Transcript Case Study B Theme 1 Maldives on Desalination

Introduction
 1190 islands
 200 inhabited islands
 Population - 270,000
 Capital, Male’ – 74,000
 Annual rainfall – 1980 mm
 Elevation – Less than 2m
above sea level
Water Resources
Groundwater – private individual wells
public mosque wells
Rainwater – private rainwater tanks
public rainwater tanks
Traditionally the population
of Maldives has been
dependent on shallow wells
for its drinking water
l
Desalinated Water: Available in all tourist
resorts, the capital Male’ and
Kandholhudhoo island
Bottled Water :Imported from different
countries as well as produced in Maldives
History of water supply and
sanitation in Male’
1906 – Groundwater problems identified and
construction of public rainwater tanks began
1970’s - Frequent outbreaks of waterborne diseases due
to groundwater contamination
1980’s - Community and household rainwater tanks
and comprehensive sewerage system built
1990’s - Desalination found to be necessary and
expanded steadily to meet increasing demand
Occurrence of
groundwater resources
Groundwater found at shallow depths
Usually less than 2m below ground
Lens usually very thin
Less than 12m in most islands
Less then 2m in many
Vulnerability of
groundwater resources
Because they are shallow, groundwater
resources are prone to pollution from above
Because lenses are thin, they are prone to
increased salinity as a result of over
extraction
Sea level rises have also increased the threat
to Maldives’ groundwater
Groundwater pollution from
poor household sanitation
Relatively few heavy industries
Intensive agriculture on only a few islands
Major source of groundwater pollution is
poor household sanitation
Septic tanks and soakaways are often
corroded, poorly built or not maintained
Highly permeable soils
encourage pollutant transport
Inhabited areas have usually been cleared of
vegetation
Soils are highly permeable sand
Groundwater movement can be quite rapid
Pollutants can be transported over long
distances
Households depend
on their wells
Each household has its own well
Well water generally used for bathing only
During dry season, because rainwater
storage is insufficient, well water sometimes
used for cooking and drinking
Has a significant impact on health
High demand for groundwater
leads to increased salinity
Use of electric pumps has increased, but
over extraction can even occur where
simple dhanis are being used
Despite relatively low consumption on the
rural islands (80 – 110 L/p/d) population
densities are sometimes very high
Increased salinity can result
Problems exacerbated by high
population densities
Problems of pollution and over-extraction worsen
where population densities are high
Island
Area
(hectares)
Population
(2000 census)
Population density
(persons/hectare)
R. Kadholhudhoo
4.40
2650
602
Lh. Hinnavaru
7.24
3156
436
187.00
70278
376
B. Thulhaadhoo
4.97
1822
367
Sh. Komandoo
5.96
1526
256
Lh. Naifaru
14.27
3570
250
M. Dhiggaru
4.61
872
189
M. Maduvvari
3.10
455
147
K. Gulhi
5.50
613
111
B. Eydhafushi
22.20
2379
107
K. Male’
Factors other than population
density influence vulnerability
Geographical factors
High water tables
Narrow island width
Economic factors
Limit ability of communities to build good
sanitation facilities
Solid waste difficult to dispose of
Infrastructure provided to
address these problems
Sewerage systems built to protect groundwater
from pollution
Rainwater storage tanks provided
Free for community use
Cost recovery basis to households
On Kadholhudhoo and Male’, desalination has
become necessary
Plans to provide desalinated water for other
severely affected islands
Desalination in Maldives
In some islands the only means of providing a safe water
supply is by desalination
Desalination capacity in Male’ has been increased from
200m3/d in 1988 to 5800m3/d today
Desalinated water is provided through a pipe network and
is used for all purposes except toilet flushing
Those who cannot afford to have house connections are
provided with water from tap bays
Water Tariffs and Charges in Male’
Consumer Group
Rate of subsidy/Tax
Price to consumer, per m3
Domestic household
Up to 90L/day
MRf 25.32 (band A) (US$1.99)
“
90 – 270L
MRf 75.95 (band B) (US$5.96)
“
270L and above
MRf 101.26 (band C) (US$7.94)
Institutions
Metered flat rate
MRf 75.95 (US$5.96)
Commercial
Metered flat rate
MRf 101.26 (US$7.94)
•Note: Fixed Line charge MRf 30 per month (US$2.35)
•The tariff covers water and sewerage
•Average price for domestic customers is MRF 71.36(US$5.60)
Development of desalination capacity in Male’ (m3/d)
Desalination capacity has increased steadily since 1988
Plants donated by various countries have been
complimented by plants installed by MWSC
Improved energy efficiency
Since installation of desalination plants by MWSC
in 1995 energy consumption for water production
has fallen from 10 kW/m3 to 3 kW/m3 in 2002
Due to these advances in energy recovery the cost
of production has decreased
Costs are US $3.65 per m3 which includes
production, operation, maintenance and
administrative costs
Desalinated water is expensive in Male’
Average household spends between US $ 40 –60
per month on water ( 6 – 9% of their income) if they
use this for their basic needs
Advantage of the present arrangement is public
have the choice to use groundwater, rainwater or
desalinated water. Most people use three types of
water
Application of charges has made public aware of
conserving water
Desalination outside Male’
Most widely used in the resort islands which have
their own desalination plants
Besides the resorts most densely populated island
R. Kandholhudhoo (4.40 hectares in area) has a
desalination plant
50m3/day plant costs US $102,000 for purchase,
transport and installation
Household connections are not provided but water
is available from a tap bay
Desalination in Kadholhudhoo
Cost for filling 20 litre container is US $0.16
therefore cost per m3 is US $7.84
Tariff covers cost of operations and routine
maintenance but not for replacing membranes
which can be very expensive
Although the capital cost was met by government
this is not being recovered
Summary: Maldives
experience with desalination
Desalination has been a success in Male’ –
economies of scale and ease of operation and
maintenance
Since charges were introduced in 1996, supply
has been able to meet demand
A reliable and safe source of water – no
epidemics of waterborne disease since its
introduction
Summary: Maldives
experience with desalination
Desalination in rural islands has had some problems
Difficult to operate and maintain
Cost recovery difficult on a small scale
Level of service has to differ from Male because of difference
in income levels
Demand dependent on availability of rainwater
Reliance on imported fuel and spare parts is a risk
Alternative policies for sustainable development are
sought
Policies for the sustainable
development of water
resources
Increase household and community rainwater harvesting in
the rural islands
Pilot new schemes such as community groundwater
systems (infiltration galleries)
Improved land use planning and introduction of
groundwater protection zones
Protection of groundwater quality through improved
sewage treatment and disposal
Improvement of degraded groundwater resources
Desalination where necessary in most densely populated
islands
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