Pakistan’s catastrophic floods this year overshadowed the Indus River’s pivotal role in irrigating the country’s farmland and generating its electricity. But even as river levees tumbled, engineers were completing plans to enlarge generating capacity of the Indus’ mighty Tarbela dam by 27% and to build the even larger Diamer Basha hydro project farther upstream. Photo: Courtesy Mott Macdonald Group Tarbela siltation prompted power planners to site a second dam upstream. Diamer Basha will be sited more than 300 kilometers upriver of Tarbela but will, nevertheless, boost the lower plant’s output by reducing sedimentation. Since Tarbela’s completion some 36 years ago,
Arch dams, classically curved monoliths situated in narrow valleys, are not as common as other types of dams, such as embankment dams and gravity dams. ENR takes a look at some of the biggest arch dams in the world, both completed and under construction.