67
Along this basic principle, we will give an overview of large dams that have
emerged worldwide during recent years. We will then focus on the costs and benefi ts of MWEPs with special attention to the often neglected values of ecosystem
services and distributional effects for society.
5.2 The Emergence of Major Water Engineering Projects
Worldwide: Large Dams on the Advance
Hydropower production is a very well-established technique of the electricity system. Worldwide, out of 37,600 dams higher than 15 m more than 8,600 dams for
hydropower generation are in operation, contributing about 20 % to the global electricity production. A period of intense dam building has been observed from the
1930s to the 1970s in North America, Japan and Western Europe. Major hydropower dam building in industrialised countries has now slowed, partly because the
best sites have already been exploited within these countries, but also due to a
greater understanding of the often unexpected social, economic, and environmental
costs (Poff and Hart 2002 ; Lehner et al. 2011 ; ICOLD 2014 ).
Large dams mean high risks. Indeed, on average, the construction of large dams took
much longer than planned and the expenses were twice as high as calculated. Furthermore,
social and ecological costs were often not included because they are diffi cult to be calculated. Therefore, large dams, as well as other large infrastructure projects, are considered economically ineffective and should not be favoured (Ansar et al. 2014 ).
Despite the expected risks, we actually face an unprecedented boom in hydropower dam construction worldwide, primarily in developing countries and emerging economies (Zarfl et al. 2015 , Fig. 5.1 ). While the expected construction of
more than 3700 major dams may almost double the global electricity production
from hydropower, it also may reduce the number of the last remaining large freefl owing rivers by about 20 %, in particular in South America. Many of the future
dams are planned in areas with an exceptional high freshwater biodiversity. The
Mekong, Amazon, and Congo basins are biodiversity hot spots that together contain about 1/5 of the global freshwater fi sh diversity. In particular, these basins
will be heavily impacted by future hydropower development. Similarly, the
Balkan area and Turkey face a major boom in dam construction; both regions are
major centres of freshwater biodiversity.
Dam construction is becoming more and more a global business. A recent analysis on involved investors demonstrates that an increasing number of dam projects
are fi nanced by internationally operating companies (Zarfl et al. 2015 ). The construction costs of the 3700 dams planned or under construction may amount up to
USD 2 trillion within the coming 10–20 years, excluding running and maintenance
costs. Considering the fact that the costs and the construction timelines are systematically underestimated, we may expect costs that are at least twice as high. This is
in line with Ansar et al. ( 2014 ) who fi nd a mean cost overrun of 96 % in the construction of dams. At the same time, there are doubts that the projected increase in
hydropower production will close the so-called electricity gap, i.e. providing access
5 Neglected Values of Major Water Engineering Projects…
Along this basic principle, we will give an overview of large dams that have
emerged worldwide during recent years. We will then focus on the costs and benefi ts of MWEPs with special attention to the often neglected values of ecosystem
services and distributional effects for society.
5.2 The Emergence of Major Water Engineering Projects
Worldwide: Large Dams on the Advance
Hydropower production is a very well-established technique of the electricity system. Worldwide, out of 37,600 dams higher than 15 m more than 8,600 dams for
hydropower generation are in operation, contributing about 20 % to the global electricity production. A period of intense dam building has been observed from the
1930s to the 1970s in North America, Japan and Western Europe. Major hydropower dam building in industrialised countries has now slowed, partly because the
best sites have already been exploited within these countries, but also due to a
greater understanding of the often unexpected social, economic, and environmental
costs (Poff and Hart 2002 ; Lehner et al. 2011 ; ICOLD 2014 ).
Large dams mean high risks. Indeed, on average, the construction of large dams took
much longer than planned and the expenses were twice as high as calculated. Furthermore,
social and ecological costs were often not included because they are diffi cult to be calculated. Therefore, large dams, as well as other large infrastructure projects, are considered economically ineffective and should not be favoured (Ansar et al. 2014 ).
Despite the expected risks, we actually face an unprecedented boom in hydropower dam construction worldwide, primarily in developing countries and emerging economies (Zarfl et al. 2015 , Fig. 5.1 ). While the expected construction of
more than 3700 major dams may almost double the global electricity production
from hydropower, it also may reduce the number of the last remaining large freefl owing rivers by about 20 %, in particular in South America. Many of the future
dams are planned in areas with an exceptional high freshwater biodiversity. The
Mekong, Amazon, and Congo basins are biodiversity hot spots that together contain about 1/5 of the global freshwater fi sh diversity. In particular, these basins
will be heavily impacted by future hydropower development. Similarly, the
Balkan area and Turkey face a major boom in dam construction; both regions are
major centres of freshwater biodiversity.
Dam construction is becoming more and more a global business. A recent analysis on involved investors demonstrates that an increasing number of dam projects
are fi nanced by internationally operating companies (Zarfl et al. 2015 ). The construction costs of the 3700 dams planned or under construction may amount up to
USD 2 trillion within the coming 10–20 years, excluding running and maintenance
costs. Considering the fact that the costs and the construction timelines are systematically underestimated, we may expect costs that are at least twice as high. This is
in line with Ansar et al. ( 2014 ) who fi nd a mean cost overrun of 96 % in the construction of dams. At the same time, there are doubts that the projected increase in
hydropower production will close the so-called electricity gap, i.e. providing access
5 Neglected Values of Major Water Engineering Projects…