126
definitions exist for a stream mitigation unit: some rely on quantity (e.g., linear
length of stream), whereas others use minimally specified measures of quality (e.g.,
maintenance of cross-sectional form without substantial erosion or deposition over
a specified time period). Third, existing stream mitigation projects have not required
aquatic ecological assessment or monitoring, which can allow practitioners to
employ only the most basic physical measures of a stream’s form, rather than an
integrative measure of stream function. Finally, if fully functional stream ecosystems are being degraded under the assumption that there is no net loss because of
mitigation elsewhere, this is misleading. Even the most well designed and thorough
restoration projects commonly do not fully restore stream ecosystems and local
restoration projects do not compensate for basin-scale changes in factors such as
land use (Bernhardt and Palmer 2011).
The challenge of protecting and restoring river ecosystems is enormous in a
world where human population and energy and resource consumption are soaring,
especially if that world is at least partly controlled by people who do not recognize
the importance of maintaining functional river ecosystems. This challenge is common to any form of ecosystem protection and restoration or efforts to achieve ecological sustainability. Four examples of river basin management and restoration
programs from Europe and North America illustrate efforts to address this
challenge.
As noted previously, the EU Water Framework Directive mandates international,
coordinated river basin management. The Danube River drainage basin includes the
territories of 18 nations and has thus needed at least some level of international
cooperation for many decades. As reviewed in Nachtnebel (2000), a basin-wide
agreement governing navigation was developed after the Second World War, but
other forms of cooperation prior to the 1990s were bilateral agreements between
neighboring countries. The Environmental Programme for the Danube River Basin
was conceived in 1991 as a means of addressing problems that included high nutrient loads; changes in flow and sediment transport regimes resulting from numerous
dams; water pollution; and competition for water among consumptive users. The
environmental action plan included priority actions related to water quality and river
restoration (Botterweg and Rodda 1999; Bloesch and Sieber 2003), as well as studies in preparation for agreement on new regulations within the drainage basin. The
first Danube River basin management plan was agreed on in 2009 (Sommerwerk
et al. 2010). Progress thus far has included reducing nitrogen loads entering the
Black Sea from the Danube basin (Balana et al. 2011) and generally improving
water quality in the upper drainage basin (Wohl 2011). The management plan has
also established a basin-wide monitoring network and restored connectivity and
complexity along some floodplain reaches of the Danube and its major tributaries
(Hohensinner et al. 2005).
A much smaller-scale example of river restoration that includes complexity and
connectivity comes from the Mareiterbach, or Rio Ridanna, in the South Tyrol
region of Italy. The Mareiterbach drains 212 km
2
of glaciated, mountainous terrain
underlain by slate, which produces high sediment yields in this region of steep terrain and relatively wet climate (mean annual precipitation of ~800 mm) (Moritsch
4 Toward Sustainable Rivers and Water Resources
definitions exist for a stream mitigation unit: some rely on quantity (e.g., linear
length of stream), whereas others use minimally specified measures of quality (e.g.,
maintenance of cross-sectional form without substantial erosion or deposition over
a specified time period). Third, existing stream mitigation projects have not required
aquatic ecological assessment or monitoring, which can allow practitioners to
employ only the most basic physical measures of a stream’s form, rather than an
integrative measure of stream function. Finally, if fully functional stream ecosystems are being degraded under the assumption that there is no net loss because of
mitigation elsewhere, this is misleading. Even the most well designed and thorough
restoration projects commonly do not fully restore stream ecosystems and local
restoration projects do not compensate for basin-scale changes in factors such as
land use (Bernhardt and Palmer 2011).
The challenge of protecting and restoring river ecosystems is enormous in a
world where human population and energy and resource consumption are soaring,
especially if that world is at least partly controlled by people who do not recognize
the importance of maintaining functional river ecosystems. This challenge is common to any form of ecosystem protection and restoration or efforts to achieve ecological sustainability. Four examples of river basin management and restoration
programs from Europe and North America illustrate efforts to address this
challenge.
As noted previously, the EU Water Framework Directive mandates international,
coordinated river basin management. The Danube River drainage basin includes the
territories of 18 nations and has thus needed at least some level of international
cooperation for many decades. As reviewed in Nachtnebel (2000), a basin-wide
agreement governing navigation was developed after the Second World War, but
other forms of cooperation prior to the 1990s were bilateral agreements between
neighboring countries. The Environmental Programme for the Danube River Basin
was conceived in 1991 as a means of addressing problems that included high nutrient loads; changes in flow and sediment transport regimes resulting from numerous
dams; water pollution; and competition for water among consumptive users. The
environmental action plan included priority actions related to water quality and river
restoration (Botterweg and Rodda 1999; Bloesch and Sieber 2003), as well as studies in preparation for agreement on new regulations within the drainage basin. The
first Danube River basin management plan was agreed on in 2009 (Sommerwerk
et al. 2010). Progress thus far has included reducing nitrogen loads entering the
Black Sea from the Danube basin (Balana et al. 2011) and generally improving
water quality in the upper drainage basin (Wohl 2011). The management plan has
also established a basin-wide monitoring network and restored connectivity and
complexity along some floodplain reaches of the Danube and its major tributaries
(Hohensinner et al. 2005).
A much smaller-scale example of river restoration that includes complexity and
connectivity comes from the Mareiterbach, or Rio Ridanna, in the South Tyrol
region of Italy. The Mareiterbach drains 212 km
2
of glaciated, mountainous terrain
underlain by slate, which produces high sediment yields in this region of steep terrain and relatively wet climate (mean annual precipitation of ~800 mm) (Moritsch
4 Toward Sustainable Rivers and Water Resources