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[INLINE] ICID Draft Position Paper on Dams
_________________________________________________________________
ICID Draft Position Paper on the role of dams for irrigation, drainage
and flood control for consideration of World Commission on Dams
(January,1999)
1. Dams and stakeholders
2 A backgrounder about dams
3 ICID's position
4 Remarks by AFEID
_________________________________________________________________
1. Dams and Stake Holders
------------------------------
1.1 Dams - large and small : Although dams have been built in the
world since times immemorial, large dam construction was earlier not
possible though needed, because of lack of adequate design knowledge,
the requisite mechanical equipment and materials and technology of
construction. It became possible only during the 20th century mainly
because advances made in Science and Technology, which enabled
mechanisation of construction processes and speedier construction on
one hand. On the other, vastly improved design procedures and new
construction materials enabled design of larger dams and their
components to take on much higher loads and stresses. Large dams as
distinct from smaller dams enabled larger storage of water at one
topographically suitable place, thus saving on multiplicity of effort
instead, to build several dams.
1.2 Main stakeholders: The large dams enabled harnessing of large
water resource potential, where and when available, to meet with needs
of fast growing societies round the world, like food, fodder, drinking
water, clothing fibres, sanitation, energy, industry and others. After
several decades of evolving dam construction activity, even today's
needs are far from satisfied in many developing and underdeveloped
countries. These people of the World comprising, the farmers who grow
food; the industries, the municipal institutions who use the water
stored behind the dams, besides the Governments who promote the water
resources development (WRD) are the major stakeholders in dams which
have been so far built. Besides, those thousands of dams which are yet
to be built, especially in the developing and the underdeveloped
world, without which the existence of their societies itself is at
stake are important stakeholders.
1.3 Affected people: Another important group of stake holders is of
people adversely affected due to dams. There is yet another group of
people namely conservationists who feel strongly that enough is not
being done by the society while building dams to conserve the
environment and ecology.
1.4 Dam builders and professionals: The planners and builders of dams,
users of water, supported by financiers, sociologists, economists,
politicians who promote dams form another group of stakeholders. There
are several associations of these stake- holders. Three majors of such
world bodies are:
International Commission on Large Dams (ICOLD) established in 1928.
International Commission on Irrigation and Drainage (ICID) established
in 1950.
International Hydropower Association (IHA) established in 1995.
There are some 10 similar Global Associations of professionals dealing
with one or the other facet of dams and have a stake in the matter.
Recently the World Commission on Dams (WCD) has been established.
1.5 ICID: Sustainable irrigated agriculture, requisite drainage of
irrigated land, and flood control and management - comprise the main
action thrusts of the ICID. All these are directed to ensure continued
food security through not only extension of irrigated areas but also
increase in productivity, and through it transformation of rural
development scene, throughout the world. A recent report by
International Water Management Institute (IWMI) indicates that in
spite of best irrigation efficiency, the world would be needing
extension of irrigated areas. To achieve these objectives, ICID acts
through its country membership, which at present includes 67 countries
as active members and another 20 countries, which are not so active.
Together they account for most of the irrigated area of the world
admeasuring about 17 % of the cropped area but which contributes about
40 % of the global food production. It has more than 25 work bodies
comprising international experts dealing with some of the issues
related to the role of dams for irrigation, drainage and flood
control. The themes covered by these bodies include Environmental
Impacts of Irrigation, Drainage and Flood Control Projects,
Socio-economic Impacts and Policy Issues, Research and Development,
Irrigation and Drainage Performance, Sustainable Use of Natural
Resources for Crop Production, etc.The ICID gathers experiences
through these work bodies world wide, draws lessons and builds them in
the strategy for future.
ICID aims to provide better management for the agricultural lands of
the world through the application of science and techniques of
irrigation, drainage and flood control measures. In pursuing its aims,
ICID embraces the sound principles of socio-economic values and
environmental management. The welfare of the people and preservation
of nature are at the heart of our concerns. Dams of all sizes small,
medium and large are an essential component of overall and integrated
water management systems. They divert water, they retain it over long
periods of time to use it rather than lose it, and they attenuate
peaks and valleys in seasonal flow rates. They regulate rivers to
mitigate floods, they provide for drainage relief, and they provide
for the timely and continuous supply of irrigation water needed to
meet the demands of crops and livestock. The survival of the human
race in the next millennium will be tied to the success in managing
fresh water worldwide. Existing and new dams will continue to play a
major role in the management system.
The International Executive Council (IEC) of ICID meets every year.
During the 49th meeting of IEC held at Bali (Indonesia) in July 1998,
it was decided to prepare an ICID position paper for consideration of
WCD. The present paper constitutes a preliminary response from ICID.
2. A backgrounder about dams
--------------------------------
2.1 Large dams: All dams store behind them flood-waters which
otherwise would run to sea without being put to use for humans, or
flora-fauna. ICOLD defines large dams as more than 15 m in height,
while including smaller dams up to 10 m height also, if they are
otherwise large in other respects. The classification is notional. But
because of possibility for deployment of sophisticated technology and
concentrated work, larger a dam, the cost per unit of water stored is
usually less.
2.2 Choice of size: The storage of water enables removal of mismatch
between variable availability and supply, but relatively more even
demand, round the year. For this purpose, many dams are designed to
carry over the storage to the next season also. The variability if not
taken care of by such storages, results in drought and or floods. All
dams large and small - mega to micro ameliorate such conditions and
serve similar purpose. All dams facilitate transport of water to
deficit areas by means of open canals, tunnels or closed pipelines. In
a river basin, a judicious combination of large and small dams is
required to store required water for facilitating withdrawal and use
with minimum transport distance to demand regions. The choice of large
or small dams and location for each of the dam depends on several
factors including technical feasibility, location of water deficit
regions that need to be serviced and alternatives available for the
purpose.
2.3 Storage and quantum for beneficial uses: All the water stored
behind dams is not withdrawn for use. A top depth varying from 1 to 2
meters depending on local climate, is lost to atmosphere due to
evaporation. At the bottom, some depth serves as a silt pocket for
accommodating sediment brought in by inflow. The remaining volume
minus the seepage from the bed of the reservoir and that across the
dam foundation and body, is available for transport and supply for
different beneficial uses. As the depth of storage lost due to
evaporation is same, the quantity is proportionately more when height
of dam is small as compared to a higher dam. Silt pocket size depends
upon the catchment area characteristics but similar to evaporation
losses, tends to be proportionately more in case of a smaller dam.
Storages provide insurance against uncertainty due to climatic
variability, can help reduce season's low flows in rivers and save
societies from economic upheavals due to flood and drought losses.
2.4 Disadvantages: Every dam causes submergence of land in the
upstream and displacement of resident persons and their property
generally, along-with submergence of plant life and disruption to
animal life. In downstream also, such effects are caused due to
ancillary facilities on a similar but on a much smaller scale. The
consequent social and economic loss is generally assessed and compared
with benefits due to the dam. The downstream uses are met with mostly
from flow by gravity or regulated releases into the river, whereas in
the upstream, lifting of water is involved.
2.5 Withdrawal for irrigation: A major portion of the waters stored
behind dams in the world is withdrawn for irrigation which mostly
comprises consumptive that is evapo-transpiration (ET) needs of
irrigated crops / plantations. A majority of the dams built in the
world are multipurpose in nature, but most of them cater to irrigation
needs. These dams were responsible for bringing under cropping,
additional areas and ushering the green revolution through high
yielding crops and application of fertilisers, a few decades ago,
imparting food security in the face of ever-growing population. Water
used in excess of ET needs, however appears in the system as surface
or ground water, albeit with degradation in quality mainly due to
fertilisers and pesticides, besides minerals drawn from soils. Such
waste has to be minimised to se riparians dependent on lean season
flow have to be provided with supplies from upstream withdrawals.
2.8 Standards: The various professional institutions / associations,
Governments and Academia have during the last century evolved criteria
and guidelines for all aspects of decision making for dams. The
present day standards are a result of continuous review and
upgradation, through experience and generated knowledge. The standards
help assess availability, variability, statistical dependability,
storage size, risk analysis about chances of hydrological failure,
multipurpose sharing of reservoir space, sharing of costs,
environmental check lists, monitoring of environmental effects,
mitigation packages and efficacy of development effort. These are
besides the many Science and Technology based safe procedures, methods
and design of structures and their components.
2.9 Decommissioning of dams: The dam builders have not conceived so
far, 'decommissioning of dams' as a necessary step. Dams are complex
and major structures involving large investments. Some dams can prove
less effective than most, but efforts have been made to minimise the
reasons and increase the effectiveness through modernisation and
rehabilitation of such dams. At some places a larger dam has been
built in the downstream of an existing dam incidentally submerging and
decommissioning it. When a reservoir gets silted up over a period of
time, the dam has been used to work as a diversion structure for
withdrawals from run of the river, perhaps for shorter period in a
year. As the older dam would have by then paid back the investor in
more than ample measure, it becomes cost effective not to decommission
it.
2.10 Sustainability of development due to dams: The subject has been
debated extensively over the last couple of decades. The dams have
solved several problems of the communities served and have provided
basis for economic development that has sustained itself. Employment
opportunities have been generated, incidence of poverty has been
reduced, rural population including nomads has been stabilised locally
and migration of rural unemployed population to urban centers has been
reversed. Food security to ever growing population, protection from
floods and droughts to chronically vulnerable areas and generation of
the cleanest form of energy, namely hydropower, are some other
benefits of water resources development. Many urban and industrial
centres have been provided with water supply for consumption and
transport of waste for treatment. Navigation, fishery, irrigated
forestry, recreation and leisure are some other obvious benefits. The
all round development due to dams is there for everybody to see.
Benefits, costs and risks undoubtedly increase with size of a dam.
Efforts are made by dam planners to maximise benefits, minimise costs
and build in defensive measures in dam components to take care of
risks by deploying appropriate technology and design features.
Incidents involving dam failures are decreasing from decade to decade
and the safety record is comparable to any other human endeavour. Dam
safety assurance has been incorporated during the last two decades in
dam engineering from concept to O&M stage and has shown positive
effects on performance of dams.
2.11 Equity for the project people: The adversely affected people due
to a dam comprise those who are displaced due to inundation in
reservoir or due to ancillary structures. Some people dependent on
those displaced are incidentally affected. Some farms develop
waterlogging due to canal waters and the concerned farmers are also
affected. These people have to be rehabilitated and resettled with due
compensation and recognition for their sacrifice. Such R&R effected in
their consultation and with their consent can also include partnership
and ownership in the facilities and provide them economic benefits
flowing from the water resources development. The canals run along a
contour and provide irrigation water by flow in command area. For
farmers who are on higher level than the canal, and similarly those on
the fringe of reservoirs, lift irrigation facilities are provided. The
equity in supplies can thus be provided at local and regional level by
applying some basic economic principles.
2.12 Summing up: While large quantities of fresh water are yet flowing
to seas through rivers, scarcity is engulfing many countries of the
world. Thousands of dams are to be built to store such water and make
it available, during the next century round the world, especially in
the non-industrialised countries of Asia, Africa, Latin America and
East Europe. The needs of growing populations, the pace of
urbanisation and industrialisation, and the urgent need to improve
standard and quality of life of poorer sections of their societies
calls for urgent steps to build these facilities. It will be an
enormous challenge to decision makers, developers and designers to
develop the economically required capacity in an environmentally sound
and sustainable way.
3. ICID's position
----------------------
3.1 Development effectiveness of dams
Large or small dams, if built without adequate preparatory work, can
fail to deliver expected results. Either or any dam could thus prove
less effective than planned. It is therefore necessary to select cited
cases of success or failure of both large and/or small dams. Lessons
are to be drawn from failures for rectification in future dams. The
owners of such dams have to be approached first, for their
assessments. If a new dam is identified, a bench-mark status if not
available at the time of construction, might have to be ascertained to
realistically assess its effectiveness.
3.2 Assessment of options and decision making framework
3.2.1 Sustainability: It has become the touch-stone for development
effort since Agenda 21 was adopted at Rio Conference in 1992. Although
its definition has had different connotations for various development
sectors, it means that fruits of development ought to be of sustained
nature to meet with needs of future generations also, and should not
be of transient nature to address only present day concerns. Recently,
the Global Water Partnership has come up with the following definition
of Integrated Water Resources Management, "a process which aims to
ensure the coordinated development and management of water, land and
related resources to maximise social and economic welfare without
compromising the sustainability of vital ecosystems". For instance, in
case of dams, the present decisions ought to result into outputs for a
long enough time. It is possible only through integration of
development and management of water resources (IWRDM) which is
enshrined in Agenda 21. While achieving it, quality and quantity i.e.
sustainability of natural resources themselves must not be affected.
Dams have a finite life like any other man-made structure. The right
combination of large and small dams in a river basin, which provides
such sustained fruition throughout the structures' life, has to be
ascertained by scientific case specific study. The IWRDM has to
address the needs of the ultimate stable size of global population,
expected to be attained, hopefully, say by the middle of the next
century. Such needs can be met with from basin-wise availability,
through the desired combination of dams to provide a model for
sustainable development. Within a basin itself, conflict of interests
often manifests due to perceived shortages, regarding size of dams.
Appropriate policy and guidelines are called for to resolve such
conflict
3.2.2 Integration of options: The alternative to such discrete
combination, as proposed by those who oppose large dams, is to go in
for minor dams and micro watershed development schemes only. The minor
dams have a definite role to play in a basin, along with major dams.
Micro watershed development basically is useful in rain-fed areas,
which cannot be served by canals starting from dams or by ground water
facilities. About half of the sown area in the world is likely to
remain dependent on rains. For such area, micro watershed development
usefully provides protection from variability in rainfall in a rainy
season. It ensures fair growth of one crop, by retaining soil moisture
over a longer period and increases yield. The dams and the micro
watershed development are thus not alternatives, but are complementary
to each other to increase food productivity of cropped land and to
ensure food security, for the ultimate size of population.
3.3 Issues related with planning, implementation, socio-economic
aspects
3.3.1 Decision support systems: Planning and implementation of
different facilities created for land and water development have
evolved over the last 100 years utilising advances made in Science and
Technology. For micro watershed development also, sufficiently
detailed criteria have been developed over the last two decades.
Spatial decision support systems have been developed to take into
account hydrologic, land use, bio-mass, energy and socio-economic
components for small watersheds. In view of low food productivity of
rain-fed areas around the world, several countries have taken up such
development.
3.3.2 Economic analysis: Socio-economic impacts of large dams and
alternative of micro watershed development have been studied
extensively. As mentioned earlier, larger a facility, the benefits,
costs, and risks are usually larger. But while planning a facility,
effort is made for maximising benefits and minimising costs and risks.
A view is taken, on the balance, of advantages to the community. The
benefit cost (BC) analysis has to include social benefits and costs
streams to expand it to Social Benefit Cost Analysis (SBCA). It is
difficult to accurately quantify secondary and incidental benefits and
costs. The SBCA essentially helps a planner to prioritise projects for
implementation. The BC ratio normally drops with the size of the
facility. Smaller the size, smaller is the gestation and construction
period, but the life span of the structure is also smaller, operation
and maintenance costs are higher, dependability is smaller and hence
the BC ratio drops.
3.3.3 Prioritisation: For many countries of the world, facilities
offered are required and still the level of water supply may remain
short of their ultimate requirements. In such cases, the BC analysis
does not help beyond prioritisation in face of resource crunch,
because even the most expensive facility may have to be put in place,
to meet with the needs of the society.
3.4 Environmental issues
---------------------------
3.4.1 Compensatory packages: Every human activity modifies the
environment. Some changes are for the good, some are not, but the
awareness in the society about size and scope of the adverse impacts
is playing an increasing role in decision making. Effort is made to
mitigate and compensate such effects, while increasing the positive
impacts so that sustainability of development is maintained and
natural resource base is not eroded. The challenge is to realise that
the positive effects on environment far outweigh negative effects.
Ameliorative measures have been evolved, over a period of time, by the
concerned professionals. ICOLD and ICID have prescribed detailed
listings, criteria and guidelines for study of environmental impacts
and their mitigation. Many countries have evolved appropriate packages
for compensating the negative impacts. These packages are being
refined further.
3.4.2 Adverse impacts with and without a dam: In the developing world,
canal and water development is required to take care of the population
pressures and the poverty level of societies. As development reduces
poverty level and improves, the standard of living mainly by providing
employment generation in itself has ameliorative effect on adverse
impacts. While adverse impacts of a dam can be taken care of, the
availability of freshwater on the other hand reduces environmental
degradation. The positive impacts on environment are manifold. In
absence of a dam or a water withdrawing facility, the environmental
degradation continues unabated especially in underdeveloped world
because of population pressures. Environmental impact studies
therefore have to be carried out for both, with and without dam
scenarios. The environmental cost of constructing a dam is normally
smaller than that in a situation without the dam if the continued
degradation in absence of a dam, due to poverty and population
pressures during the life of the dam, are considered. It is said that
the environmental cost of building and using a dam in a developing
country is normally smaller than that in not doing that dam project.
3.4.3 The check lists: The components of environmental impacts
normally considered are as follows: loss of land and biomass, forest
etc due to submergence; loss of land due to water-logging and
salinisation in irrigation command; deforestation in the command due
to bringing of new areas under cultivation; loss of passage for fish
and aquatic life; reduction of flow in the downstream river portion;
effect on flora and fauna in estuaries and mangroves regions. All
these effects can be ameliorated by means of adoption of appropriate
packages of remedies.
3.5 Development of internationally acceptable criteria and guidelines
The development of dams in the world has not taken place in a vacuum.
Large volume of documentation is available. The ICID, ICOLD and IHA
with the help of their participating nations around the world, for
instance, have developed a variety of standards and guidelines. They
have been adopted in international and professional fora and
fine-tuned especially during the last 50 years. Besides, most of the
nations have their own Standards Institutions, which develop such
codes which are statutory and hence adopted by dam professionals.
3.6 Institutional policy and financial arrangements for equitable
sharing of benefits, costs and risks
One principle that ought to be followed is that all those who are
benefited or who are adversely affected by dam projects are considered
and made shareholders of the project so that they get shares in the
benefit equitably. The standard of living and quality of life of those
adversely affected due to a dam, should be brought up to a level
higher than what it was prior to the dam project. The risks to the
society are generally limited to the downstream. Risks to the
structure due to deficiency in planning, implementation or natural
hazards have to be evaluated and integrated in the cost streams, by
adopting ample defensive measures. They have to be appropriately
worked out and provided in the overall planning of the area. Again in
this case, ICID believes that the risks to the downstream society due
to flood in absence of a dam are much higher, than the risks after
construction of a dam. An appropriate assessment of status of society
with and without dams has therefore to be made.
4. Remarks by AFEID
----------------------
The remarks of AFEID are based on the French experience on dams design
and management. 3 principles should prevail (this particularly
concerns section 3.6) which are applied for dams in France :
- the necessity of a sustainable management of the area downstream the
dam ;
- the necessity of a set of rules for socially acceptable water
sharing ;
- a conjunctive development and management of the whole river basin.
Concerning section 3.4 : The adverse impacts of irrigation on
environment can be reduced by a dam, which prevents the river being
dried up by the withdrawals for irrigation. Then it is necessary for
any dam to replace the usual supply policy by the management of the
water uses. Before the construction of any dam, the water management
of this new ressource shall be clearly decided :
- priority no. 1 Drinking water supply
- priority no. 2 Environment, with a minimum flow to be left in the
river (e.g. 10 % of the mean annual flow in France)
- priority no. 3 Irrigation and other economic usages, depending on
how water is valued
The french CACG (Compagnie d'aménagement des Coteaux de Gascogne) is a
good example of the environmental management of irrigation dams.
About life duration of dams (should be included in 2.9) : In most
cases, it depends on the silting up. No dam shall be built before the
control of the erosion in its catchment.
Last update : 07/05/99
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