Dunes move - it's what they do, it's what makes them dunes as opposed to lifeless piles of sand; and nothing will stand in their way. The images above are of dune invasion in the Bahariya oasis of Egypt's Western Desert, but to see a moving National Geographic video of the human cost of dune encroachment, follow the link at https://geology.com/news/2009/shifting-sand-dunes-bury-homes.shtml.
The video is from Mauritania, but in towns and villages throughout the Sahara, houses engulfed by sand are abandoned, to be reoccupied, perhaps by the next generation of the family, after the sand dune has moved over and onward. Fields and palm groves are treated the same way—but the palms will be dead and new ones will need to be planted. Huge amounts of money have to be spent keeping roads and railways clear of sand or rebuilding them. There are ways of inhibiting the march of the dunes - but I'll leave that fascinating topic for a later post.
Arawan, the once-thriving oasis north of Timbuktu used to serve the camel caravans from the salt mines further north, but for a long time now the visitors have been dunes rather than traders. And the women of Arawan shovel sand, every day when the wind is not blowing too hard. It’s not that they haven’t always lived with sand, being, after all, in the middle of the Sahara; but in the 1960s and early 1970s a series of devastating droughts destroyed much of the vegetation, and the sand began to move. The mosque was buried, trees were engulfed, and the wells had to be reexcavated. Dunes encroach on the roofs of houses, the owners keeping only the doorway clear. The sand women are professionals, often paid in rice or sugar to shovel the surrounding dunes, energetically but for the most part futilely.
The video discusses desertification. Moving dunes do not signal desertification, but expanding seas of sand, the ergs of the world, do. It's a controversial topic and the evidence for desertification around the fringes of the Sahara is not always clear-cut. What is clear, however, is that where the Earth's arid regions are expanding, where desertification is taking place, more often than not it's our fault - and not through climate change. The most dramatic, and potentially catastrophic, example is that of China. More than a quarter of the total area of China, over 2.5 million square kilometers (a million sq mi)—about four times the area of the state of Texas—is covered by deserts. Four of these—the southern Gobi, the Alashan, the Taklimakan, and the Tengger—are more or less connected to form the vast arid interior. The total area of China’s deserts is growing at around 200 square kilometers (80 sq mi) every month, and every year tens of thousands of tons of sand and dust are blown into Beijing. China’s capital has always suffered from dust storms, helped again by the ice age, when grinding glaciers wore rocks down to flour, technically known as loess, which, once airborne, blankets huge areas for long periods of time. But Beijing’s dust storms are turning into sandstorms. It’s not necessary to travel to the Gobi Desert to find encroaching sand; it’s a mere hour’s drive out of Beijing. The Great Wall, built to defend against invaders from the west, is proving no match for the onslaught of sand: whole sections are being destroyed by the storms.
In the village of Longbaoshan, dunes are consuming the houses, and digging has become a way of life. In the region where forests and lakes once provided the hunting grounds for emperors, sand dunes move across the landscape at 20 meters (65 ft) per year. Entrepreneurs have benefited from tourists and filmmakers traveling to Longbaoshan from Beijing in quest of desert landscapes, but a villager's narrative brings us back to the human cost: “Sometimes I dream of the sand falling around me faster than I can dig away. The sand chokes me. I worry that in real life, the sand will win."
Today’s inhabitants of villages like Longbaoshan can point to dusty, bare hillsides and valleys that they remember being verdant. It is estimated that firewood collection, excessive grazing, and overcultivation account for close to 90 percent of recent desertification. For many areas of the world where sand is threateningly on the move, it is not nature, but humans that are the cause, and, as for the woman in the video, it's humans that suffer the consequences.
[fora good article on Longbaoshan and Chinese desertification, see https://www-cgi.cnn.com/ASIANOW/asiaweek/magazine/2000/1013/is.china.html; the quotation is from this source. Photos by myself and Google Earth]