58
basins are among the moderately fragmented river systems (Nilsson et al. 2005 ).
This means that these additional huge hydropower dams might change the fragmentation degree. There are also basins that have been classifi ed as not fragmented so
far that will face an increase in fragmentation, e.g. the Salween basin in Asia with
11 hydropower dams planned. Fragmentation leads to habitat destruction and prevents migration of aquatic organisms which might result in a decrease of biodiversity. In addition, hydropower dam operation will change discharge patterns, transport
of sediments and water temperature.
For some of the “smaller” very large dams (1,000–2,000 MW) data on the size of
the planned reservoir is known, which ranges up to 1,230 km
2 for the Mupata
George in the Zambesi basin. This exceeds the size of Lake Yssel in the Netherlands
and just indicates the area that might be required for huge hydropower dam constructions. One of the largest reservoirs by surface area, Lake Volta in Ghana, is
fl ooding more than 8,500 km
2 . This does not only affect the environment like fl ooding of terrestrial habitats, but also has social impacts due to the required relocation
of the residential human population.
4.2.4 Large-Scale Restoration Projects
While major investments in new water redistribution and hydropower projects are
underway across the emerging economies, governments throughout North America,
Europe and Australia are devoting increasing efforts into removing or heavily modifying the major water infrastructure projects of the last century. Increasing recognition of the environmental harm to fi sheries and biodiversity caused by hard
infrastructure has spurred growing interest in dam removal and channel reconfi guration efforts to restore historic river structures and ecological processes.
As an inevitable consequence of increased environmental degradation and anticipated future environmental change, the demand for ecosystem restoration is rapidly
increasing. “Develop now, clean-up later” has been the motto of many rapid emerging economies. The clean-up phase will be expensive and will take decades to centuries in most cases. Indeed, we probably are not able to imagine the future costs of
ecosystem restoration, the damage in respect to loss of ecosystem services and the
need to install extremely expensive engineering measures to compensate for the
impacts of the past management decisions.
One of the most ambitious projects is the restoration of the Mississippi River
Delta , following hurricane Katrina. It is planned to run for 50 years and estimated
to cost between USD 500 million and USD 1.5 billion per year. And it will only stop
future land loss, and not lead to the full recovery of the vast amount of wetlands
already gone (Giosan et al. 2014 ). A recent study by Batker et al. ( 2010 ) shows that
the investment to sustainably restore the Mississippi River Delta would return several time more of values in respect to provided ecosystem services. Indeed, the
Mississippi River Delta Ecosystems provide economically valuable services,
including hurricane storm protection, water supply, climate stability, food, furs,
K. Tockner et al.
basins are among the moderately fragmented river systems (Nilsson et al. 2005 ).
This means that these additional huge hydropower dams might change the fragmentation degree. There are also basins that have been classifi ed as not fragmented so
far that will face an increase in fragmentation, e.g. the Salween basin in Asia with
11 hydropower dams planned. Fragmentation leads to habitat destruction and prevents migration of aquatic organisms which might result in a decrease of biodiversity. In addition, hydropower dam operation will change discharge patterns, transport
of sediments and water temperature.
For some of the “smaller” very large dams (1,000–2,000 MW) data on the size of
the planned reservoir is known, which ranges up to 1,230 km
2 for the Mupata
George in the Zambesi basin. This exceeds the size of Lake Yssel in the Netherlands
and just indicates the area that might be required for huge hydropower dam constructions. One of the largest reservoirs by surface area, Lake Volta in Ghana, is
fl ooding more than 8,500 km
2 . This does not only affect the environment like fl ooding of terrestrial habitats, but also has social impacts due to the required relocation
of the residential human population.
4.2.4 Large-Scale Restoration Projects
While major investments in new water redistribution and hydropower projects are
underway across the emerging economies, governments throughout North America,
Europe and Australia are devoting increasing efforts into removing or heavily modifying the major water infrastructure projects of the last century. Increasing recognition of the environmental harm to fi sheries and biodiversity caused by hard
infrastructure has spurred growing interest in dam removal and channel reconfi guration efforts to restore historic river structures and ecological processes.
As an inevitable consequence of increased environmental degradation and anticipated future environmental change, the demand for ecosystem restoration is rapidly
increasing. “Develop now, clean-up later” has been the motto of many rapid emerging economies. The clean-up phase will be expensive and will take decades to centuries in most cases. Indeed, we probably are not able to imagine the future costs of
ecosystem restoration, the damage in respect to loss of ecosystem services and the
need to install extremely expensive engineering measures to compensate for the
impacts of the past management decisions.
One of the most ambitious projects is the restoration of the Mississippi River
Delta , following hurricane Katrina. It is planned to run for 50 years and estimated
to cost between USD 500 million and USD 1.5 billion per year. And it will only stop
future land loss, and not lead to the full recovery of the vast amount of wetlands
already gone (Giosan et al. 2014 ). A recent study by Batker et al. ( 2010 ) shows that
the investment to sustainably restore the Mississippi River Delta would return several time more of values in respect to provided ecosystem services. Indeed, the
Mississippi River Delta Ecosystems provide economically valuable services,
including hurricane storm protection, water supply, climate stability, food, furs,
K. Tockner et al.