Large dam projects need better scientific evaluation
March 23rd, 2006
The environmental impacts of a new dam project on the Nile River in Sudan were not assessed properly. Such billion dollar projects should be evaluated independently in order to guarantee that their design and operation will be based on the best available scientific knowledge. This is the main conclusion in a recent report by researchers of Eawag, the Swiss Federal Institute of Aquatic Science and Technology in Switzerland, on the Merowe Dam Project – a n ew impoundment upstream of the Aswan High Dam on the main branch of the Nile. The 67 m high dam will submerge the fourth cataract of the Nile and produce peak electricity for the major cities in Sudan. The construction of the $ 1.2 billion dam is managed by Lahmeyer International (Germany), Alstom (France) is supplying electro-mechanic equipment; and ABB (Switzerland) is building transmission substations.
In their independent review the Eawag researchers conclude that the Merowe
dam will act as an important sediment sink and may accumulate as much as 130 Mio
tons of sediment annually. An effective concept for managing this sediment load
will be urgently needed to prolong the lifetime of the reservoir. Previous
experience with the Aswan High Dam indicates that water quality in the reservoir
and greenhouse gas emissions might become problems too if no adequate measures
will be taken. The detrimental effects of the dam on the biodiversity of the
fish community have been underestimated. Finally, the dramatic downstream water
level fluctuations due to the daily peak operation of the power plant should be
mitigated adequately in order to protect the riparian population, the sensitive
river banks and their aquatic life.
In their general conclusions the Eawag experts call for improving the operational policies, when the environmental impacts of large dam projects are analyzed: Such important assessments should be based on the latest scientific insights, they should be reviewed by independent experts and be available to the general public.
Independent Review, Eawag [pdf, 914 KB], short version [pdf, 193 KB]
Article in Nature [pdf, 491 KB]