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5.3.2 Ecological Trade-Offs
Natural biogeochemical processes and diverse communities of aquatic biota regulate freshwater quantity and quality in ways that are not suffi ciently acknowledged nor appreciated
by the water resources management community (Arthington and Naiman 2010 , p. 1).
In a majority of MWEPs, environmental impacts and consequences for ecosystem services and human well-being are underestimated (World Commission on
Dams 2000 ; Russi et al. 2013 ). The Three Gorges Project (Gleick 2009 ; Fu et al.
2010 ) or the Aral Sea basin (Cai et al. 2003 ) are examples of large scale environmental impacts that have been underestimated at early planning stages. Ecological
costs are diffi cult to estimate since they partly become apparent only in the longer
run. Nevertheless, it has become obvious (especially in the Aral Sea basin case) that
these ecological impacts have destroyed an entire landscape, with severe consequences not only for environmental but also for human health.
The conceptual framework of ecosystem services accounts for four categories of
services that people derive from ecosystem functions (Millennium Ecosystem
Assessment 2005a , b ; Russi et al. 2013 ).
• Provisioning services are water for consumptive uses (drinking water, irrigation), nonconsumptive uses (hydropower, navigation), and food, medicine, and genetic resources.
• Regulating services are maintenance by water (fi ltration), climate (carbon
sequestration), or natural hazard regulation (fl ood and erosion).
• Cultural services are nonmaterial benefi ts such as recreation, learning, cultural
heritage, tourism, or existence values.
• Supporting services are those services required to maintain the overall functioning of ecosystems such as primary production and ecosystem resilience that
often have long-term effects on people’s benefi ts (Russi et al. 2013 ).
While in the past provisioning services have regularly been captured by economic analysis, it is the long-term impacts on ecosystems that have long been
neglected in economic assessment methods for costs and benefi ts . Nevertheless,
these ecosystem services are important for people’s welfare. The Millennium
Ecosystem Assessment ( 2005a ) clearly showed how much people’s well-being
depends on functioning ecosystems and their services, and that many ecosystems
are not managed sustainably. Management decisions that omit effects on the functioning of ecosystems and losses in their (provisioning, regulating, cultural, and
supporting) services are therefore incomplete and likely have deteriorating consequences for ecosystem service provision and human well-being.
One illustrative example might be the greenhouse gas emissions from creating
large reservoirs. While hydropower generally is considered a renewable source of
energy, newly created reservoirs emit substantial amounts of greenhouse gases
due to organic matter decomposition (World Commission on Dams 2000 ;
Fearnside 2002 ; Mäkinen and Khan 2010 ). Emission rates are highly site specifi c
and depend, for example, on reservoir age and latitude (Barros et al. 2011 ).
Indeed, emissions from reservoirs may even outnumber the emissions by a comB. Hansjürgens et al.
5.3.2 Ecological Trade-Offs
Natural biogeochemical processes and diverse communities of aquatic biota regulate freshwater quantity and quality in ways that are not suffi ciently acknowledged nor appreciated
by the water resources management community (Arthington and Naiman 2010 , p. 1).
In a majority of MWEPs, environmental impacts and consequences for ecosystem services and human well-being are underestimated (World Commission on
Dams 2000 ; Russi et al. 2013 ). The Three Gorges Project (Gleick 2009 ; Fu et al.
2010 ) or the Aral Sea basin (Cai et al. 2003 ) are examples of large scale environmental impacts that have been underestimated at early planning stages. Ecological
costs are diffi cult to estimate since they partly become apparent only in the longer
run. Nevertheless, it has become obvious (especially in the Aral Sea basin case) that
these ecological impacts have destroyed an entire landscape, with severe consequences not only for environmental but also for human health.
The conceptual framework of ecosystem services accounts for four categories of
services that people derive from ecosystem functions (Millennium Ecosystem
Assessment 2005a , b ; Russi et al. 2013 ).
• Provisioning services are water for consumptive uses (drinking water, irrigation), nonconsumptive uses (hydropower, navigation), and food, medicine, and genetic resources.
• Regulating services are maintenance by water (fi ltration), climate (carbon
sequestration), or natural hazard regulation (fl ood and erosion).
• Cultural services are nonmaterial benefi ts such as recreation, learning, cultural
heritage, tourism, or existence values.
• Supporting services are those services required to maintain the overall functioning of ecosystems such as primary production and ecosystem resilience that
often have long-term effects on people’s benefi ts (Russi et al. 2013 ).
While in the past provisioning services have regularly been captured by economic analysis, it is the long-term impacts on ecosystems that have long been
neglected in economic assessment methods for costs and benefi ts . Nevertheless,
these ecosystem services are important for people’s welfare. The Millennium
Ecosystem Assessment ( 2005a ) clearly showed how much people’s well-being
depends on functioning ecosystems and their services, and that many ecosystems
are not managed sustainably. Management decisions that omit effects on the functioning of ecosystems and losses in their (provisioning, regulating, cultural, and
supporting) services are therefore incomplete and likely have deteriorating consequences for ecosystem service provision and human well-being.
One illustrative example might be the greenhouse gas emissions from creating
large reservoirs. While hydropower generally is considered a renewable source of
energy, newly created reservoirs emit substantial amounts of greenhouse gases
due to organic matter decomposition (World Commission on Dams 2000 ;
Fearnside 2002 ; Mäkinen and Khan 2010 ). Emission rates are highly site specifi c
and depend, for example, on reservoir age and latitude (Barros et al. 2011 ).
Indeed, emissions from reservoirs may even outnumber the emissions by a comB. Hansjürgens et al.