Sediment trapped in dams can significantly impair the water storage capacity of the infrastructure. The effect, in the coming decades, will be that between 23 and 28 percent of the world’s major dams are likely to lose their potential. A study published in the journal Sounded the Alarm sustainability, led by scientists from UNC’s Canadian Institute of Water, Environment and Health and McGill University in Montreal. The team led Domina Pereiraestimated the effect of the presence of sediment in 47,403 dams in 150 countries, taking into account approximately 50,000 buildings.
According to the authors, there could be a loss of 23-28 percent of the original storage capacity by 2050. At the same time, experts report that the largest losses in the world will occur in the United Kingdom, Panama, Ireland, Japan and the Seychelles, where it is estimated that storage capacities will decrease by between 35 and 50 percent compared to the original conditions. In contrast, the five least affected countries will be Bhutan, Cambodia, Ethiopia, Guinea and Niger, associated with declines of less than 15 percent.
“This reduction – Pereira says – It will test many aspects of national economies, including irrigation, power generation, and water supply. New dams under construction or planned will not compensate for storage losses due to sedimentation. Our work highlights sedimentation issues that threaten the sustainability of future water suppliesOf the 6,651 large European dams, scientists say, there could be a loss of 21 percent by 2030 and 28 percent by 2050. In Italy, a decline of more than 25 percent is expected.
To solve this problem, scientists propose several solutions, highlighting their strengths and drawbacks. In particular, scraping can be very expensive and only temporary. On the other hand, sediment leaching is more attractive from a financial point of view, but can cause significant negative effects downstream. Bypass, a technology that diverts flow downstream through a separate channel to deal with extreme events and floods, can reduce settling risks by 80-90 percent.
Improving the dam’s height could be a viable alternative. However, to determine the best strategy for each structure, an in-depth analysis of the characteristics of each dam and a careful assessment of the structural strength of the infrastructure is necessary. “Our results – Pereira concludes – It should be interpreted by the judicial authorities taking into account local characteristics and factors. What is more important to stress is the general alarming extent of water storage loss due to sedimentation. This adds to the list of global water development issues that we must firmly address.”
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