Dams Report
Dams Report
Dams Report
on Life in Rivers
Submitted to the
World Commission on Dams
Prepared by
Biksham Gujja and Diwata Olalia Hunziker
April 2000
The Impact of Dams on Life in Rivers 2
The material and geographical designations in this report do not imply the
expression of any opinion whatsoever on the aprt of WWF concerning the legal
status of any country, territory, or area, or concerning the delimitation of its
frontiers or boundaries.
Published in April 2000 by WWF−World Wide Fund for Nature (formerly World
Wildlife Fund), Gland, Switzerland. Any reproduction in full or in part of this
publication must mentioned the title and credit the above-mentioned publisher as
the copyright owner.
April 2000
The Impact of Dams on Life in Rivers 4
Photo credits
A Research Report
Submitted to the World Commission on Dams
CONTRIBUTIONS
Our heartfelt thanks to the following colleagues and contributors without whom this paper
would not have been possible, and to those who have chosen to remain anonymous.
Robin Adell (WWF USA);Azwar (Indonesia); Arch. Guglielmo Blanzone (Italy); Alain
Cassani (Switzerland); Monica Chundama (WWF Zambia); Alberto Fernandez (WWF
Spain); Michelle Handley (WWF Australia); Liang Haitang (WWF China); Najam
Kurshid (WWF Pakistan); Roger Landivar (WWF Bolivia); Chiseche M. Mutale
(Zambia); Daniel Ngantou (WWF Cameroon); Bernadete Ribas Lange (WWF Brazil);
Gert Polet (Vietnam); Juan Carlos Riveros (WWF Peru); David Claudio Antonio
Scarpinella (Brazil); P.A. Brasil; Joanna Tang (WWF Malaysia); Seng Teak, WWF
Indochina (Cambodia); Antonio Tricarico (Italy); David Stone (Switzerland); Liang
Haitang (WWF China); Syed Najam Khurshid (Pakistan); Alexander Zinke (Austria)
Acknowledgements
We wish to thank Musonda Mumba and Amalia Romeo (WWF Freshwater Programme)
for their most valuable assistance in preparing this report.
The Impact of Dams on Life in Rivers 6
Contents
I. Introduction
II. Methodology
Annexes
References
List of tables
Boxes
I. Introduction
II. Methodology
A fact sheet (Annex 1) was developed and species. The impacts could be more
first sent to WWF's freshwater network, significant than we could possibly
who had the technical expertise in substantiate through the data received.
providing the information needed. Some
were able to provide information Information on a total of 91 dams
immediately, and others had to hire representing 30 countries were
consultants for various reasons (work received (Table 1). Pakistan provided
overload, need for additional research, etc.) data on 23 dams and barrages that
or gave names of contact persons. constitute the water resources
Considerable follow-up was required to development of the Indus River and
have the fact sheets submitted on time, and Spain enumerated information on
the deadline was extended many times in specific species threatened or
order to receive as many fact sheets as endangered in 19 dams. The
possible. information submitted by Pakistan
and Spain underscores the degree of
The data received through the fact sheets difficulty in obtaining data required
can be considered as primary first-hand on the dams. For dams in
1
information. They came in four languages: Bangladesh, Brazil , Egypt and
English, French, Spanish and Italian. The Namibia 2, the information (for which
majority was received from WWF network. no fact sheets were written) given in
As expected from primary sources, the Annex 2 was researched by the
information given revealed regional/cultural authors. Certain data given in the fact
influences and different levels of sheets mention only the number of
understanding of the subject. These could endemic species that have become
be mainly attributed to inadequate and/or extinct or have disappeared, or
lack of scientific data. Nevertheless, the endangered and threatened, without
data gathered represents sufficient evidence necessarily specifying the name of the
and geographical representation (e.g., species. Others contain information
Bangladesh, Bolivia, Brazil, Cambodia, limited to the first part of the fact
Cameroon, China, Namibia, Pakistan, sheet (physical and geographical
Slovakia, and USA) to produce a synopsis description, EIA that are not analyzed
of some of the major impacts of dam in this study). Altogether, the fact
operations on ecosystems and sheets are the product of the time and
effort that the various offices and
individuals, within the given technical
capabilities and deadlines.
1
Tucurui Dam.
2
Epupa Hydropower Dam.
The Impact of Dams on Life in Rivers 7
A. Dams
1. History of dams 3
th
construction early 20
century 4
Technologies to convert the energy of flowing
water into mechanical energy have a history
3 4
McCully, Silenced Rivers, pp. 12-17. http://www.nps.gov/olym/issues/isselwha2.htm
The Impact of Dams on Life in Rivers 10
5
WWF, A Place for Dams in the 20th Century, p. 4
The Impact of Dams on Life in Rivers 11
Dams have two main functions. The first head allow dams to generate electricity
is to store water to compensate for (hydropower provides nearly a fifth of the
fluctuations in river flow or in demand world's electricity); to supply water for
for water and energy. Storing water agriculture, industries and households; to
requires raising the level of the water control flooding; and to assist river
upstream to enable water to be diverted navigation by providing regular flows and
into a canal or to increase "hydraulic drowning rapids. Other reasons for
head" – the difference in height between building large dams include reservoir
the surface of a reservoir and the river fisheries and leisure activities such as
downstream. The creation of storage and boating (cf. column 4, Annex 2).
6
http://www.nps.gov/olym/issues/isselwha2.htm
The Impact of Dams on Life in Rivers 12
7 8
http://www.foe.co.uk/camps/biohab/bakunhom.htm WWF International, Changing Worlds, pp. 91-101.
The Impact of Dams on Life in Rivers 13
Plants
Provide a substrate for other organisms and food for many. Trees
are ecologically important in providing shade and organic debris
(leaves, fruit), structural elements (fallen trunks) and branches)
that enhance vertebrate diversity, in promoting bank stabilisation,
and in restricting or modulating floodwaters.
Invertebrates: protozoans
Found in virtually all freshwater habitats. Most abundant in waters
rich in organic matter, bacteria or algae. Feed on detritus, or
consume other microscopic organisms; many are parasitic on
algae, invertebrates or vertebrates.
Invertebrates: crustaceans
Include larger bottom-living species such as shrimps, crayfish and
crabs of lake margins, streams, alluvial forests and estuaries.
Invertebrates: insects
In rivers, streams and lake communities, grazing and predatory
aquatic insects dominate intermediate levels in food webs
(between microscopic producers, mainly algae, and fishes).
Vertebrates: fishes
More than half of all vertebrate species is fishes.
Fishes are the dominant organisms in terms of biomass, feeding
ecology and significance to humans, in virtually all aquatic
habitats, including freshwaters.
Vertebrates: birds
Top predators. Wetlands are often key feeding and staging areas
for migratory birds.
Vertebrates: mammals
Top predators, and grazers. Large species widely impacted by
habitat modification and hunting.
Box 1 mentions organisms that inhabit freshwater fishes and adjacent local
rivers, lakes and wetlands, which are home communities are sustained by them.
for most of freshwater biodiversity.
Representing only one percent, river water For example, inland wetlands of Africa are
is therefore a small part of an equally small reported to produce 1.5 metric tonnes of
and vulnerable ecosystem containing a fish annually and support one million
comparatively rich diversity of life. It is fishermen and about five million ancillary
so complex that "unlike forest ecosystems, fishery workers (Bernacsek, 1992). In
it is not possible to indicate biological Asia alone, more than two billion people
trends". WWF's Living Planet Report 1999 depend on wetland crops and fish as their
on freshwater ecosystems index − based on main staple and protein source (Ramsar,
102 freshwater species (available data 1998).
mostly North American and European)
including "... every mammal, bird, reptile, To illustrate further this richness, Table 3
amphibian, and fish species for which summarizes information available provided
time-series population data could be on some of the world's major watersheds.
obtained" − indicates that freshwater The number of fish species indicated
species have, on average, declined by includes estimates of the total number of
about 45 percent over a period of 30 years fish species present in each basin,
(Table 2). 9 excluding introduced species where
relevant information was available. The
The downward trend of fish species data has a significant error margin,
represents both considerable biological and reflecting different survey and reporting
economic significance. Other species methods, different taxonomies, date and
(birds and mammals) in the surrounding completeness of surveys, etc. (WCMC,
ecosystems depend on 1998).
10 0
80
60
40
20
0
19 70 19 75 19 80 19 85 19 90 19 95
9
WWF, Living Planet Report 1999, pp. 6-7.
The Impact of Dams on Life in Rivers 15
Every every river and the species it supports species and ecosystems. Irrigation waters, for
are both unique and complex at the same time. instance, whether from rivers or groundwater,
The same could be said of the effects every contain dissolved salts washed out of rocks
dam has on the river and its ecosystems. For and soils.
the downstream section alone, some of the
impacts the WWF discussion paper on dams Evaporation from reservoirs, canals and fields
outlined include the following: loss and increase the concentration of salts. When the
damage to freshwater habitats and species, water reaches crops, the roots absorb water but
reduction in silt due to filters and the dam leave in the soil most of the toxic salts. This
wall, changes in groundwater level, changes in has obvious severe consequence on the fields
flow, and waterlogging and salinity.10 of farmers whom, to prevent salinization,
apply more water to wash salts from the roots.
The major impacts of dams on ecosystems and However, this procedure increases the salinity
species considered in this report are outlined of groundwater and in the absence of good
in Table 4 below. According to the drainage, causes the water table to rise and
submissions, the most significant consequence through a chemical process, reaches the
of dams is the degradation or the destruction surface, eventually evaporating and leaving
of riverine ecosystems, isolating populations behind a crust of white crystals, thus
of species living up and downstream of the waterlogging the roots of the crops. Finally,
dam and cutting off migrations and other saline wastewater draining back into the river
species' movements. Almost all dams reduce progressively reduces downstream water
normal flooding, fragment ecosystems and quality for all users of water.11
isolate migratory species. The elimination of
biological benefits to a chain of organisms Notable wildlife species on the
Kafue flats are the semi-aquatic
may be the most damaging impact of dams.
Kafue lechwe (Kobus leche
kafuensis) and the Wattled crane
Initial analysis of information reveals that (Grus carunculatus), both of which
dams built for irrigation, flood control and have in the past been identified as
endangered by dam operations.
hydroelectric purposes are those that most
(Zambia, Itezhi-Itezhi Hydro-power
endanger and threatens Project)
10 11
WWF, A Place for Dams in the 20th Century, p.7-18. McCully, Silenced Rivers, pp. 168-169.
The Impact of Dams on Life in Rivers 17
Table 4.
Some of the major impacts of dams on ecosystems and species
Source: Factsheets
The Impact of Dams on Life in Rivers 18
12
Source: USA Fact sheets
The Impact of Dams on Life in Rivers 19
Source: Factsheets
The Impact of Dams on Life in Rivers 20
13
Brazil, Itaipú
The Impact of Dams on Life in Rivers 21
14
http://www.wcmc.org.uk/infoserv/countryp/vietnam/app4.html
#GAUR; http://www.ultimateungulate.com/gaur.html
The Impact of Dams on Life in Rivers 22
Species Dam
Gaur (Bos gaurus) Dong Nai No. 3 and Dong Nai No.
4 Combined Hydropower Project
Javan rhino (Rhinoceros Dong Nai No. 3 and Dong Nai No.
sondaicus annamiticus); White- 4 Combined Hydropower Project
winged wooden duck (Cairina (Vietnam)
scutulata)
Source: Factsheets
The Impact of Dams on Life in Rivers 23
Ganges dolphin
Hippo
tamus
(Platanista gangetica)
(Trich
echus
manat
us Javan rhino
latiros (Rhinoceros sondaicus annamiticus
tris)
15
cf. Annex 3
The Impact of Dams on Life in Rivers 24
16
Source: Fact sheets
The Impact of Dams on Life in Rivers 25
The vulnerability of a small but rich and The destructive cycle not only affects
complex ecosystem such as rivers is aquatic species but also adjacent forest
heightened by the construction of dams. and wetland ecosystems on which
Primary analysis of the raw data received from migratory birds are dependent, (cf.
WWF network submissions indicate that Siberian White Crane, China, Annex 2)
general dam operations lead to changes in and other mammals (cf. Javan
water (e.g., see China, Yangtze Three Gorges, rhino/Rhinoceros sondaicus annamiticus,
Annex 2) or could be Vietnam, Annex 2).
long-term leading to the The task to determine the
disappearance or extent of the impact of
extinction of species (cf. dams on the species is
Annex 2, USA, coho made more difficult by
salmon/ the lack of any scientific
Oncorryncchus kisutch). study both before and
after a dam is
The survival of river constructed.
dolphins, for example, is
by far the most graphic Some endemic fish
example of the impact of species were observed to
dams on river have developed morpho-
ecosystems. A number of potential problems logical changes (e.g., see Colorado squawfish/
caused by waterway obstruction has been Ptychocheilulucius, Annex 2) or have
identified: (a) fragmentation of populations increased and adapted to the changes in water
into genetically isolated subpopulations; (b) flows and temperatures (e.g. see Piranha,
reduction in fish prey due to blocked Brazil, Annex 2). Other marsh plants species
migratory routes; (c) less diversity and smaller have also been observed to increase and
biomass of prey in impoundments upstream of develop following dam operations in the USA
dams due to lowered nutrient availability; (d) (e.g., netleaf hackberry/Celtic reticulata),
downstream effects on prey caused by changes honey mosquito/Prosopis glandulosa).
in flow rate, sediment transport, and estuarine
salinity; (e) limited dispersal of dolphins
between river systems due to saline
encroachment in estuaries (Reeves and Photo: Ganges dolphin
Leatherwood, 1994). (Platanista gangetica)
The Impact of Dams on Life in Rivers 26
Bald Ibis
(Geronticus
17
calvus) Siberian White Crane
(Grus leucogeranus)
18
Atlantic Sturgeon
19
(Acipenser oxyrrhynchus)
Pedder Galaxias
20
(Galaxias pedderensis )
18
Photo taken from Partnership for a living Yangtze:
Joining hands for Better Future, WWF China.
19
http://www.dnr.cornell.edu/Sarep/fish/
17 Acipenseidae/atlsturg.html
http://perso.club-internet.fr/alfosse/
20
Threskiornithid.html http://www.parks.tas.gov.au/esl/pedder.html
The Impact of Dams on Life in Rivers 27
22
IUCN Red List Plants Mammals Fish and Birds TOTAL
21
Categories Amphibians
EX - - - -
EW - - - -
Ex/E - - - -
CR - 1 1 1 3
EN 2 5 3 3 13
VU 3 11 3 7 24
23
R - 2 3 - 5
LR cd - - - 2 2
LR nt 1 10 3 9 23
DD - - 1 - 1
NE - 1 - - 1
I - - - - -
TOTAL 6 30 14 22 72
21
EX-extinct; EW-extinct in the wild; Ex/E-extinct/endangered; CR-critically endangered ; EN-endangered;
VU-vulnerable; R-rare; LR-lower risk (nt-near threatened; cd-conservation dependent); DD-data deficient;
NE-not evaluated; I-indeterminate
22
For plants, the pre-1994 IUCN Red List Categories was used.
23
Ibid.
The Impact of Dams on Life in Rivers 28
12
Brazilian Tapir
24
Phot above: Giant Anteater
24
http://www.interlog.com/~insight/iwokrama/mammals/guides/ante0.html
12
http://vivabrazil.com/images/anta.jpg
The Impact of Dams on Life in Rivers 29
REFERENCES
Bernacsek, G.M. 1992. Research priorities in fisheries management as a tool for wetlands
conservation and rural development in Africa in Conservation and Development: The
Sustainable Use of Wetland Resources, IUCN, Switzerland, 131-144.
Gujja, Biksham and Perrin, Mireille. 1999. A Place for Dams in the 21st Century? WWF
International, Gland, Switzerland.
Hertlein, Luke M.A. 1999. Lake Winnipeg Regulation Churchill-Nelson River Diversion
Project and the Crees of Northern Manitoba, Canada. Prepared for the Forest Peoples
Programme and the World Commission on Dams. Consultative Meeting on Dams,
Indigenous Peoples and Ethnic Minorities, July 31 to August 1, 1999, Geneva.
Switzerland.
Legal Assistance Centre. 1998 and 1999. The Epupa Debate and Case study on the
proposed Epupa Hydropower Dam in Namibia. Documentation presented at the
Consultative Meeting on Dams, Indigenous Peoples and Ethnic Minorities, July 31 to
August 1, 1999, Geneva. Switzerland.
McCully, Patrick. 1996. Silenced Rivers. The Ecology and Politics of Large Dams. Zed
Books, London, UK.
Moore, Deborah. 1999. Speech given at the Seventh Conference of the Parties to the
Ramsar Convention on Wetlands of International Importance, Costa Rica., May 1999.
Ramsar, 1998. The Key Role of Wetlands in Addressing the Global Water Crisis. Paper
prepared by the Bureau of the Convention on Wetlands, International Conference on
Water & Sustainable Development, Paris, March 1998, 6 pages.
Reeves, Randall R. and Leatherwood, Stephen. 1994. Dams and River Dolphins: Can
They Co-exist? in Ambio, Vol. 23 No. 3, May 1994, Royal Swedish Academy of Sciences.
Smith, Brian D. et al. 1998. Profile: River Dolphins in Bangladesh: Conservation and the
Effects of Water Development in Environmental Management, Vol. 22, No. 3, Springer-
Verlag, New York, USA, pp. 323-335.
WEB sources
http://natsafaris.com/beco2.htm
http://www.southwest.com.au/~kirbyhs/pinkdolphins.html
http://www.irn.org/pubs/wp/dolphin.html
http://www.delm.tas.gov.au/esl/pedder.html
http://www.mlists.net/sindh-intl/mail/mail_kalabagh.htm
http://www.riogrande.com.br/turismo/riozinho_faunaflora.htm
http://www.ucm.es/info/zoo/Vertebrados/papers.htm#Papers on Sturgeon
The Impact of Dams on Life in Rivers 31