing even more.
Depending on how these two factors interact, underground brackish water can extend 10 to 50 percent further inland than the saltwater on the surf
|Contact: Motomu Ibaraki|
Ohio State University