SWAMPSCOTT – Farouk El-Baz can see through sand.Just how the Boston University professor accomplishes such an amazing feat was unveiled Monday to a group of about 50 student activists at Swampscott High School.El-Baz is director of the university’s Center for Remote Sensing, and through that role has access to some of the world’s most sophisticated imaging machines. In this case, he monitors satellite data after it captures sunrays reflecting off regions of interest on Earth.The radiation patterns can reveal what the geologic composition looks like beneath the surface. In other words, the technology can locate water beneath the seemingly endless desert sands that cover much of North Africa.Imaging results culled from an earlier El-Baz research project are already in action in Egypt where 500 wells pump drinking water from an underground lake that nobody knew existed until the scientist led them to it.El-Baz visited the high school on a request from U.S. Rep. John F. Tierney, a Salem Democrat and chairman of the National Security and Foreign Affairs Subcommittee. The students sent letters to Tierney’s office, expressing concern about human rights issues, particularly those involving the Darfur region of Sudan, where a 21-year bloody civil war continues and drought is an everyday occurrence. The congressman, in turn, introduced them to El-Baz, whose wife, Patricia, is a Swampscott High graduate.”I am a desert expert. I have an understanding of sand,” said El-Baz, engaging the students to think about the transformation of rock. “Sand is born by water and only shaped by the wind.”El-Baz explained that it rains only once every 20-50 years in parts of North Africa. “You can drive 500 miles and not see a single blade of grass,” he said, but it most likely was not always this way. Ancient rock paintings or petroglyphs discovered in the region depict animals, including giraffes, which suggests the land may have been previously covered with vegetation.Nobody knows what happened to the water, but it’s possible the lake seeped into the porous rock and is now underground, perhaps 1,000 feet below the surface, just waiting to be pumped and piped to thirsty inhabitants.According to El-Baz, whose findings have attracted the attention of the United Nations, getting water from underground could take months, not years, presuming the necessary funding is provided. The subterranean lake could be the size of Massachusetts, he said.Ideally, such a massive water resource would eliminate some of the tension that is fueling the Sudanese civil war. The fighting is often about water and access to wells.The climate in Sudan is cyclical and tends to follow a pattern of drought for seven years followed by seven years of adequate rainfall. When water is scarce, the people tend to move, and fighting is often the result because the regions into which they relocate already face shortages.While El-Baz’s approach leans on technology, Sudan is also the focus of an international investigation into genocide. Most of the guns used in its civil war are supplied by China, which is the largest importer of Sudanese oil.The Chinese do not want other countries telling them what to do, so other ways must be found to apply pressure, Tierney said.The students asked the congressman what they could do to affect change. His advice: write letters to the White House, to Congress, to newspapers and to the CEOs of companies that plan to provide sponsorship at the 2008 Olympics in Beijing. “Keep the pressure on and raise awareness,” he said. “Raise money for the refugees.”Another strategy is convincing investment companies to divest their holdings in countries with poor human rights records. Unfortunately, some of those investments are profitable, and investors have a fiduciary responsibility to make as much money as possible for their clients, he said.