Here is an interesting story about a unique way of farming in Tunisia that takes advantage of the ability of fresh water to float above saltier water. The farmers take advantage of this property to grow vegetables in sandy crops irrigated by the lens of fresh water. The fresh water reaches the roots of the plants as the ocean tide rises and pushes up the fresh water to the roots of the plants twice a day. You can read more about this unique cropping system, called “ramli”, at https://news.yahoo.com/tunisia-sandy-farms-resist-drought-044609290.html.