Regional Leadership Forum Advancing Sustainable Hydropower in Latin America and the Caribbean

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Organização Industrial e Engenharia
Water Storage for Sustainable Development
and Poverty Eradication
Francisco Luiz Sibut Gomide*
June, 2012
*Ph.D.(Colorado State University, 1975) Professor Titular (Universidade Federal do Paraná, 1986)

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TABLE OF CONTENTES
INTRODUCTION .............................................................................. 2
NATURAL LAKES AND MAN MADE RESERVOIRS .............................. 3
THE IRRATIONAL OPPOSITION ........................................................ 4
THE ESSENTIAL INFRASTRUCTURE .................................................. 5
THE WATER (AND HYDROPOWER) CONTINENT ............................... 6
THE STORAGE YIELD RELATIONSHIP ................................................ 7
CLOSURE ........................................................................................ 8
REFERENCES ................................................................................... 9
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INTRODUCTION
For thousands of years, dams and reservoirs have been important tools for the
administration of extreme hydrological events. Water related disasters such as floods and
droughts have been successfully mitigated by the intelligent use of the storage provided
by reservoirs.
Up to the last quarter of the 20th century, those responsible for the construction of dams
and creation of reservoirs – entrepreneurs, decision makers, engineers, investors –were
praised for the acknowledged benefits of their works: water supply, irrigated agriculture,
flood control, improved navigation and firm hydroelectric generation (then considered
clean and unequivocally renewable energy).
In the last thirty to forty years, on one (positive) side, a great consensus has been reached,
concerning the need for natural systems preservation and proper environmental
protection. However, on the other (negative) side, alarmist groups and organizations have
been exaggeratedly stating that infrastructure works, in general, and dams and reservoirs,
in particular, cause serious and intolerable environmental impacts.
Since the eighties, specific organizations have succeeded in coercing multilateral credit
institutions – such as the World Bank – to drastically reduce the technical and financial
support for the construction of hydroelectric plants, seriously jeopardizing their
commitment to poverty reduction.
One may even dare to state that this was the starting point of a process aiming at the
criminalization of reservoirs. According to some groups and organizations, hydroelectricity
would not be “clean” and could not be considered renewable, because of the reservoir. In
consequence, reservoirs also would not be acceptable for water supply, flood control,
irrigation etc.
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NATURAL LAKES AND MAN MADE RESERVOIRS
The volume of fresh surface water in the earth is only 0.0075% of the total global water
(Gleick, 1996): 104,620 km3, distributed in lakes (90,990 km3), swamps (11,510 km3) and
rivers (2,120 km3). According to the International Committee on Large Dams – ICOLD, the
total water storage in man-made reservoirs is around 6,620 km3 (White, 2010).
The services of ecological systems such as water regulation, water supply and disturbance
regulation (say, flood control), produced by natural capital stocks (lakes, swamps and
rivers), are duly appreciated (Costanza et al, 1997). The idea behind man-made reservoirs
is to offer these very same services, plus hydroelectric power, improved navigation and
expanded recreation opportunities.
Mother Nature decided (randomly, of course) that USA deserved some 19,000 km3 of fresh
water stored in natural lakes. That seems to be fine. But when the American human
ingenuity provides around 800 km3 (or maybe 1,000 km3) (NOOA, 2012) of additional
freshwater storage in man-made reservoirs, then, according to some organizations, an
ecologic mistake has been perpetrated. And because these extremist organizations believe
that all errors – even the imaginary ones – must be punished, they decided: “no more
dams”.
There are more than 75,000 dams in USA, with age over 50 years, on the average. Even so,
there is no evidence supporting the assertion that building them was a mistake. The
benefits of their reservoir operation largely offset eventual environmental impacts.
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THE IRRATIONAL OPPOSITION
The motivation for the irrational opposition to dams and reservoirs remains an unsolved
mystery. How can anyone justify the opposition to the service of water regulation? And
the opposition to the service of water supply? How can anyone waive the protection
provided by reservoirs in flood routing? How can anyone criticize man-made reservoirs
without regretting the existence of natural lakes? How can anyone favor the replacement
of renewable energy (such as hydroelectricity) by thermal electricity (from fossil fuel
combustion)? How can anyone pretend there are more risks in hydroelectric projects than
in thermonuclear electric plants?
Apparently, the opposition to dams and reservoirs is the consequence of two acts of
denial. The first one is to deny that, following the change in ecological balance caused by
man-made works, remedial measures are available to facilitate the adjustment of
biological species to a new, often better ecological environment. The other denial is the
refusal to acknowledge that in many cases, one must contemplate the relocation of
population installed in inappropriate places, from the standpoint of the highest public
interest. And that it can be done in such a way to improve the well-being of the relocated
populations in a wide variety of aspects.
Environmental protection is a moral obligation of mankind. This song is very good. But
not all singers are good. The irrational opposition to dams and reservoirs facilitates the
adoption of the environmental flag by insincere people, groups and organizations, to be
used as a mere public relations instrument.
To be rational, the debate would have to be conducted in the context of comparison of
alternatives and trade-off analyses. Particularly in Brazil, the mistaken application of the
principle of precaution has transformed most dam construction initiatives in time
consuming, long legal battles. In the meantime, the increasing demand for electricity has
been supplied by fossil fuel fired thermal plants, with more pernicious environmental
impact!
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THE ESSENTIAL INFRASTRUCTURE
Unfortunately, the mistaken opposition to dams and reservoirs was so efficient in forcing,
coercing and influencing people and organizations that aid agencies and other
multilateral institutions discreetly steered away from investments in infrastructure.
However, investment in infrastructure is indispensable for sustainable development and
poverty eradication. Sustainable development implies in the optimum conversion of the
resources of nature to benefit mankind, including the future generations. Poverty
eradication requires concrete actions such as infrastructure works to assure universal
access to water and electricity.
According to Yevjevich (1999), one may safely state that a civilization is as good as its
infrastructures. Rich countries are living off the convenient services provided by
infrastructure developed in the 20th century, which is aging. At the same time, pointing to
poor countries, this rich countries agenda advocates a path to development that no one
has taken before (Briscoe, 2011).
It looks like the story of the Directors of a club – the riches’ club – writing down rules for
the selection of new members, setting up conditions not fulfilled – today or ever – by the
existing members. Furthermore, rules such that, once fulfilled, would make it impossible to
become a member of this club!
The end result of the irrational opposition to dams, reservoirs and other infrastructure
works is that the 20th century was closed with 850 million people without adequate access
to water, 1.6 billion people without access to electricity and 2.9 billion people living on less
than 2 dollars a day.
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THE WATER (AND HYDROPOWER) CONTINENT
The globally averaged annual precipitation over land is less than 800 millimeters
(Shiklomanov and Sokolov, 1983). It does not change much from one continent to the
other (Europe, 790mm; Asia, 740 mm; Africa, 740 mm; North America, 756 mm; Australia
and Oceania, 791 mm). The exception is South America, where it is twice as large: 1600
mm. In Brazil, it is even larger: 1800 mm. In the Brazilian Amazon, annual rainfall is more
than 2200 mm. For the Amazon as a whole, rainfall is over 2400 mm, more than the triple
of those average 800 mm!
More than 25% of the total water flux in the planet occurs in South America: the mean
annual global run off is 47,000 km3 and the South America’s is 12,200 km3. The Brazilian
mean annual run off (5,667 km3) triples the American one (1,787 km3), and the countries
(Brazil and contiguous USA) are comparable in area. Furthermore, the three largest
concentrations of hydropower potential in the planet are in South America, two of them in
Brazil.
The Brazilian electricity sector is - and hopefully will continue to be – basically hydraulic.
Thanks to hydroelectricity the Brazilian energy mix is one of the cleanest and most carbon-
free in the world. Most of the Brazilian freshwater storage in man-made reservoirs (653
km3 out of 724 km3) has been provided by electricity generation companies.
Assuming that the total freshwater storage in American man-made reservoirs is 810 km3,
one may state that this is equivalent to 165 days of long term mean run off
[810/(1787/365)≈ 165]. Comparatively, the Brazilian total freshwater storage in man-
made reservoirs is small: 47 days [724/(5667/365)≈47]. Disregarding the electricity sector,
it would drop dramatically to less than 5 days [71/(5667/365)<5].
The reservoirs belonging to the Brazilian electricity sector have a total surface area of
37,000 km2. For comparison purposes, it may be mentioned that 90% of the 90,990 km 3 of
freshwater storage in natural lakes is concentrated in just eleven locations, with mean
surface area of 44,800 km2. Eight of these lakes are in the northern hemisphere; three are
in Africa and, of course, none in South America.
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THE STORAGE YIELD RELATIONSHIP
Estimators of long term storage requirements are proportional to the standard deviation
of the net inflows to reservoirs (Gomide, 1975). In the context of climatic changes, the
importance of reservoirs is increased: floods and droughts are expected to be more
frequent, and the progressive concentration of occurrences in the tails of the probability
distribution inflates the standard deviation of the net inflows, indicating the need for
larger reservoirs.
There is an optimal size for reservoirs: not too small, to be useful, and not too large, due to
the diminishing marginal returns. This is well illustrated by the so-called storage-yield
relationship (SYR), a well-known hydrologic tool. For any given combination of planning
horizon (in years) and risk to be assumed, this curve (SYR) furnishes the storage required
for each value of “firm” (or “guaranteed”, or “assured”, or “sustained”) yield of river
discharge.
Of course, no storage is needed to assure the minimum (for this specific risk and horizon)
discharge. The curve (SYR) is a monotonously increasing function. The maximum storage
corresponds to the maximum sustainable firm flow, which is the long term mean discharge
(LTMD). The inclination of the tangent to this curve (SYR) is equal to the duration of the
drought (“critical” period). To illustrate the diminishing marginal returns, it can be shown
that for a SYR applicable to typical Brazilian conditions, one can “firm” more than 85% of
the long term mean discharge, with less than 30% of the storage needed to “firm” 100% of
the LTMD (Gomide, 2012).
Not always the water intake location is adequate for the creation of a sizable reservoir.
The probabilistic design does not change as one moves upstream looking for more
adequate sites; but the maximum sustainable firm flow decreases, of course. The
comparative analysis of the duration curves (another well-known hydrologic tool) for both
river cross sections will define, together with the storage-yield-relationship, the limits and
details of the feasible decisions regarding firm flow.
When dealing with energy regulation rather than water regulation, the flexibility is
immense: the storage has not even to be upstream! Adequate designed transmission lines
will transport energy from one point (where it is available) to other (where it is needed).
Furthermore, as the system increases in size, adding new plants located in hydrologic
diverse regions, the standard deviation of the total inflow increases at a lower rate in
comparison with the mean. In other words, the coefficient of variation decreases, what
implies is higher storage efficiency (Gomide, 2012). The synergetic Brazilian electricity
sector has been, for decades, an interesting demonstration of this mathematical property
of the partial sums of random variables.
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CLOSURE
Infrastructure investment is central to the world’s objective of poverty eradication. There
can be no poverty reduction without access to water and electricity. Investments in
sustainable multi-purpose water storage must be encouraged. Reservoirs are not only
useful. They are indispensable. Reservoirs do change the ecological balance, initially.
However, the evidence of successful adaptation to the new – and often better –ecological
environment is overwhelming.
Each and every human intervention on Nature has environmental impact. Hydroelectricity
is favorably compared with most other generation alternatives. Accordingly, hydro-power
must be acknowledged as an unambiguously renewable source of energy.
Reservoirs take advantage of hydrologic diversity to bring in synergic gains to the
operation of complex hydroelectric systems. Reservoirs and other infrastructure works are
indispensable for water regulation (low flow augmentation), water supply, waste
treatment and disposal systems and flood control.
The concentration of reservoirs in the upper portion of the hydrographic basins, as a
consequence of the search for more adequate dam sites, is consistent with the
probabilistic design of the storage requirements and with the environmental protection of
the watersheds.
Sustainable development implies in the optimum conversion of the resources of nature to
benefit the today and future generations. There is no conflict between the fortunately
predominant advanced level of global environmental awareness and the timely
convenience of the effective development of the Brazilian extraordinary water resources.
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REFERENCES
Briscoe, J. “Making reform happen in Water Policy: Reflections from a 2011
practitioner”, OECD Global Forum on Environment: Making water
reform happen, OECD Conference Center, Paris, 25-26 October 2011
Costanza, R., d’Arge, R., de “The value of the world’s ecosystem services and natural capital” 1997
Groot, R., Farber, S., Nature, volume 387, pp 253-260, May 1997
Grasso, M., Hannon, B.,
Limburg, K., Naeem, S.,
O’Neill, R.V., Paruelo, J.,
Raskin, R.G., Sutton, P. e
van den Belt, M.
Gleick, P.H. “Water resources”, Encyclopedia of Climate and Weather, ed. by S. H. 1996
Schneider, vol. 2, pp 817-823, Oxford University Press, New York
Gomide, F.L.S. “Range and Deficit Analysis using Markov Chains”, Hydrology Papers, 1975
v 4, n 79, Colorado State University, Fort Collins
Gomide, F.L.S. “Sobre Reservatórios e Segurança Hídrica”, to appear 2012
NOAA National Oceanic and Atmospheric Administration 2012
http://www.nwrfc.noaa.gov/info/water_cycle/hydrology.cgi
Shiklomanov, I.A. e “Methodological basis of world water balance investigation and 1983
Sokolov, A.A. computation”, Proc. Hamburg Workshop, IAHS Publication n 148
White, W.R. “World Water: Resources, Usage and the Role of Man-Made 2010
Reservoirs”
Yevjevich, V. “Quo Vadis, America?”, Highland Ranch General Publishing 1999
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