By Peter Bosshard
The Huffington Post, June 18, 2010
www.huffingtonpost.com/peter-bosshard/the-forgotten-downstream_b_616796.html?view=print
An estimated 472 million people have likely been negatively impacted by
the downstream impacts of large dams. This is the main finding of a
scientific study which was just published by a group of eminent global
freshwater experts. The study documents the impacts which dams have had on
some of the world's most productive ecosystems, and recommend measures
which can prevent the further loss of floodplains that sustain unique
ecosystems and millions of people.
In the 1970s, Kharochan was a bustling town in Pakistan's Indus Delta. The
local farmers grew rice, peas, coconuts, mango and guava on their rich
soils. From the nearby harbor Sokhi Bandar -- the "Port of the Prosperous"
-- traders exported silk, rice and wood. When I visited in 2006, no traces
of prosperity were left in Kharochan. The port had been swallowed by the
sea, and the groundwater had become saline in large parts of the delta. A
white crust of salt covered the earth, and turned Kharochan's fertile
fields into parched land. More than half the region's population lived
below the poverty line, and thousands had left their homes for the
sprawling city of Karachi.
The Indus Delta has not been struck by a natural disaster. Its plight is
human-made. The Indus -- the world's tenth-largest river in terms of the
water it carries -- has been plugged by 19 dams and is being sucked dry by
43 large canals. The Indus no longer reaches the sea in most years, and its
sediments no longer replenish the delta. As a consequence, Pakistani
experts told me, 8,800 square kilometers of agricultural land have been
lost to the sea since dam building began.
The fate of the people who are being displaced for dams in places like
Pakistan, China, Brazil and India have haunted the public imagination for
decades. In contrast, the people and ecosystems who suffer under the
downstream impacts of large dams have often been ignored. A new scientific
paper in the academic online journal Water Alternatives provides an
in-depth look at the downstream impacts of large dams. The paper was
prepared by a group of researchers around Brian Richter and Carmen Revenga
of The Nature Conservancy's Global Freshwater Program, Sandra Postel of the
Global Water Policy Project, Thayer Scudder, a former member of the World
Commission on Dams, and Bernhard Lehner of McGill University.
Rivers, floodplains and deltas feed hundreds of millions of people by
sustaining fisheries, flood recession agriculture, and dry-season grazing
land. As the Millennium Ecosystem Assessment has found, floodplains are
among the most productive ecosystems on Earth. Rivers and floodplains also
nurture riverine and mangrove forests, recharge groundwater resources, and
provide the silt which protects deltas from being eaten away by coastal
erosion.
Today about 50,000 large dams block the arteries of the planet. They have
stopped fish from migrating, withheld nutrients from floodplain ecosystems
and agriculture, dried up wells and riverine forests, and left deltas
exposed to saltwater intrusion and erosion. The new paper presents numerous
case studies for these impacts. After the Tucurui Dam was built on the
Tocantins in Brazil, the fish catch immediately fell by 60 percent,
affecting tens of thousands of people. The fish yields in the wetlands of
Cameroon's Logone River fell by 90 percent after the Maga Dam was built.
Similar impacts have been documented for dams on Ghana's Volta, Thailand's
Mun and West Africa's Senegal River.
An estimated 40-80 million people have been displaced by dams. Reservoir
refugees are usually entitled to compensation for their losses. Most
downstream-impacted people don't have any such rights. The people who were
displaced by the World Bank's Tarbela Dam in Pakistan received new homes on
the banks of the reservoir and financial compensation. Yet the people who
lost their homes to the sea because of the dam's downstream impacts cannot
claim any compensation under Pakistan's laws or the World Bank's safeguard
policies. The Bank argues that the degradation of the Indus Delta is "part
of the bargain struck in order to support large numbers of people in the
Indus Basin." In other words, some people have to suffer so that others can
prosper.
Dams contribute to about 12-16 percent of the world's food production, and
generate 19 percent of the world's electricity. As in the case of Pakistan,
dam builders have often maintained that these benefits compensate for the
losses of downstream communities. Yet downstream impacts can extend far
beyond the reach of reservoir fisheries and irrigation, and can outweigh
the benefits of dams. The new study presents case studies for this. While
large, deep reservoirs yield an average of 10-50 kilogram fish per hectare
and year, floodplain fisheries yield an average of 200-2000 kilogram per
hectare and year. Scientific studies have also found that even without
considering the cost of building a dam, the economic value of floodplains
may be higher than the value of irrigated land.
As part of their research, the authors of the new paper created a database
of case studies about the downstream impacts of dams. Their database covers
more than 120 rivers in at least 70 countries. The researchers created a
separate database of all rivers which have at least one tenth of their
annual water discharge stored by the world's 7,000 largest dams. By using a
geographic information system, they calculated that the downstream impacts
of dams on these rivers have probably negatively affected at least 472
million people. Of these, 400 million live in Asia. By cross-referencing
their calculation with specific case studies, they found that their
estimate is likely to be conservative.
Richter and his co-authors conclude "that dam development projects aimed
at reducing poverty or improving economic opportunities are benefiting many
but are also deepening poverty and hunger for others. The failure to
adequately account for these impacts precludes an honest rendering of the
net costs and benefits of dams." They argue that "a sizeable proportion of
the human population is being fed by the natural productivity of river
ecosystems," and "that it does not make sense to continue to damage these
natural life-support systems when far less destructive approaches to dam
development are readily available."
The authors put forward a series of practical recommendations that could
help to take downstream impacts of large dams into account. They make the
case for an integrated planning approach to whole river basins, to prevent
dams from being built in the wrong places. Integrated river basin planning
takes social, environmental and economic costs and benefits into account,
and includes the evaluation of rivers' current benefits through
participatory assessments. The authors also call for dam design and
operational plans which strike an optimum balance between economic, social
and environmental benefits -- for example, through providing adequate
environmental flows -- and which are continuously monitored and adapted.
A successful example for the authors' approach is the relicensing
agreement between a power company, the Penobscot Indian Nation and
environmental NGOs regarding hydropower plants on the Penobscot River in
the Northeastern US. Under this agreement, two dams will be removed and the
fish passage on another dam was improved. Even so, the total power
generation from the dams on the river will be maintained or slightly
increased through the rehabilitation of the remaining power plants.
From a personal perspective I will add that it is no longer acceptable to
sacrifice the interests of one population group for the benefit of another
in a supposed "bargain" struck by powerful elites. Like other affected
people, downstream-impacted communities should have the right to
participate in the decision-making process over projects that affect them,
and should be entitled to full compensation of their losses if indeed a dam
is built. If all costs and benefits of water and energy options are
considered in a balanced assessment, less destructive solutions than large
dams will be found in many cases.
Brian D. Richter, Sandra Postel, Carmen Revenga, Thayer Scudder, Bernhard
Lehner, Allegra Churchill, Morgan Chow: Lost in development's shadow, The
downstream human consequences of dams, in: Water Alternatives 3(2), June
2010: pp. 14-42
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