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rivers in arid regions) have to be adapted so
as to concentrate on large-scale processes, such
as sediment dynamics and floodplain connection,
rather than indicator species and their habitat
requirements.
In the Ganga, environmental considerations
centred on the quantity and quality of water in
order to facilitate spiritual activities such as bathing
and purification from riverside ghats, but also
demonstrated that these requirements matched
well with the requirements for key species such as
river dolphins. Flows required in order to ensure
that water reaches waist height at the ghats also
provide the mosaic of deep pools and shallow
feeding areas preferred by the dolphins. It is
gratifying, but perhaps not surprising, to find that
traditional human rituals, as well as riverine flora
and fauna, are adapted to the natural diversity of
river flows.
Environmental flows are being implemented
in an increasing number of rivers - the Senqu
in Lesotho, the Berg in south-western South
Africa, the Snowy and Murray Rivers in Eastern
Australia, the Savannah River in Georgia and the
Willamette in Oregon, and the Yellow River in
China, amongst others (Hirji and Davis, 2009).
Many other countries are indicating a readiness
to apply environmental flows. Such flows cannot
be expected to solve all river related problems.
Most water quality problems should be dealt with
at source; increased sedimentation should usually
be addressed by improving land-use practices. Loss
of riparian vegetation is often a result of over-
grazing rather than flow problems. The recognition
of which problems can (and should) be dealt
with by adjusting flow regimes is an integral part
of the environmental flows assessment process,
and is addressed in the South African Water
Act 1998 by distinguishing between 'Resource
Directed Measures' such as the 'Ecological Reserve',
and 'Source Directed Controls' such as improved
sewage treatment methods.
The assessment and implementation of
environmental flows is proving to be a successful
and pragmatic aspect of river conservation,
restoration and IWRM in many parts of the world,
and is an excellent example of the progress that
has been made over the past two decades. The
four principles of IWRM, based on Lenton and
Muller (2009), and quoted in the section above
on the development and application of IWRM, are
integral to the success of environmental flows -
infrastructure to control flows and water demand;
a strong enabling environment and legislative
framework; institutional and stakeholder capacity;
and a sound understanding of the components,
processes and functions of natural water systems,
coupled with an effective monitoring system.
It is not that these ideas and research did not
exist before 1990, but that continued efforts
at integrated management and prioritizing
sustainability in water resource planning have
begun to pay dividends.
Acknowledgements
This chapter draws on the work of a large
number of scientists and conservationists. I am
particularly grateful to the WWF staff in the
UK and East African offices for the opportunity
to work with them on beautiful rivers. Special
gratitude and respect to Phil Boon for his
extraordinary achievement in organizing both the
York conferences, 20 years apart, and to the rest
of his conference team for an excellent and useful
event in 2010.
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