WATER SHORTAGE MANAGEMENT AND
ADOPTATION TO CLIMATE CHANGE IN MALDIVESYour Name : Fathmath Shaushan MoosaYour ID (MEE 15626 )Supervisor: Prof. Kuniyoshi Takeuchi
Dr.Akira Hasegawa

ABSTRACT
Every years from January to April, Maldives experiences a dry period. It is in this period, the country
faces a shortage in drinking water. To assess the problem, the precipitation, roof area, water storage
capacity and population data was used in the studies. From the results, we came to an understanding thatfor the present time, increasing of the storage tanks can solve the problem. As there is enoughprecipitation in the rainy season, we need more storage space to store rainwater for the dry season.
The Future climate studies were done by using MRI-AGCM3.2S with RCP 8.5 scenario (greenhousegas emission scenario, which has a high impact in the climate change). Daily precipitation data for futuredata between the years 2075 - 2099 was used. It showed an increase in the future rainfall but at the sametime an increase in water shortages by 24% was also predicted in the future.
The future climate data was again studied further by SPI and cSPI approach. It showed that there will
be an increase in the extreme events in the future. The extreme wetness as well as extreme water shortage
were increasing. Implicating that there will be severe floods and severe water shortages in the future.
According to the findings and results of these studies, we came up with some recommendations, which
can be implemented by the government of Maldives and practiced by the inhabitants. There countermeasures can be used to eradicate water shortages and to reduce flood risk in the Study area Noonu Atollas well as other atolls of the country.
Keywords: Rainwater harvesting, Water shortage, Climate change, Extreme events, SPI & cSPI
approach
INTRODUCTION
Water scarcity is a major problem in the world. Around 1.2 billion people in the world lives in areas ofphysical scarcity of water. (UNDESA, 2005). Because of the geography and topography of the country,
it can be said that the Maldives is a country of physical scarcity of water. As it is, a small island nation
made up with 1192 small coral islands, which is only 1% dry land out of its 90,000 km2 area of thecountry. The country experiences equatorial tropical climate with an evenly distributed rainfall of 1924mm of average annual rainfall. Out of the two monsoons, southwest monsoon has a wet period from
May to November and the northeast monsoon has a dry period from January to March. It is in this dry
period, the shortage of water is experienced throughout the country every year.
The main freshwater resource in Maldives occurs as groundwater embedded in basal aquifers, generally
unconfined in nature, and extending below sea level in the form of a thin freshwater lens. (Maldives
Water and Sanitation Authority, n.d.). These aquifers are vulnerable to excessive abstraction as well as
contamination due to human activities such as pollution, improper sewage disposal, and saltwater
intrusion owing to the freshwater-seawater interaction (Ministry of Housing Transport and Environment
Government of Maldives, 2009). Because of vulnerability and high chance of contamination,
groundwater is no longer a reliable source of drinking water. Another source of freshwater in Maldivesis desalinated water, which is an expensive source of water for the population. Many technical issues
1that can lead to a huge water shortage in the country face the source. (e.g. the 04th December 2014 Male’water crisis.)
For these reasons, rainwater harvesting, which is practiced in the country for a long time is the mostconvenient and economical method of fresh water source in Maldives. The Maldives practice a roof top
rainwater harvesting technique. It a low cost technique to collect domestic rainwater. Yet, precipitationis characterized by extreme variability and extreme events that propagate natural disasters such as
floods, droughts, and storm surges. It gives a challenge in managing the rainwater to make it available
all year round even in the dry season. Hence, the need to develop a plan thorough understanding of thetrends and frequencies of such disasters that may cause water scarcity is in high priority .Apparently,
rainfall is threatened by the climate change phenomena, which is increasing temporal and spatial
variability in the patterns, amount, and distribution.
THEORY AND METHODOLOGYThis research work is mainly focused on assessing the water shortage and frequency and find thecountermeasures for water shortage in the Noonu Atoll of Maldives. In order to achieve this, the study
is divided into different phases. The first phase is to study the existing rainwater harvesting system inorder to find out the gaps in the system and to come up with improvements that needs to be introduced
into the system. This will be followed by a study, the historical rainfall data for this, Hanimaadhoostation rainfall data for the period from 1994-2015 will be used. The analysis will involve use ofStandardized Precipitation Indices (SPI) in order to assess the frequency of shortages in water over theyears and also water shortage and floods. We developed a model “Water Shortage Assessment Model”
to assess severity of water taking into consideration the precipitation, roof area, and storage tank capacity
and water demand. By the results we get from this model, we can understand how much water is being
utilized and how much water is being thrown away as waste. After calibration and validation of themodule, and comparing the results we can identify the root cause of water shortages in Noonu Atoll. It
was also used to find the optimum storage needed for the atoll as well as the capacity needed for thedifferent households as per the resident population. GCM data (General Circulation Model or Global
Climate Model) was used to for the study of climate change in the area and predicting the future rainfall
and water shortages. The data was based on MRI-AGCM3.2S, an atmospheric global climate model
covering the whole world with spatial resolution of 20-km grid cell developed by Metrological ResearchInstitute (MRI) of Japan Metrological Agency (JMA) The set of data that are to be applied for thisstudies are the daily precipitation data from year 1979 to 2003 and the future precipitation data that isfrom year 2075 to 2099. We considered using RCP8.5 scenarion in this study. It corrusponds to thepathway with the highest green house gas emission. Which has a high impact on climate change. (Riahi
et al, 2011). Historical water shortages and floods were quantified using standardized indices of SPI.
Future water shortages and floods were quantified using standardized indices of comparative Standard
Precipitation Index cSPI approach. The same data set was used on the “Water Shortage Assessing
Model” estimate the future water shortages, its frequency and severeness. Recommendations was made,on ways that can eliminate water shortages in the Noonu Atoll according to the results that was obtained
from the models used in the studies.
DATA
The study area for this research is Noonu Atoll also known as Miladhunmadulu Dhekunuburi, which isone of the 26 Atolls, the country corresponding to the southern section of Miladhunmadulu Atoll andthe northern most atoll of Maldives. Noonu Atoll is a code letter assigned to this atoll in the present
administrative division. There are 71 islands in this atoll while 13 are inhabited islands. The total2

population of this 13 island is 11,229 according to 2014 census. The
estimated total land area of this 13 island is 403.711 km2.
Most of the other important data collected for these studies
include, observed precipitation data from five main stationsof the country, roof area, storage capacity, population,
Islands area. Most of these data are collected directly fromgovernment departments, the published materials, orinternet and are sought after extensively.
To understand the future impacts of climate change on
precipitation was studies by using GCM data. The data isbased on MRI-AGCM3.2S, an atmospheric global climate
model covering the whole world with spatial resolution of 20-km gridcell developed by (MRI) of (JMA) (Ryo MIZUTA, 2012). The set of data that are to be
applied for this studies are the daily precipitation data fromyear 1979 to 2003 and the future precipitation data that is Figure 1: Study area (Noonu Atoll)from year 2075 to 2099. We considered using RCP8.5
scenarion in this study. It corrusponds to the pathway with the highest green house gas emission. Whichhas a high impact on climate change. (Riahi et al, 2011)
RESULTS AND DISCUSSION

1
23
45
67
89
111
133
155
177
199
221
243
265
287
309
331
353

Amount of water(ltr) Millions

Amount of water (ltr)
Millions

Results of this study is based on the “Water Shortage Assessing Model” that was used to study the water
shortages and frequencies. The observed
40.0
QT water supplied
precipitation data from Hanimaadhoo station
overflow / spill overfor the study area Noonu Atoll was used. In the
20.0
first section we concentrated on 2011 water
shoratage
shortage, since it was the year with the least
average monthly rainfall for the first four0.0months of the year and hence the year with themost severe water shortage in the recent days.
MonthsFigure 2 shows the amount of water that wasused from the water stored in the tank (orange Figure 3: Water availability, overflow, andshortage graph for the year 2011bar) and the water in shortage (red line) and theamount of water that was spilled out (blue bar)due to less storage capacity. Although there is no / less rainfall in the first four months of the year, water
shortage started to occur in the month of January. This is because of the rainwater that was collected
and stored in last months of the year (2010).
It showed that there was a water shortage of
20.0
14%. Only 27.8% of rainwater was
15.0
harvested, the other 72.2% was spilled out
10.0
because the storage tank was full at the time
5.0
of rainfall.
0.0
The model was again used to determine theoptimal storage capacity that was needed to
Number of days
avoid the water shortage for the year 2011.
Figure 2: Daily water level in take after the tank
The same whether condition (precipitation capacity has been increased using the “Water
data) was used and the storage volume was Shortage Assessing Model” for the year 2011changed several times so that we can get a 0%
3

water shortage for the year 2011. With a storage capacity of 16,859,000 liters, the water shortage wasobserved as “0%.” With the amount of increase in storage capacity 32.9% of rainwater was harvested,
the other 67.1% of rainwater was spilled out. And with the increase in storage capacity the water
shortages for the past years was also brought down to 0%.
Since rainwater, harvesting is an individual household effort, the optimal rainwater harvesting tankcapacity and roof area needed for the individual households are also calculated. Assuming that the water
demand is 15 L/d/p, and using the rainfall data from 1979 to 2015 (36 years). The calculations weremade and the results are as in Table 1.
Table 1: Storage capacity and roof area need for the households depending on the size of thefamilyHousehold size
(person)
4
6
7
8
10

Roof
(m2)

Area
30
30
35
35
40

Storage tanksize (Liters.)
5000
8000
8000
10000
20000

Water demand(L/d/p)
15
15
15
15
15

Percentage stored
in the tank
45%
68%
59%
77%
68%

Percentage
spill over
55%
32%
41%
23%
32%

1979
1980
1981
1983
1984
1985
1987
1988
1989
1991
1992
1993
1995
1996
1997
1999
2000
2001
2003

Indices

Rainfall in mm

It shows a roof area between 30 m2 and 40 m2 and storage tank capacity from 5000 Ltrs to 20000 Ltrs
that can be used to supply a household size of 4 to 10 people. The percentage of water that is collectedin the tank and the percentage of water that is300
lost due to spillover due to the size of thecatchment area and storage tank size can also
200
be seen in the table. For example a household100
of 7 people, it would require a storage capacity
SFA
Observedof 8000 Ltrs capacity with a roof area of 35 m2
0
to go through an year without running thestorage tank dry. An amount of 59% ofMonthsrainwater that is caught on the roof will be
Figure 4: Monthly average rainfall – SFA futurecollected and stored in the storage tank.
and observed
To understand the future impacts of climatechange on precipitation was studies by using GCM data (Global Climatic Model). To do this theobserved rainfall data for the Hulhule station was compared with the downscaled MRI-AGCM3.2S data
under the current climatic condition. A simple bias correction was applied to the AGCM data to reduce
the uncertainty of the data that may come from3
underestimation. The PGF data was used to bias
2
correct the MIRI-AGCM3.2S data present data
10
from 1979 to 2003 and future data from 2075-1
2099.
-2
To analyze the future precipitation, the future-3(2075-2099) rainfall data for MRI-AGCM3.2S
data was studied and compared with the currentYearobserved data from (1975-2003). Figure 4
Figure 5: 3-month SPI of Hulule stationshows an increase in the future rainfall from
1925 mm/y (present) to 2093 mm/y for the future yet the dry season from February to March remains
as the driest months of the year.

4

2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096

Millions

2075
2076
2077
2078
2080
2081
2082
2083
2085
2086
2087
2088
2090
2091
2092
2093
2095
2096
2097
2098

Indices

SPI and cSPI approach was used to analyse the climate change assesment at 3-month timescale. It canbe used to monitor the condition of drought (in this study will refer to as water shortage) or wetness ina variety of time scale. (World Meteorological Organization, 2012)
The SPI values indicated by the negative values mean a drier period and positive values means wetter
periods based on climate conditions. In the graphs, the moderate dryness is shaded in light yellow while
severe dryness is shaded in orange. Moderate3
wetness in shaded in blue and severe wetness
2
1
is shaded in light blue.
0
The figure 5 shows the SPI of 3-month time-1
scale for the observed precipitation data for-2-3
Hulule station.
For predicting the future water shortage andYearwetness, we used the cSPI approach for the
climate change assessment. In estimating Figure 6: 3-month cSPI (2075 – 2099) of Hulule
future climate and precipitation (Figure 6), we
substitute the observed precipitation data with the future climate data for Hulule station, with MRIAGCM3.2S in future 2075-2099. Referring to the SPI and cSPI data for the three months’ time scale wecalculated the probability of water shortages and wet conditions in the future with comparison to thepresent climate condition. By comparing the SPI and cSPI data, we can see that the future extreme eventsof both water shortage and wetness are increasing. Although the severe water shortages that we face
every twenty years now Table 2: Probability of water shortages and wetness in future withwill be less in the future, comparison to the present climate
SPI Values
Category
Present
Futurethis is replaces by an
Condition
Condition
extreme water shortage by
Extreme wetness
1/42 years
1/25 years≥ 2.0
once in every twenty seven
1/21 years
1/12 years
1.50 to 1.99 Severe wetness
years.
Mild - Moderate wetness
1/7 years
1/6 years
0 to 1.49
Mild - Moderate water shortage 1/1 year
1/1 years
0 to -1.49
However, in case of
Severewater
shortage
1/20
years
1/42 years
-1.50
to
-1.99
wetness the severe andExtreme water shortage
1/75 years
1/27 years≤ -2.0extremeeventsareincreasing in the future. The probability of having a severe wetness or an extreme wetness in the future
is more, compared to the present climate.
To estimate the future impacts of the water shortages, climate data of MRI-AGCM3.2S data for thepresent climate (1979-2003) and the future
10.0
climate (2075-2096) was applied to the“Water shortage assessing model.” Assuming
5.0
the same population, storage capacity, androof area. It shows (Figure 7) an increase of
0.0
24% of the future water shortage from year
2075-2096. Although there was an increase in
QT water supplied
shoratage
the precipitation of the future climate data, we Figure 7: Monthly water supply and shortage withcan see an increase in the water shortages as future data (2075-2096)
well. This maybe caused due to the extreme
events, which was seen in the SPI and cSPI analysis.
RECOMMENDATIONAs the country has a high amount of precipitation in the rainy season, the best way to overcome thewater shortage problem is to Increase the storage capacity of the islands. Therefore, that in the time of5the dry season there will be enough water for consumption. One of the reason why people tend not tohave a higher capacity of storage tanks is due to lack ground space. Since the storage tanks takes a lotof space from the less available space of ground. To address this issue, it is recommended to encourage
people to have more of underground water tanks below the house. So that the land space can be used aswell as the required amount of storage capacity can also be achieved.
Desalination plants can also be an alternative for the water shortage problem. Especially for the islands
with a higher population density and where ground water is not an alternative for rainwater. However,
it is recommended to encourage people to harvest rainwater. Since desalination of water is a costlier
method. Therefore, we would suggest having at least one desalination plant per atoll so that the transport
cost of water will be reduced than the present situation.
After a heavy rainfall, it is common to see stagnating water in the islands. At present, the water ispumped into the sea. It is recommended to have Infiltration pits, basins, and injection wells so that thiswater can be used to infiltrate recharge the aquifer.
ACKNOWLEDGEMENTS
I would like to express my gratitude to my supervisor Professor Kuniyoshi Takeuchi, advisor toInternational Centre for Water Hazard and Risk Management (ICHARM) for his unconditional
guidance, support, suggestions, and patients through my individual studies and development of thismaster’s thesis. I am also thankful to Dr.Akira Hasegawa for sharing his time, knowledge, and advice
and suggestions in the studies as a sub supervisor.
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