In the pages of Erosion Control and online, we’ve often debated the pros and cons of dam removal. Demolishing outdated ones—many of which are a century or more old and in danger of collapse, and some of which have outlived their original purpose—can return a river to something closer to its natural state, improving habitat and allowing fish passage. On the other hand, the silt and sediment that has built up behind a decades-old dam can wreak havoc on the downstream environment if it’s released all at once when a dam is removed.
A group working in Dubai has found, if not a complete answer to the dam problem, at least a use for the silt. The region’s reservoirs tend to silt up quickly and lose water-holding capacity. The startup company Afforest for Future is dredging the sediment and spreading it over sandy soil to create instant farmland. Satellite imagery can help determine which dams and reservoirs have accumulated the most silt.
Before it’s spread, the silt from the reservoirs behind the dams is amended, both to improve its texture and to add nutrients. The head of the company, Vesela Tanaskovic, developed and tested the process at the Technical University of Vienna and at NASA’s Ames Research Center. She says the process takes only one day, and then the silt is ready to distribute and be planted with trees, crops, or both.
As this article on the process points out, worldwide 23 hectares of arable land are lost each minute, amounting to 12 million hectares a year, because of drought, climate change, overgrazing, and various other causes. The area around Dubai, where the pilot project is taking place, has been desert for more than 11,000 years; if the process works here, it should work just about anywhere—provided, of course, that water is available to keep the plants growing. The article also covers some similar efforts around the world—from tree-planting in Mongolia to water-retaining materials in Norway and China—to help slow or reverse desertification.