(
课件网) AlUla: Mastering the Desert's Water Adapted from National Geographic 202307 Humans can survive longer without food than without water, significantly longer. It's one of the harsh realities that makes the dry deserts of Saudi Arabia (沙特阿拉伯) such a challenging place to live. Then there's the searing① heat in a landscape that offers little shade, and the often infertile sands in which plants struggle to grow. It seems an unlikely place for farms, cities, and civilizations to emerge②. But that's what happened in the AlUla valley between the foothills of Saudi Arabia's Hijaz Mountains. Because even in the desert, there are places where water can be found to nurture③ life and allow plants, animals, and humans to thrive. The AlUla valley cradles④ an oasis⑤， an island of habitable⑥ land amid Saudi Arabia's vast seas of sand, a haven⑦ that can support communities. The story of AlUla begins millions of years ago when a wetter climate carved a huge water catchment (汇水) of great valleys that fed the wadi (干谷) that runs through the region. Much of the water flows through underground systems, becoming trapped and stored as an aquifer⑧. Topped up by distant rains, the aquifer raised the water table⑨ close to the surface to create a wetland in which plants could grow, and to this rare source of food and drink flocked animals and, ultimately, humans. AlUla's earliest inhabitants lived a nomadic⑩ hunter-gatherer lifestyle, perhaps shading beneath trees, and hunting gazelle while drinking from natural springs and pooled water at the surface. But AlUla was blessed with more than water: it also had fertile soils. This enabled later successive peoples to settle and develop irrigated agriculture, growing crops ranging from palm dates (椰枣) and citrus (柑橘) fruits to wheat and barley (大麦), creating the oasis. In order to sustain an oasis, humans must find, manage, and use the available water wisely. While water bubbling up from natural springs and seasonal rains might temporarily fill wadis, to make the most of it, people needed to take control of the water. One of the earliest ways was to dig wells. The wells stored vast volumes of water for long periods, supporting AlUla's people and agriculture. Another sophisticated water-management system emerged: qanats (坎儿井). These gently sloping underground channels tapped into the water table at a high point, such as at the base of a mountain, and used gravity with a carefully calculated slope to carry the water so that the channel surfaced close to an agricultural plain. AlUla's extensive network of qanats made it possible to farm large strips of land. Such major engineering projects, involving immense collective effort, suggest that improving water supplies was a priority. It's universally recognized today that modern AlUla is still verdant (青翠的) and bountiful ， producing 90，000 tons of dates each year. But ... ...
