Water Power and Dam Construction. Issue July 2010
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WWW.WATERPOWERMAGAZINE.COM JULY 2010 31
TUNNELLING
important in forming a reinforced rock ring to ensure the rock
masses support themselves, and thus prevent loosen zones
deteriorating further into rock masses.
For further information, please contact the authors via email:
Ziping.Huang@norconsult.com
Above: Figure 18 – Enhanced rock support in the downstream side roof,
springline and upper wall of the machine hall, photo by Ziping Huang
IWP& DC
References
Wu, S. and Huang, Z. 2008. Tunnel vision at Jinping. International Water Power &
Dam Construction. September 2008. Pp17-18.
CHIDI 05.2009, Stability analysis and rock support review report on the surrounding
rock masses of Jinping I hydropower project underground powerhouse caverns.
CHIDI 09.2003 Feasibility study of Jinping I hydropower project.
Left: Figure 11 – Layout of the monitoring cross sections, 1-1~9-9 in the powerhouse
complex, with the location of faults; Above: Figure 12 – Displacement distribution in
extensometers at Cross Section 4-4, in the machine hall and the transformer chamber;
Below: Figure 13 – Displacement distribution in extensometers at horizontal profile at
EL.1666, in the machine hall, transformer chamber and surge chambers; Left, below:
Figure 14 – Displacement curve with M6ZCF-Z3 at St.0+95.10 downstream wall of the
machine hall, in the vicinity of fault f14; Bottom, left: Figure 15 – Displacement curve
with M4ZCF3-5 at St.0+79.20 downstream wall of the machine hall at EL.1650, inte-
grated rock mass; Bottom, middle: Figure 16 – Displacement curve with M4PS2-8 at
St.0+126.8 downstream wall of the transformer chamber at EL.1668, integrated rock
mass in the vicinity of fault f18; Bottom, right: Figure 17 – Load vs. time of a cable
dynamometer at EL1661, downstream wall of the transformer chamber
32 JULY 2010 INTERNATIONAL WATER POWER & DAM CONSTRUCTION
NEW TECHNOLOGY
N
EW from Atlas Copco is the QAS 500 generating set which
offers dual frequency operation rated at 500kVA at 50Hz
(571kVA at 60Hz). It also has noise reduction and envi-
ronmental protection features for continuous on-site power
in industrial, public utilities and construction applications.
The QAS range, comprising a wide variety of models rated between
14–571kVA has been designed for fast, easy and safe transportation
and on-site handling on virtually any unprepared surface.
Housed in a noise attenuated enclosure made from zinc plated steel
and painted with powder coating paint, the QAS 500 meets a sound
power level (LWA) of 99 dB(A) at 50Hz; making it suitable for appli-
cations in noise sensitive areas. The enclosure also provides optimum
resistance against corrosion ensuring that it remains in good condi-
tion and retains an improved resale value, says the company.
An integrated lifting structure on the enclosure has been designed
to contribute to the total sturdiness of the set to ensure safe and ef-
cient handling. It is positioned in the centre point of gravity for cor-
rect balancing and is dimensioned to support at least four times the
maximum weight without breaking.
The integration of forklift slots also saves time and facilitates
safe and efcient handling and transportation. Well placed xation
points ensure safe transportation around the construction site, while
integrated bumpers protect the enclosure against mechanical impact
during transportation and handling.
The frame is also a 110% containment base for all the necessary
liquids such as oil, coolant and fuel.
EASE OF MAINTENANCE
Large access doors allow easy access to all service points and the gen-
erator components; developed to make any preventative maintenance
and repairs faster and easier.
External drain points are positioned to allow easy and efcient
draining of oil, coolant and fuel with minimised risk of environmental
spillage. Special drain points are also tted to allow the fuel tank to
be cleaned and water removed from the base frame; once again with
minimal environmental impact.
A 905 litre standard fuel tank, positioned in the centre of the base
frame ensures continuous operation at full load for a complete shift.
The new QAS 500 features a dedicated compartment for the electrical
cubicle making it safe to access even when ‘running.’ Isolating the electri-
cal components from the engine compartment provides reduced vibration
and temperature impact on the more sensitive electrical components.
An industrial type B-curve, four-pole main circuit breaker safeguards
the alternator against external short circuits by an instantaneous trip
three to ve times the nominal current. All main circuit breakers tted
in the QAS range are Omnipolar – an essential feature for compatibility
with the different congurations of customers’ applications.
FAIL SAFE PROTECTION
Critical engine parameters such as oil temperature, oil pressure and
coolant temperature are monitored by means of a failsafe system.
Should a sensor or transducer fail, the system automatically shuts
down to avoid any damage to the engine.
A dual stage fuel lter with integrated water separator and a heavy
duty dual stage air ltration system ensure longer service intervals
and increased engine life and up-time. An extra safety cartridge lter
element allows air lter replacement during operation.
Generator control, protection and monitoring are provided with a
local or remote start digital control module (Qc1002). Fitted as stand-
ard, the system is ideal for all automatic controlled applications. All
Qc controllers are equipped with external communication protocols
prepared to support the Cosmos option for satellite monitoring.
The Qc4002 controller is available as an option for multi start
paralleling operations. As a standard, this controller is equipped with
PMS (Power Management system), that enables the user to save fuel
and to extend the life time of the engine.
FULFILLING DEMANDS
To full the demand in the market for 800kVA, Atlas Copco has
upgraded its QAC 750 to the QAC 800.
The new QAC 800 delivers 800kVA of prime power at 50Hz to
meet increasing demands from generator users in the market. The QAC
series generators are built to withstand the most extreme temperatures,
and are designed to work in all weather conditions. A built-in engine
coolant heater ensures quick and easy start-up in cold conditions, while
a variable speed electric cooling fan allows continuous operation in
higher temperature environments, as in desert environments.
Designed with safety in mind, all QAC series generators have a
four-pole main motorised circuit breaker, providing overload and
short circuit protection, an emergency stop, automatic engine alarms
and shut-downs.
The double skinned and removable fuel tank with leakage sensors
and spillage free frame construction prevents accidental engine uids
or fuel spills, eliminating the risk of any ground pollution.
Easily handled by crane, lift or truck, the robust 20ft CSC ISO con-
tainer enclosure has lockable wide opening doors so that all compo-
nents are always within reach, ensuring that maintenance and service
is both easy and stress free, says the company.
The innovative dual compartment design – with the engine/alterna-
tor compartment separated from the cooler compartment – ensures
maximum efciency while operating in the most extreme conditions.
With the separated power cubicle, opposite to the control cubicle, a
safer operation is achieved.
The state-of-the-art Atlas Copco Qc 4002 control panel includes
features such as an LCD screen with numerous read-outs, warn-
ings and shutdowns – all displayed in various local languages.
Applications from ‘Island operation’ and ‘Automatic Mains Failure’
to the most complicated paralleling operations such as ‘Load shar-
ing,’ and ‘Base load’ operations, are done with this single, high-tech
generator controller.
This multi-purpose control system makes the QAC series genera-
tor an easy-to-operate machine, offering a single solution to varying
applications, says the company.
IWP& DC
IWP&DC looks at
Atlas Copco’s latest
developments in
generation technology
The generation game
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34 JULY 2010 INTERNATIONAL WATER POWER & DAM CONSTRUCTION
GENERATORS
T
HE energy and micro-generator manager (EMMA) is a
device that is installed alongside a micro-generator for
hydro, PV or wind. It monitors in real-time what your
micro-generator is producing and what energy you are
using in small commercial buildings or households. If it detects
there is surplus electricity available it then diverts this to an immer-
sion heater for the production of hot water or similar resistive load
device. This energy can then be stored and used when required.
The EMMA is benecial as between 45%, and in some cases 80%,
of what you generate is exported to the grid because of the miss-
match between the electricity generation and the demand proles.
EMMA matches these two curves. Up to 40% of household energy
requirements are for hot water and so the excess electricity is usually
put to good use satisfying this requirement. Over 60 devices have
been installed across Ireland and the UK.
THE YOUNG EMMA
EMMA was developed over two and a half years ago in Ireland where
there was no export tariff for any electricity put into the grid from a
micro-generator. Prior to development we had searched worldwide to
try and nd a similar technology, but as none was found we decided
to develop it ourselves.
The unique technical feature of the EMMA is that it seamlessly
ramps the electricity up and down to the immersion heater (or similar
resistive load device) using patented control technology. This may
seem a simple solution but it has taken many thousands of hours
of development time. In some countries the technology is nancially
very attractive. For example, in the UK you only get 3 pence per kWh
exported and so it makes sense to use the electricity in the house
rather than re-import it later. You receive the feed-in tariff based on
what you generate, not what you export. This is not impacted by
installing EMMA.
There are a variety of uses for EMMA, which include:
rIn any country where the export tariff for electricity is low or zero.
rAny house/small commercial/school with more than 1kW micro-
generator with immersion/ hot water tank.
rInstall with micro hydro, PV or micro wind.
rWhere client wants a micro-generator and a thermal solar system.
Put EMMA instead of thermal solar at 30% of the costs.
rWhere hot water is produced from electricity/gas/oil central heating
and uses a hot water cylinder.
rUp to 30kW (larger units are bespoke).
rGrid connected - three phase or single phase.
The main benets of using EMMA technology are that you can sig-
nicantly increase the rate of return on investment in your micro-
generator; help stabilise the distribution network; and further reduce
reliance on fossil fuels.
Figure 1 shows actual data from a site where an EMMA is installed.
There is a signicant miss-match between the demand and generator
output proles. This is typical of most sites where we have installed
EMMA and have been able to monitor this data.
Figure 2 shows the same site with the EMMA switched on. Here
the proles are matched perfectly within the operating constraints
of the generator. There are some times where the overall demand is
higher than the output from the generator. In this case the EMMA
ramps the immersion to zero and some electricity will be imported
to the household.
Generating interest in EMMA
Richard Linger from CoolPower Products in
Ireland introduces IWP&DC to EMMA: an
energy and micro generator manager which
is being used to optimise the performance of
a 90-year-old water turbine in the UK
Restored controls at a micro hydro site in Andover Drive mechanism at the Andover hydro site
WWW.WATERPOWERMAGAZINE.COM JULY 2010 35
GENERATORS
Effectively the energy produced from the micro-generator is priori-
tised. First use is always allocated to the household. Secondly to the
hot water production, if required, and thirdly to export to the grid.
This ensures the most effective payback for the user.
The EMMA can be used with other technologies and has been
connected to storage heaters and electric underoor heating systems.
It comes in a standard range of sizes from 4kW single phase up to
30kW three-phase phase systems. We can do larger devices but these
would be bespoke designs.
MICRO HYDRO INSTALLATION
We recently installed an EMMA with a 3.7kW micro-hydro genera-
tor in Andover, Hampshire, UK. This project has been a great success.
The client restored a 90-year-old turbine which had remained idle for
many years. On this site the client installed two heat storage systems,
one for his domestic hot water and the second for the central heating.
When there is excess electricity available it is put into the domestic
hot water cylinder rst, when this is full it then starts to heat the cen-
tral heating cylinder. The EMMA paid for itself in a matter of months
as the client was no longer using his large oil-red boiler to heat his
domestic hot water.
We are planning to install EMMA in a number of other micro-
hydro projects in the UK over the next 12 months. Most of these are
in remote areas where the EMMA can help further displace fossil
fuels and increase the rate of return on the micro hydro investment.
A recent development of the product is the grid voltage stabilisation
version (GVS) which we are trialling with UK network operators. The
EMMA GVS allows you to connect larger micro-generators to the
grid in areas where the network operator is imposing limits.
The EMMA GVS monitors the network voltage and the export
capacity. It can react by limiting export levels when the voltage is
higher than a specied point or simply limit the export capacity. The
benets are that you do not have to pay for a costly network upgrade
and can install a larger micro-generator to match your requirements.
You also get all the benets of the EMMA in terms of usage of energy
on-site, and reduced imports/costs.
The EMMA GVS can also be used where you have a high concen-
tration of micro-generators in an area. Here the benets are a stable
network and optimised use of the electricity being generated. There
are projects underway in the US trying to determine a solution for this
type of problem. EMMA GVS offers a solution.
The future offers exciting opportunities for EMMA technology. For
example, we are scoping an opportunity to pilot the use of EMMA
in demand side management/smart grids. As you are able to control
devices in response to signals sent to the EMMA, or in response to
voltage peaks or troughs, it can therefore be used to reduce the cost of
electricity supply or stabilise grid networks.
Richard Linger, Director Coolpower Products Ltd,
89 Booterstown Ave, Blackrock, Co. Dublin. Ireland
Email: Richardlinger@coolpower.ie
www.Coolpowerproducts.com
4000
3500
3000
2500
2000
1500
1000
500
0
17:45:00
19:00:00
20:15:00
21:30:00
22:45:00
00:00:00
01:15:00
02:30:00
03:45:00
05:00:00
06:15:00
07:30:00
08:45:00
10:05:00
0
0
0
0
0
0
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0
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Output
Demand
8000
7000
6000
5000
4000
3000
2000
1000
0
19:00:00
01:05:00
07:10:00
13:15:00
19:20:00
01:25:00
07:30:00
13:35:00
19:40:00
01:45:00
07:50:00
13:55:00
20:00:00
02:05:00
08:10:00
Demand
Output
IWP& DC
Top left: Figure 1 – Site where an EMMA is installed; Top right: Figure 2 – the
same site with EMMA switched on; Left: EMMA in stainless steel housing;
Right: Mill race and sluice gate at a micro hydro site in Andover, Hampshire, UK
36 JULY 2010 INTERNATIONAL WATER POWER & DAM CONSTRUCTION
MODELLING
I
N March 2009 Dave Holt, hydro project leader of the Goring
& Streatley Sustainability Group (GSSG) wrote the article
‘Power to the people’ for IWP&DC. This gave readers an
insight into the innovative hydro scheme that is planned for
the River Thames at Goring and Streatley in the UK.
The scheme comprises of three Archimedes screws driven by the
head difference of the Goring weir complex resulting in an estimat-
ed 246KW peak output. This renewable energy will be sold to the
National Grid to generate an income that will fund other local sus-
tainable projects in the area.
Since March 2009 Dave Holt and the GSSG have progressed with
the project and commissioned Peter Brett Associates (PBA) to assess
the ood risk associated with the scheme. Flood risk is an inherent
issue with such an installation and needs to be evaluated and miti-
gated against accordingly. The evaluation of the ood risk therefore
lends itself to a comparative exercise comparing the current or base
line ood risk against the ood risk with the proposed design in place.
This is best evaluated by quantifying ood levels for both scenarios
with a solution showing no difference between the two.
Through close liaison with the Environment Agency, PBA agreed a
methodology to assess the scheme using the powerful tool of hydrau-
lic river modelling.
GORING AND STREATLEY WEIR
Historically, water levels within the non-tidal section of the River
Thames have been heavily modied and managed through the con-
struction of weirs and locks for navigation and for powering numer-
ous mills for industry.
These weir complexes are still used today for managing water levels
for navigation and also for managing the ood risk to the towns and
villages that have expanded into the Thames oodplain.
Typically a weir complex consists of xed crest weirs with addi-
tional sluice or radial gates to manage water levels during times of
James Heptonstall from Peter Brett Associates provides an insight into the methodology
used for ood risk modelling on the River Thames in the UK
Assessing flood risks for Goring
and Streatley hydro
View west towards Goring and Streatley Weir
WWW.WATERPOWERMAGAZINE.COM JULY 2010 37
MODELLING
high or low ows.
The Goring and Streatley weir complex consists of two separate
areas divided by Withy Eyot. On the western (Streatley) side, the weir
complex incorporates a mill channel, two gated weirs, a Paddle and
Rymer weir, and a series of overow weirs. On the eastern (Goring)
side, the weir complex consists of three gated weirs, a series of over-
ow weirs, a lock island, a lock and a mill channel.
The proposed hydro power scheme is to be situated on the 16m
long overow weir adjacent to the lock keeper’s house on the Goring
side of the Thames. The screws would effectively obstruct 13m of
weir from the Goring and Streatley weir complex.
FLOOD RISK ASSESSMENT
English government Planning Policy Statement 25 (PPS25) requires
that new development does not create an increase in ood risk to
third parties.
The complexity of the Goring and Streatley weir complex and
ood hydraulics of the Thames along this reach required a hydraulic
modelling approach to satisfy the requirements of PPS25.
The Environment Agency, as regulators, worked closely with the
GSSG to produce a modelling specication that utilised their existing
strategic ood risk mapping ISIS (1 Dimensional) hydraulic model.
Using this model, PBA were commissioned by the GSSG to rst
provide a review of the existing hydrology and hydraulics of this
‘baseline’ model to assess the suitability of the model for assessing
ood risk at Goring.
Secondly PBA were requested to produce a design model that
included the three Archimedes screws, associated housing and con-
trol building. Each model would be run for three increasingly greater
magnitude ood events (1:5 year (222m
3
/sec), 1:20 year (284m
3
/sec)
and 1:100 year (355m
3
/sec). The predicted increase in ows over the
lifetime of the development from climate change was also accounted
for by increasing the 1:100 year ow by 20%.
A comparative exercise would be then carried out to assess how the
hydro power scheme impacted on ows across the weir system and
how this might impact on ood risk to third parties.
STAGE 1: MODEL REVIEW
The Environment Agency Strategic ISIS hydraulic model covers the
area between Sandford on Thames, 32km upstream of Goring, and
Whitchurch on Thames, 8km downstream of Goring.
The model represents the channel and floodplain using either
extended cross-sections or via a quasi two-dimensional approach
using lateral spills into reservoir units that represents large ood stor-
age areas within the Thames oodplain.
The strategic nature of the model meant that in rural areas,
where the channel and oodplain are uniform, model detail was
low with cross-sections spaced anywhere up to 700m apart.
However around the weir complexes such as at Goring and
Streatley, the model schematisation was found to be detailed and
provided a good representation of the weir hydraulics and there-
fore was suitable for the ood study.
The hydrology for the model was originally based on the
Dunsmore technique that estimates design ows from a ow-catch-
ment area relationship that can be derived from the long gauging
records on the Thames. The method was originally derived in 1991.
For this project PBA reviewed the results from the method using
the additional 17 years of extra ow gaugings made available by
the Environment Agency, which had been recorded on the Thames
gauge network since the method was derived. The method was
found to still provide a reliable estimate of design ows and so the
hydrology was left unchanged.
STAGE 2: HYDRO POWER MODELLING
The main components of the scheme include three, 3.6m diameter
Archimedes screw turbines, a control building and an additional
gated weir for mitigation.
The control building is to be designed to ood with any sensitive
plant set above the 1:100 year ood level including an allowance
for climate change and freeboard. The building itself will be small
enough not to impact on ood ows.
The three turbines are expected to occupy a 13m section of the
16m wide xed crest weir adjacent to the lock house. The additional
gated weir is then proposed to occupy the remaining 3m of the xed
crest weir.
A conservative assumption was made that the three turbines
would create a complete blockage over 13m of the existing xed
crest weir. This section of the weir was therefore removed from
the model.
Initial analysis of the model showed that the turbines had greatest
impact at low return period ood events, redistributing ow across
the other structures. The results also showed that the weir rapidly
became drowned out with increasing ows, caused by backing up
from a downstream railway embankment and bridge. As the weir
became drowned out, the impact from the turbines reduced to dis-
placing less than 4% of the total ow in the river, causing no change
in ood level.
Due to the sensitivity of some property in Goring and Streatley
to relatively frequent ood events, it was important that mitigation
was provided at the low return period events (1:5yr to 1:20yr design
events) to ensure no increase in ood risk to these receptors.
A gated weir was therefore proposed and modelled with a lower
xed crest than the existing weir. This effectively allowed an increase
in ow across the structure at the lower return period ood events,
fully mitigating for the hydropower scheme.
STAGE 3: APPROVAL
A ood risk assessment has been written based on the modelling
results and submitted to the Environment Agency, alongside the
hydraulic model for approval. The project has been run in close liai-
son between the Environment Agency, GSSG and PBA which has
thus far proved effective in moving the project forward in a consistent
direction. It is expected that this will continue with planning permis-
sion being sought later this year.
James Heptonstall, Assistant Hydrologist, Peter Brett
Associates, Caverhsham Bridge House, Waterman Place,
reading, Berkshire RG1 8DN, UK.
Email: jheptonstall@peterbrett.com
www.peterbrett.com
IWP& DC
Schematic of an Archimedes screws (Ritz-Atro)
38 JULY 2010 INTERNATIONAL WATER POWER & DAM CONSTRUCTION
SEDIMENTATION
L
ARGE dams have been constructed worldwide at a rate of
1.2 dams/day since 1930, based on the dams registered on
the ICOLD World Register of Dams. Many of these struc-
tures will continue to ll up with sediment as they age.
High rates of sedimentation in many reservoirs and better care of
long term sustainability have emphasised the importance of reser-
voir sedimentation. The main problems which can be encountered
include: loss of storage; damages to turbines and loss of hydropower
production; and downstream impacts.
The total world reservoirs storage is about 7000km
3
(6100km
3
based on the ICOLD Register of Dams, but if smaller <15m dams
are included, 7000km
3
could be the current total storage). About
3000km
3
of this is dead storage for hydropower. Of 4000km
3
of live
storage, most of this is devoted to hydropower and about 1000km
3
to irrigation dams, potable or industrial water storage; part of which
is in multipurpose dams.
The annual sediment load of the world’s rivers together is estimated
to be between 24-30B tons for a water inow of 40,000km
3
, ie an
average sediment content of 0.6-0.75T/1000m
3
of water but it varies
enormously according to the river and to the discharge. All rivers
are not dammed and all sediments are not trapped in reservoirs: the
accumulated sediment storage in world reservoirs has been evaluated
as 1400Mm
3
for 30 to 40-year-old dams on average, ie in the range
of 40Bm
3
per year, ie 0.6 % of the total storage per year.
The historical growth in storage capacity up to 2010 based on
the ICOLD World Register on Dams, and historical and predicted
reservoir sedimentation is shown in Figure 1.
Most sedimentation is at hydropower dams, partly in dead stor-
age but the loss of power supply is however not proportional to
the loss of live storage. The annual loss of power supply appears
in the range of 0.5% of a total investment of about US$1000B
for live storage, ie US$5B per year. As hydropower reservoirs silt
up however, they have to be replaced by new dams eventually at
a cost of the total storage capacity (dead and live) and at a total
investment of US$1700B, the annual cost of replacement is 0.6%
x 1700 = US$10B/year.
The annual loss of storage of irrigation reservoirs, possibly 7Bm
3
,
impacts directly on the irrigation capacity; for an investment of
Worldwide experts will convene in South Africa in September 2010. At the top of their
agenda is the growing problem of river sedimentation. Professor Gerrit Basson explains
why tackling this issue is of great importance to the dams industry
Tackling a
growing problem
US$0.2-0.5/m
3
for reservoirs in excess of 10Mm
3
, or up to US$1/
m
3
for dams smaller than 50000m
3
(often found in the Indian sub
continent and in Africa), with say a global investment cost of US$0.5/
m
3
the annual loss may be in the range of US$3.5B. There is also the
cost of downstream damages and, for possibly 5 or 10% of hydro-
power plants, losses of power supply and cost of maintenance for
turbine wear.
The total yearly loss linked with sedimentation problems is thus
about US$15B (excluding downstream impacts) and with downstream
impacts considered the annual cost is about US$17B. This should how-
ever be compared with the annual overall costs and benets of dams:
r Some US$40B of investments and US$17B for operation, main-
tenance and upgrading (0.7% x US$2400B; rate usually 0.3 to
0.7%), ie a total cost in the range of US$57B.
r Some US$125B of electric power supply (2500 TWH x US$0.05)
and other benets (especially food by irrigation for over 500 mil-
lion people).
The total yearly impact of siltation of US$17B should thus be com-
pared with the overall yearly costs (US$57B) and overall yearly benets
(US$175-225B) of world dams. The annual cost of reservoir sedimen-
tation (in terms of replacement cost) is about 30% of the overall costs
which is not insignicant. However, much less than 30% is currently
spent on sedimentation mitigation measures and the problems are
therefore postponed to future generations in many countries.
POTENTIAL IMPACTS OF STORAGE CAPACITY
Based on the ICOLD World Register on Dams, hydropower dams
make up 81.5% of the world’s total current storage capacity. In
2006, 35% of the total storage capacity for hydropower had been
lled with sediment. By 2050 this predicted proportion of current
total capacity that would be lled with sediment has risen to 70%.
For dams for any other purpose (non-hydro), in 2006, 33% of the
available capacity was lled with sediment, rising to a predicted value
of 62% by 2050.
It is expected that non-hydro dams will be severely impacted on
when they reach a 70% sedimentation level. At this sedimentation
level there will be about a 40-50% water yield reduction, and there
could be problems at the intakes. Based on the global data this will
occur by the year 2065, and will occur per region as indicated in the
table (p40).
Hydropower dams can generally be lled with sediment to a higher
level than non-hydropower dams, as it is mainly necessary to main-
tain the head for the power generation, and a storage capacity suf-
cient to meet all expected demands for power. It is expected that
hydropower dams will be severely impacted when they reach a level
of sedimentation of 80%. Based on the global data this will occur by
the year 2070, and per region as indicated in the table.
Countries that are anticipated to have critical sedimentation volumes
by year 2050 are: Afghanistan, Albania, Algeria, Bolivia, Botswana,
China, Columbia, Ecuador, France, Fiji, Iran, Iraq, Jamaica, Kenya,
Libya, Malaysia, F.Y.R.O. Macedonia, Morocco, Mexico, Namibia,
WWW.WATERPOWERMAGAZINE.COM JULY 2010 39
SEDIMENTATION
Time (years)
1980 1990 2000 2010
1940 1950 1960 1970
South America
North America
Middle East
Europe
Central America
Australasia
Asia
Africa
7000000
6000000
5000000
4000000
3000000
2000000
1000000
0
Gross storage capacity (million m
3
)
Opposite page: Sedimentation at a dam in Algeria
Left: Abstraction works to limit sediment in the Berg River
Above: Figure 1a: Historical growth in global storage capacity; Figure 1b:
Historical growth in global reservoir sedimentation (Basson, 2010)
South America loss
North America loss
Middle East loss
Europe loss
Central America loss
Australasia loss
Asia loss
Africa loss
4500000
4000000
3500000
3000000
2500000
2000000
1500000
1000000
500000
0
Sediment volume (million m
3
)
Time (years)
1980 1990 2000 2010 2020 2030 2040 20501940 1950 1960 1970
40 JULY 2010 INTERNATIONAL WATER POWER & DAM CONSTRUCTION
SEDIMENTATION
New Zealand, Oman, Pakistan, Puerto Rico, Saudi Arabia, Singapore,
Sri Lanka, Sudan, Tanzania, Tunisia and Uzbekistan.
SYMPOSIUM ON SEDIMENTATION
In order to help countries tackle the problems associated with sedi-
mentation, the 11th International Symposium on River Sedimentation
(ISRS) will be held in South Africa from 6-9 September 2010. The
ISRS is held to bring together scientists and engineers working in
the elds of river, lake and reservoir sedimentation, and covers theo-
retical and practical aspects related to sediment transport processes,
including environmental aspects. The impacts of hydraulic structures
on uvial morphology as well as measures to limit the impacts for
sustainable development of water resources are also key elements.
Other noteworthy areas include a focus on catchment soil erosion
programmes, sediment monitoring techniques, reservoir ushing
and other techniques to limit sedimentation, environmental aspects
including water reserve determination for river ecology.
Keynote presentation topics include:
r Mega deltas and the climate change challenges by Dr Kim Wium
Olesen, Head of Water Resources Department, DHI.
r Sediment Data Collection in Rivers, Reservoirs and Lakes by Prof.
Dr. Manfred Spreaco, University of Berne, Switzerland.
r Erosion and Sedimentation Research Emphasis in the USA by Dr.
Matt Römkens, United States Department of Agriculture (USDA)
Agricultural Research Service (ARS).
r An introduction to latest developments in soil erosion and sedi-
ment transport modelling by Dr. Weiming Wu, National Center
for Computational Hydroscience and Engineering (NCCHE), The
University of Mississippi, USA.
r New challenges in sedimentation and erosion research by Professor
Zhao-Yin Wang, Tsinghua University, China.
The four-day symposium also includes a technical visit to the recently
completed Berg River dam, the rst in South Africa where environ-
mental oods are released for ecology, in addition to erosion protec-
tion works at Cape Town.
Professor Gerrit Basson, Director of the Institute for
Water and Environmental Engineering; Department
of Civil Engineering; University of Stellenbosch, South
Africa. He is Chairman of the ICOLD Sedimentation
Committee (2004 to 2010). He can be contacted directly
about the conference at grbasson@sun.ac.za
IWP& DC
Growth hydro
Loss hydro
Growth other
Loss other
6000000
5000000
4000000
3000000
2000000
1000000
0
Storage capacity (mcm)
1900 1920 1940 1960 1980 2000 2020 2040
Year
References
Basson (2010). ICOLD Bulletin: Sedimentation and Sustainable use of
reservoirs and river systems. ICOLD Sedimentation Committee. Editor.
Year that current storage will
reach critical sedimentation
levels
Region Hydropower dams:
Date 80% filled with
sediment
Non-hydropower dams:
Date 70% filled with
sediment
Africa 2100 2090
Asia 2035 2025
Australasia 2070 2080
Central America 2060 2040
Europe and Russia 2080 2060
Middle East 2060 2030
North America 2060 2070
South America 2080 2060
Above: Testing of environmental flood releases at Berg River Dam
Right: Figure 2 – Global comparison of growth of dams by purpose
Symposium
The 11th International Symposium on River Sedimentation (SRS) is
organised by the University of Stellenbosch, near Cape Town. The ISRS
is held every three years with the World Association on Sedimentation
and Erosion Research (WASER) as the main sponsor. Others include: the
International Research and Training Centre on Erosion and Sedimentation
(IRTCES), UNESCO, ICOLD and the South African Water Research
Commission (WRC).
The main theme is sedimentation and the sustainable use of river systems.
Papers were also invited under the following themes:
r Reservoir/lake sedimentation modelling and management.
rSediment data collection in rivers, reservoirs and lakes.
rDam break analysis and sediment transport.
rReservoir sedimentation and management, such as ushing or dredging.
rSustainable tailings dams.
rUnlined dam spillway scour.
rHydraulics and environmental aspects of river sediment transport
processes (fundamental and modelling).
rFluvial morphological and environmental impacts of hydraulic structures on
the downstream river and possible mitigation measures.
rImpacts of river sedimentation on hydraulic structures (diversion,
abstraction works, bridges, etc.).
rSediment yield, soil erosion determination, modelling and management.
rClimate change impacts on sediment yields, river and estuary morphology
More than 250 delegates are expected to attend the symposium in
September. Note that the deadline for registration is 31 July 2010. Full
details can be found at: www.civeng.sun.ac.za/isrs