ABC Radio,“RN”, 9 May 2019:
The first global
assessment of the ecological health of the world's "wild" rivers has
found only about one third of the longest rivers are still free-flowing.
The report warns the
disruption is harming ecosystems, with 3,700 new large dams either under
construction, or planned.
Gill,Gunter et al,
(2019) Mapping the world’s free-flowing rivers
ABSTRACT
Free-flowing
rivers (FFRs) support diverse, complex and dynamic ecosystems globally,
providing important societal and economic services. Infrastructure development
threatens the ecosystem processes, biodiversity and services that these rivers
support. Here we assess the connectivity status of 12 million kilometres of
rivers globally and identify those that remain free-flowing in their entire
length. Only 37 per cent of rivers longer than 1,000 kilometres remain
free-flowing over their entire length and 23 per cent flow uninterrupted to the
ocean. Very long FFRs are largely restricted to remote regions of the Arctic
and of the Amazon and Congo basins. In densely populated areas only few very
long rivers remain free-flowing, such as the Irrawaddy and Salween. Dams and
reservoirs and their up- and downstream propagation of fragmentation and flow
regulation are the leading contributors to the loss of river connectivity. By
applying a new method to quantify riverine connectivity and map FFRs, we
provide a foundation for concerted global and national strategies to maintain
or restore them.
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