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Current subsidies to residential water users in Oman are estimated at USD 314 million/y. This study estimates the demand function for residential water in Muscat, Oman, for households living in villas. A two-stage least squares econometric model with lagged average water price was used with socio-economic variables. Price elasticity for residential water in Muscat was estimated as –2.10. This high price elasticity is explained by the large proportion of water used for outdoor purposes. This study indicates that it may be possible to manage water demand in Muscat through modifying the price of water and reforming subsidies for residential water.
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International Journal of Water Resources Development
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Demand function estimate for residential water in
Hemesiri Kotagama, Slim Zekri, Rahma Al Harthi & Houcine Boughanmi
To cite this article: Hemesiri Kotagama, Slim Zekri, Rahma Al Harthi & Houcine Boughanmi
(2016): Demand function estimate for residential water in Oman, International Journal of Water
Resources Development, DOI: 10.1080/07900627.2016.1238342
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Demand function estimate for residential water in Oman
Hemesiri Kotagamaa, Slim Zekria, Rahma Al Harthib and Houcine Boughanmia
aDepartment of Natural Resource Economics, College of Agricultural and Marine Science, Sultan Qaboos
University, Muscat, Sultanate of Oman; bEconomic Researcher, Ministry of Manpower, Muscat, Sultanate of Oman
Current subsidies to residential water users in Oman are estimated
at USD 314 million/y. This study estimates the demand function for
residential water in Muscat, Oman, for households living in villas. A
two-stage least squares econometric model with lagged average
water price was used with socio-economic variables. Price elasticity
for residential water in Muscat was estimated as –2.10. This high
price elasticity is explained by the large proportion of water used
for outdoor purposes. This study indicates that it may be possible
to manage water demand in Muscat through modifying the price of
water and reforming subsidies for residential water.
The rapid and signicant increase in demand for residential water in Oman is driven by
increasing population growth, improvements in the standard of living (associated with
increased household income) and rapid economic development, which has attracted large
numbers of migrants for employment (Alshawaf, 2008). The Public Authority for Electricity
and Water (PAEW, 2011) expects demand for residential water in Oman to reach 630 million
m³ by 2025, from 215 million m³ in 2011. The Governorate of Muscat (the capital of Oman)
utilizes 148 million m3/y of residential water, which represents 69% of total water usage in
the country. Because more than 90% of the residential water supply is desalinated, the
increase in water demand leads to increased dependence on non-renewable energy for
desalination and increased government subsidies. Residential water prices are subsidized
in Oman and other Gulf Cooperation Council countries; this has led to higher demand for
water, which has been primarily addressed through supply-side management (Abderrahman,
2000; Dawoud, 2011; Ouda, 2014).
The price of water in Oman is administered in a two-block structure which has not
changed since 1980, even though cumulative ination reached 48.8% between 2000 and
2013. The price is USD 1.14/m³ for water consumption of less than 23 m³/month and USD
1.43/m3 for consumption greater than 23 m³/month (OIFC, 2013). Government subsidy of
water supplies has reached 61.5% of the total cost of production and supply of water; this
subsidy totalled USD 314 million nationwide in 2012, with a 6% annual rate of increase. The
subsidy for water supplies in the Muscat Governorate reached USD 175 million in 2012. The
© 2016 Informa UK Limited, trading as Taylor & Francis Group
Water demand; residential
uses; outdoor uses; water
price elasticity; Oman
Received 12 January 2016
Accepted 10 September 2016
CONTACT Slim Zekri
average subsidy per residential connection exceeded USD 1000 in 2012 (PAEW, 2012).
Paradoxically, households not connected to the urban water network pay higher prices for
water supplied by bourses and receive lower quality of service. On average, each household
pays USD 100 per/month for water supplied by bourses, while a family that is connected to
the urban water network receives greater volumes with higher reliability and pays approx-
imately USD 87 per/month. Thus, it is evident that households are willing to pay more for
water based on scarcity values.
Since May 2008, households have paid for sewage disposal, in addition to residential
water supply, in districts connected to sewage treatment plants (Zekri, Boughanmi, & Zairi,
2010). The service charge for sewage disposal is included in the same bill as the charge for
residential water as one total amount, thus appearing as a higher price for water. The sewage
disposal charge is USD 0.40/m3 of residential water consumed, regardless of the volume of
sewage disposed of (Haya, 2013). This charge is far below the cost of wastewater treatment
(Zekri et al., 2010). In fact, the subsidy for sewage treatment in the Muscat Governorate was
approximately USD 29 million in 2012 and will increase rapidly as additional residences are
connected to the sewage disposal network. The total subsidy to the water sector (for desal-
ination and sewage treatment) in the Muscat Governorate reached USD 204 million in 2012.
The cost of water supply and sewage treatment in Muscat reached USD 5.4/m3 on average
per household, while each household paid only USD 1.85/m3, for a 66% subsidy. These gures
do not take into account the fuel subsidy provided to desalination plants or the environ-
mental costs of brine and chemical disposal in the sea by desalination plants.
Oman continues to increase the supply of desalinated water to respond to growing
demand for residential water, and few if any initiatives have been undertaken to manage
the demand for residential water. A lack of information exists regarding the primary variables
aecting demand for residential water, and this lack of information hinders the ability to
design and implement strategies to manage demand for water. This article will bridge the
information gap and support the process of decision making to manage increasing demand
for residential water. This study estimates the residential water demand function for house-
holds living in villas (individual houses with garden space) in the Muscat Governorate; villas
represents the primary type of residential building in the city. The second section provides
a review of previous studies regarding estimation of the demand function for residential
water use, and the third section provides an explanation of the research method adopted
and the econometric model utilized to estimate the demand function for residential water.
The fourth section presents and discusses the results. The conclusions are presented in the
nal section.
Literature review
Determinants of water demand. Price of residential water is a principal determinant of demand
for residential water. Increasing block rate pricing introduces some diculties in econometric
model specications. Hussain, Thrikawala, and Barker (2002), and Mieno and Braden (2011),
utilized the marginal price with a dierence variable to deal with the non-linearity and
discontinuity of price imposed by increasing block pricing. The dierence variable was
dened as the dierence between actual total payments and the total amount consumers
would pay at the marginal price. Other specications of the price of water include average
price (Domene & Saurí, 2006; Kenney, Goemans, Klein, Lowrey, & Reidy, 2008; Musolesi &
Nosvelli, 2007), marginal price (Mieno & Braden, 2011; Olmstead, Michael Hanemann, &
Stavins, 2007), and lagged average price (Arbues, Barberan, & Villanua, 2004; Arbués &
Villanúa, 2006).
Non-price determinants of demand for residential water considered in most studies
include household income, number of household members, ages of household members,
gender structure of a household, type of building structure, and other factors such as rainfall
and temperature (Corbella & Sauri Pujol, 2009).
Certain studies have demonstrated a positive relationship between household income
and the quantity of water consumed (Domene & Saurí, 2006; Harlan, Yabiku, Larsen, & Brazel,
2009; Schleich & Hillenbrand, 2009). However, studies have also reported that high-income
households are less sensitive to changes in the price of water (Mieno & Braden, 2011).
Schleich and Hillenbrand (2009) determined that income elasticity is positive and declines
as income increases. According to certain studies (Arbues et al., 2004; Gaudin, 2006; Hussain
et al., 2002; Olmstead, 2007), conducted in various locations representing a wide range of
water development status and socio-economic conditions, estimates using the log-log
demand function indicate that income elasticity of residential water is low and ranges
between 0.074 and 0.55.
Although studies have conrmed that households with more members consume more
water than households with fewer members (Arbues et al., 2004; House-Peters, Pratt, &
Chang, 2010), consumption per capita declines with increased numbers of household mem-
bers (Arbues et al., 2004; Schleich & Hillenbrand, 2009). It has been determined that sin-
gle-family houses (villas) consume more water, due to greater outdoor water use (Domene
& Sauri, 2006). Mukhopadhyay, Akber, and Al-Awadi (2001) and House-Peters et al. (2010)
indicated that outdoor water use depends upon the outdoor space and the level of education
of household members. In addition, these scholars demonstrated that ownership of a swim-
ming pool had a signicant eect on the quantity of residential water consumption.
Price elasticity of demand for residential water. Most studies (Arbues et al., 2004; Arbués &
Villanúa, 2006; Gaudin, 2006; Hajispyrous, Koundouri, & Pashardes, 2002; Hussain et al., 2002;
Martinez-Espineira, 2002; Musolesi & Nosvelli, 2007; Olmstead et al., 2007) indicate that
demand for residential water is price inelastic, with estimates ranging from –0.029 to –0.80.
A few studies (Klaiber, Smith, Kaminsky, & Strong, 2014; Yoo, Simonit, Kinzig, & Perrings, 2014)
have estimated high price elasticities, when outdoor uses are considered, ranging from –1.57
to –3.33. Olmstead et al. (2007) indicated that the demand for residential water is more price
elastic when block pricing is used than when uniform pricing is used.
Method of estimating the demand function of residential water. The most common econo-
metric model used to estimate the demand function for residential water when increasing
block prices are in place is the ordinary least squares (OLS) model. However, use of the OLS
model has been criticized by certain authors due to the endogeneity issue (Arbues et al.,
2004; Gaudin, 2006; Kenney et al., 2008; Mieno & Braden, 2011; Olmstead, Hanemann, &
Stavins, 2005).
Olmstead et al. (2007) tested dependence of price elasticity on the price structure. A
discrete continuous choice model was used to estimate the price elasticity for water, for
both increasing block prices and uniform marginal prices. Hussain et al. (2002) estimated
water demand for industrial, residential and commercial sectors of urban areas in Sri Lanka
using monthly data for water consumption at the country level. OLS was utilized to estimate
the model with linear and log-log forms. The log-log functional form performed better than
the linear form according to the signs, signicance, reliability and adequacy of estimated
coecients. Arbues et al. (2004) concluded that consumers react to the lagged average price.
Arbués and Villanúa (2006) utilized dynamic panel data for households to estimate the
demand function for residential water in Spain. This analysis indicated that the linear demand
function was more appropriate than the log-log and semi-log functional forms. Musolesi
and Nosvelli (2007) estimated the residential water demand in a dynamic context in Italian
cities. In the econometric analysis, the generalized method of moments estimator was uti-
lized to overcome the endogeneity issue.
Gaudin (2006) used aggregate cross-sectional community-level data, and estimated water
price elasticity coecients using the OLS and two-stage least squares methods of analysis.
The log-log functional form was utilized because the linear functional form forces price
elasticity to decrease along the demand curve and the log-log form facilitates convenient
interpretation of estimated parameters. Mieno and Braden (2011) used municipal panel data
on water consumption and a xed eect model to reduce bias that could be caused by OLS
because data regarding swimming pools and lot sizes for each municipality were not avail-
able. The data were aected by autocorrelation, which was addressed by using Newey-West
consistent estimation for the variance-covariance matrix of coecients. Polycarpou and
Zachariadis (2013) analyzed residential water demand in Cyprus, using a two-stage least
squares model with an instrumental variable in two stages. The rst regression was between
the suspected endogenous variable and other exogenous variables, which are not related
to the error term. Then the predicted value of the endogenous variable obtained in the rst
stage was used in the second stage as an exogenous variable in the OLS regression.
Research method
This study estimates the demand function of residential water for two districts in the Muscat
Governorate: Al-Seeb and Al-Qurm (Figure 1). These two districts represent households with
dierent socio-economic characteristics. Al-Qurm includes high-income households, and
Al-Seeb represents middle-income households. The dominant building structure in the
Muscat Governorate is the villa vis-à-vis apartment. Villas are singular houses that include a
garden space. The sample includes villas exclusively. The monthly residential water con-
sumption per household and the amount paid for residential water and sewage disposal
services were collected from the water billing company. The sample framework included a
list, provided by the company, that included homeowners’ names and addresses of house-
hold water users. In addition, the list contained monthly data on the quantity of water con-
sumed and payments made by the households from January 2010 through December 2012.
The sample was a stratied random sample. Households were stratied as either (1) house-
holds that pay for both residential water and sewage disposal, or (2) households not con-
nected to sewage disposal network, which pay for residential water only. Thus, for an identical
amount of residential water used, the households in (1) paid higher prices for water than
households in (2). The sample included 266 households, of which 144 were in (1) and 122
were in (2). A questionnaire was utilized that included questions regarding household char-
acteristics, indoor water use and outdoor water use. The survey was conducted from 1 July
1 through 21 August 21 2013. Trained interviewers visited the villas and conducted personal
Consumers are billed monthly for water use. However, in this article quarterly averaged
data regarding water use and payments were utilized. In fact, it has been observed that
many consumers pay their bills late, which might aect water consumption in the following
months. The econometric model utilized for this study estimates the demand function for
residential water use as:
Q = volume of water consumed (average of three months, in m3)
LAP = lagged average (three-month) price of water consumed, in OMR/m
(OMR 1 = USD
2.6), calculated by dividing the total value of the water bill by the quantity of water
I = monthly household income (OMR/month)
D = dummy for water price blocks: D = 0 if quantity of water consumed was less than
23 m³/month; D = 1 if quantity of water consumed was more than 23 m³/month
HHM = number of residents in the household
AREA = extent of irrigated area in the garden (m2)
POT = number of potted plants
MIRR = use of modern irrigation system in the garden (dummy variable,
yes = 1, no = 0)
CAW = car washes per week (times per week each car is washed, multiplied by number
of cars)
SPOOL = swimming pool in household (dummy variable, yes = 1, no = 0)
ε = error term.
ln (CAW)+∝
Figure 1.Location of the Seeb and Qurm Districts in Muscat, Oman.
Results and discussion
Figure 2 shows the quantity of water consumed and price paid by households included in
the sample. Certain elements of the data do not align with the basic demand theory of an
inverse relationship between price and quantity of water consumed. These households pay
only for residential water use. Thus, it is observed that at very low water prices, households
are not responsive to water prices. The data elements that align with the basic demand
theory correspond to households that pay for both sewage and residential water and are
wealthier than the previous group. Households connected to the sewage disposal network
pay USD 0.62/m3 more than households not connected, given an equal quantity of water
consumed. Consequently, the econometric analysis included only households that pay for
both residential water and sewage (144 observations). Because data were collected over
three years, 12 data points were available for each household, for a total of 1728 data points.
The estimated correlation matrix of the independent variables indicated a high correlation
between number of potted plants, size of the irrigated area and use of a modern irrigation
system. Thus, only the number of plotted plants was retained as an independent variable.
Endogeneity was veried by the Hausman (1976) test based on the method suggested by
Hill, Griths, and Lim (2008). The calculated statistic for the Hausman test was –26.27 and
was highly signicant at the 5% level, indicating endogeneity between the price variable
and the error term. Therefore, the lagged average price was considered the most appropriate
model to estimate the water demand function. To overcome the problem of endogeneity,
certain studies have applied a two-stage least squares model using the lagged average price
Figure 2.Relationship between water price and volume of water consumed.
(Gaudin, 2006; Polycarpou & Zachariadis, 2013), because the lag eliminates the endogeneity
(Arbues et al., 2004; Arbués & Villanúa, 2006). The study described in this article utilized a
lagged average price to estimate the demand function for residential water.
The demand function was estimated for four functional forms to evaluate the best model
t: linear, log-linear, linear-log and log-log. The log-log functional form provided the best t
to the data, with the highest coecient of determination (R
), and its estimates are provided
in Table 1. The log-log functional form has also been used in certain residential water demand
studies (Gaudin, 2006; Hussain et al., 2002).
The price variable possesses a negative sign and is highly signicant, with an estimated
coecient of –2.10, indicating that the demand for residential water is price elastic. The
estimated price elasticity of –2.10 for household demand of residential water falls within the
range of price elasticities of –0.081 to –3.33, as per past studies. This high elasticity for house-
holds living in villas is due to the use of a signicant portion of the water for ‘non-essential’
outdoor purposes such as irrigating gardens (45% of households), washing cars (40% of
households) and lling swimming pools (6% households). Use of water for these non-
essential purposes could be reduced if prices increase in contrast to essential water use for
domestic purposes. The variables for household income (I), frequency of car washing at
home (CAW), number of members in the household (HHM), price block (D1), number of
potted plants in the garden (POT) and presence of a swimming pool (SPOOL) are all statis-
tically signicant and aect the demand for residential water. In addition, all variables possess
the expected sign. The elasticity of the total number of members in the household is 0.056,
indicating that increase in water consumption is less than proportional to an increase in the
number of residents in household. These results are supported by the studies of Arbués and
Villanúa (2006), and Schleich and Hillenbrand (2009). In alignment with March and Sauri
(2010), this study has demonstrated that the presence of a swimming pool and use of water
for garden irrigation are signicant variables aecting household water demand. As would
be expected, the frequency of car washing at home was also signicant in determining the
quantity of water use.
The average annual water consumption per household was estimated as 519 m3/y for
the Al-Qurm District and 440 m3/y for the Al-Seeb District. The daily per capita average
consumption was estimated as 0.289 m3 and 0.173 m3 for Al-Qurm and Al-Seeb Districts,
respectively. The average per capita consumption for the entire sample was 0.197 m3/day,
much more than the international average of 0.090 m3/day. On average, payment for water
(residential and sewage disposal) represented 3.8% of the total income of a household. The
Table 1.Estimates of the log-log lagged average price model.
**Significant at 5% level.;
***Significant at 1% level.
Variables Coecient Std. error t-Statistic
Intercept 1.510 12.90 12.90
LAP −2.10*** −13.08 -13.08
I0.040** 2.62 2.62
CAW 0.037*** 3.42 3.42
HHM 0.056** 2.68 2.68
D1 1.110*** 41.29 41.29
POT 0.048*** 5.77 5.77
SPOOL 0.190*** 4.23 4.23
R2-squared 0.700
S.E. of regression 0.396
F-statistic 527.827
estimated net annual subsidy was USD 1846 and USD 1565 per household for Al-Qurm and
Al-Seeb Districts, respectively. On average, this is equivalent to a subsidy of USD 3.56 per m3
of water.
Total elimination of water subsidies in Oman would result in a 195% increase in the price
of water, from USD 1.83/m3 to USD 5.4/m3. Such a substantial price increase is not politically
feasible; therefore, water price reform for the elimination of subsidies should be implemented
gradually. Our econometric model suggests that a 10% increase in the price of water will
lead to 21% less water being consumed, for annual water savings of 109 m3 per household.
However, this model cannot be used to predict the quantity of water saved with a total
elimination of subsidy, as the price increases in this case by 195%, and this is substantially
beyond the data range used to generate the econometric model. Furthermore, a ban on
irrigation of gardens may not be operationally feasible considering the high transactional
cost of implementation. However, higher freshwater prices may encourage households to
reduce wasteful water use and provide an incentive to recycle domestic grey water for garden
irrigation (Ahmed, Al-Buloshi, & Al-Maskary, 2012).
Conclusions and recommendations
The demand for water in the Sultanate of Oman has increased faster than supply. This increas-
ing demand is associated with population growth, rural-to-urban migration, rising standard
of living and growth in the industrial and service sectors. The sultanate has adopted a sup-
ply-side approach that consists of increasing the desalinated water supply, while few or no
strategies have been adopted to manage the increasing demand for water. The absence of
information regarding the demand for water impairs the ability of policy makers to utilize
water demand management tools. This article is the rst study to analyze the demand for
residential water in Oman using household-level data. This study is based on a random
sample of households selected from the Al-Seeb and Al-Qurm Districts of the Muscat
Governorate. A random sample of water users was stratied into those paying for both
residential water and sewage disposal and those paying only for residential water. However,
only the data for high-income households that pay for both residential water and sewage
disposal were utilized in the estimation of the demand function for residential water. All
interviewed households resided in villas. The secondary data, regarding the water bill and
volume of water consumed by each household, were provided by the Oman Investment
and Finance Company and PAEW.
A two-stage least squares econometric model with lagged average water price and other
household socio-economic variables was utilized to estimate the demand function for res-
idential water. The econometric results indicate that the lagged average price is a signicant
variable determining demand for water. The demand for water is price elastic, with a price
elasticity of –2.10. This result is consistent with results of international studies that included
outdoor water uses. Other variables utilized in the model included household income, num-
ber of residents in the household, number of potted plants in the garden, presence of a
swimming pool, and frequency of washing cars; all these were determined to be signicant
in determining the demand for residential water. As most of the households use water for
outdoor purposes such as irrigating a garden, washing cars and lling swimming pools, this
use may be adjusted as the price of water increases, thus explaining the high price
The current price paid by households for residential water and sewage disposal and
treatment is estimated as USD 1.85/m
, and the cost of the water supply is estimated as USD
5.4/m3. Thus, the current subsidy is estimated as USD 3.56/m3. There is a need to consider
changes to residential water and sewage pricing in Oman to enhance the nancial sustain-
ability of water supplies and reduce the demand for desalinated water, which depends
entirely on non-renewable fossil fuel for production. Subsidies for the residential water sup-
ply could be targeted exclusively to low-income households. This study demonstrates the
feasibility of reducing residential water demand among high-income households through
increasing the price of water. This price increase will also encourage reduction of water use
for outdoor activities, such as washing of cars and irrigating of gardens, and may encourage
recycling of grey water for outdoor water use.
Disclosure statement
No potential conict of interest was reported by the authors.
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... For instance, water consumption for drinking and cooking was shown to be insensitive to price change, whereas water consumption for car washing and gardening was restricted dramatically by high water prices [18,19]. Climate factors affect residential water use through temperature change and rainfall [20]. Changes in temperature can affect home gardening, drinking water, and bathing, whereas precipitation affects the amount of water used for keeping the environment clean and for washing cars [10]. ...
... For this, many countries have adopted different water charging policies. The price of water in Oman is administered in a two-block structure, and residential water demand is managed by revising water prices and reforming residential water subsidies [20]. The French are a successful example in their implementation of the polluter pays principle (PPP), i.e., paying fees based on the ratio of the amount of fresh water volume abstracted from the aquatic environment and to the wastewater discharged in river; the collected money is returned to water users who are willing to invest in improving the environment [25,26]. ...
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A progressive price scheme (PPS) has been implemented in Shanghai since 2013 in consideration of residents’ ability to pay, and charges are based on the actual water consumption of the residents, in an effort to balance the rational allocation of water resources and the goal of saving water between rich and poor families. In the current work, the effect of the PPS for water use was evaluated based on the water use of 6661 households from 14 communities in Shanghai. It was found that the PPS did not reduce household water consumption when comparing the water consumption per household both before and after the implementation of the PPS policy. To investigate the weakness of the PPS, a principal component analysis (PCA) and a hierarchical cluster analysis (HCA) were conducted to access the relationships between mean household water use and community factors such as housing price, management fees, and the number of parking sites. Moreover, a significant inverted U-shaped curve between housing price and water use was found, which demonstrates that rental households shared by several tenants were the main consumers of residential water, and they were not sensitive to the water price improvement in the PPS due to sharing water prices. Therefore, a proposal was made in this work to increase the proportion of water fee expenditure in the total household income and to use 3% as the benchmark for water affordability. Our results provided a new picture of residential water use in big cities and a method for saving and balancing urban water resources.
... For instance, the brine discharge from desalination plants is increasing the seawater salinity around the discharge areas (Obianyo 2019). On the other hand, the availability of low-cost sources of fossil energy has encouraged Middle Eastern countries to depend almost exclusively on seawater desalination for urban purposes (Kotagama et al. 2016). Similarly, in the USA and Mexico, desalination is part of the solution for the western border areas to meet increasing demand and dwindling supplies (Wilder et al. 2016). ...
... The monetary benefits of improved responses to emergency situations are not accounted for in this paper. Kotagama et al. (2016) estimated that the average annual water demand per household residing in villas is 480 m 3 /year. Thus, the incremental abstraction volume will suffice to provide water for an additional 20,000 to 25,000 households during emergency periods. ...
An increase in groundwater storage in aquifers in arid areas improves water security. Most desalination water production around the globe involves the private sector in the form of “build, operate, and transfer” or “build, operate, and own” agreements. Take-or-pay contracts are the most dominant contracts in the desalination industry. The water utility buys a fixed volume of water from the desalination company over a fixed period of 20 to 25 years. The contract between the two parties is established prior to building the plant to help ensure a profitable investment for all stakeholders. This regularly implies a surplus supply of desalinated water during low water demand periods. Given the absolute water scarcity in arid regions, maximizing the banking of surplus water in an aquifer is considered in this paper. For this purpose, a numerical groundwater flow simulation model, called MODFLOW, and a heuristic multiobjective optimizer, namely, NSGA-II, are coupled to optimize the injection and recovery of seasonal excess desalinated seawater in an alluvium coastal aquifer in Oman. Dual wells are considered for injection and abstraction of the water. The optimal daily abstraction and injection rates are determined by defining a multiobjective optimization framework. The four objective functions considered in this study are maximizing the total volume of desalinated water recharged into the aquifer; minimizing the groundwater losses to the sea; minimizing seawater intrusion by minimizing the maximum seasonal mean drawdown; and maximizing the total benefit from the recharge and recovery of the desalinated water. Analysis of the results revealed that we would be able to use 84% of the excess produced desalinated water (i.e., 8.4 of the 10 Mm3/year) that is currently returned to the sea. The net benefit from storage and recovery ranged between $14.77 million/year and $17.80 million/year. The increasing number of desalination plants at the global level calls for an integrated approach to bank the excess desalinated water and to improve the water security of coastal cities in arid and semiarid regions.
... Additionally, in many arid countries, including Oman, gardens are over-irrigated using subsidized desalinated water (Al-Mayahi 2018;Al-Mayahi et al. 2019). In Muscat, the capital city of Oman, about 45% of the total household water consumption (440 m 3 year −1 ) is used for irrigating villa (household) gardens (Kotagama et al. 2016). Ninety percent of the household water supply in Muscat comes from government-owned and operated desalination plants. ...
... The government subsidizes 61.5% (US$ 314 million year −1 ) of the total cost of water production. The residents pay for this water based on a block tariff scheme; users pay different amounts for different consumption levels: about US$ 1.14 m −3 for the consumption of less than 23 m 3 month −1 and US$ 1.43 m −3 for the use greater than 23 m 3 month −1 (Kotagama et al. 2016). ...
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New water-conserving irrigation technologies are vital in arid countries. We investigated the effects of (i) soil substrates made of Smart Capillary Barrier Wick (SCB-W), consisting of silt loam blocks surrounded by sand-sheathes and irrigated with a sand wick cylinder (WC) as compared to a control (homogenous soil irrigated by the same wick system, HW), (ii) WC diameters (2.54 cm vs. 1.27 cm), and (iii) 2-cm sand mulch layer on soil–water dynamics during wetting–drying cycles. Field experiments with pots and HYDRUS (2D/3D) modeling were performed in two consecutive phases (with and without sand mulch). Analysis of variance at p < 0.05 was used to assess significant differences in measured water contents, θ, between the two substrates. For the wetting/drying cycles, the modeled and measured θ are in satisfactory/tolerable agreement, as documented by the model evaluation criteria, which are within acceptable ranges (the root mean squared error, RMSE 0.01–0.06; Nash–Sutcliffe coefficient, NSE 0.51–0.97, and Willmott index, d = 0.97–1). SCB-W wets the soil substrate about two times faster than HW during the wetting cycles (p < 0.05). Reducing the WC diameter prolonged the wetting time by 1 and 2 days for SCB-W and HW, respectively, the same trend of two times faster wetting of SCB-W compared to HW was maintained. SCB-W showed higher θ storage (by 44.3–52.4%) at the bottom part of the composite than HW (p < 0.05). The sand mulch layer reduced evaporation and resulted in 20 and 38.9% higher θ during the drying cycle for both the bottom and top sensors, respectively, in both substrates (p < 0.05). SCB-W could improve water conservation in home gardens.
... For instance, in Tunisia, "…the richest quintile captured a greater share of the total subsidy (31%) as opposed to the poorest quintile which captured only 11%" (World Bank 2017a). Kotagama et al. (2016) estimated that wealthy families in Oman receive a water subsidy of $1846 per household/year. This shows clearly that the tiered pricing method is totally unfair, while populist voices and many decision-makers still sell it as a policy for protection of low-income classes. ...
... In fact, domestic water consumption in Oman is on the high side with 200 L/cap/day. Kotagama et al. (2016) found that the price elasticity of water for residents in villas is high and is −2.10 due to the outdoor uses. The authors highlighted the possibility of managing water demand in Muscat through modifying the price of water and reforming subsidies for domestic users. ...
The book provides an overview on national policies and regulations related to water resource management in the Middle East and North African countries (MENA), where water scarcity problems are critical. The physical/natural constraints, socio-economic and political circumstances make the MENA region a sort of ‘laboratory’ for natural resource management and particularly water management. The book provides a good comparison on how neighboring countries with quite similar natural constraints and cultures are addressing water problems in different ways. It enlightens water resource specialists on successful experiences around the region and show cases the reforms undertaken in the water sector to meet the challenges posed by urbanization, food security, water pollution and climate change. The book constitutes nine chapters, seven of them with content from the main MENA countries. It starts with an introductory chapter that provides background information on the region’s water resources with descriptive statistics and historical developments of the water sector. It ends with a chapter that summarizes the policy implications and main conclusions on the way forward for sustainable management of water in MENA countries.
... Household amenities and the purpose of water consumption (whether essential or discretionary) also heavily influence household water conservation. Essential uses include cooking, drinking and personal hygiene (Russell & Knoeri, 2020), while discretionary uses, described as 'leisure activities', include swimming, car washing and gardening (Hussien et al., 2016;Kotagama et al., 2017). Recognizing the distinction between discretionary and non-discretionary uses is crucial for identifying effective technologies, incentives or policies for water conservation. ...
In regions with limited freshwater resources, water conservation is crucial for sustainable resource management. This study investigates the links between household attitudes, information sources and water conservation policies in Saudi Arabia. The results reveal that over half the participants agree that water must be conserved, but three-quarters disagree they are obliged to conserve water. Water conservation behaviours were significantly associated with socio-economic characteristics. The study highlights the importance of human attitudes in developing effective water conservation strategies and complementing top-down public awareness approaches with bottom-up programmes using school curricula. This study can inform policymakers in designing effective water conservation policies.
... The unplanned and unsustainable agricultural development during the 1980s resulted in the creation of non-productive farms and increased the water deficit [21,22]. As the population grows and living standards improve, the demand for water resources is increasing, resulting in a daily decrease in the per capita availability of water resources [23]. The majority of Oman's towns and cities are experiencing disorganized and unplanned expansion due to rapid urbanization. ...
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The aflaj systems represent unique irrigation technologies that have been implemented in the Sultanate of Oman. This innovative system, referred to as “falaj” in the singular form, is composed of a sophisticated network of underground tunnels and open-air channels designed to access shallow subterranean water tables, thereby providing water for residential and agricultural use. The aflaj systems have played a significant role in supporting sustainable water resource management in arid and semiarid regions, making a notable contribution to the socioeconomic development of the country. The alteration of land use and land cover (LULC) in arid and semiarid regions can have significant consequences for hydrological systems, affecting the ability of local ecosystems to manage fresh surface and groundwater resources. These changes are often caused by both natural and anthropogenic factors. To investigate the impact of LULC changes on aflaj systems in the northern part of Oman, we utilized satellite imagery, aflaj data, and spatial analytical and image processing techniques within the framework of geographic information systems (GIS) and remote sensing. In the first part of the study, we quantified the changes in LULC and their impact on aflaj systems in seven cities in Oman due to urban expansion. In the second part, we evaluated the effect of LULC on groundwater for four major aflaj between 1985 and 2021. The study area was divided into four primary LULC classifications: vegetation, bodies of water, metropolitan areas, and bare soil. The classification maps demonstrated a high overall accuracy of 90% to 95%, indicating satisfactory performance. Our results revealed a significant reduction in vegetation areas between 1985 and 2021, primarily shifting from bare soil (BS) to urban areas (UAs) and from vegetation cover (VC) to BS, due to the reduction of groundwater resources. Over the four study periods (1985–1990, 1990–2000, 2000–2013, and 2013–2021), the percentages of the total area of Falaj Al-Muyasser, Falaj Daris, Falaj Al-Maliki, and Falaj Al-Khatmeen that transformed from agricultural lands to UAs were 40%, 39%, 32%, and 8%, respectively. Our study highlights the need for appropriate land management and planning to ensure the most effective solutions are utilized to meet social and economic sustainability requirements. In conclusion, our study presents a comprehensive analysis of LULC changes and their impact on aflaj systems over a 36-year period, providing new insights into the potential effects of LULC changes on groundwater resources and offering a basis for informed decision making on land management in arid and semiarid areas.
... Among these were two-stage least squares estimates of water pricing (Musolesi and Nosvelli, 2007;Hillenbrand et al., 2009;Westling et al., 2020) and of electricity pricing (Burke and Abayasekara, 2018;Bordon Lesme et al., 2020). More recently, others adopted the general method of moments for water pricing (Kotagama et al., 2017;De Bonviller et al., 2020) and for electricity pricing (Chanthawong et al., 2016;Waleed and Mirza, 2020). ...
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This research analyses the impact of retailer interventions focusing on the promotion of reusable bags to reduce plastic bag consumption. For this purpose, retail outlet data for March 2018–February 2020 was used. The retail outlet data was analyzed using a panel fixed effects model to evaluate the impact of three treatments on plastic and reusable bag consumption in South Africa. Findings revealed that Treatments 1 (a monetary intervention based on giving reusable bags away for free), and 2 (a non-monetary intervention framed around a plastic-free July campaign), significantly increased reusable bag uptake and reduced plastic bag consumption, while Treatment 3 (a monetary intervention involving a subsidy on reusable bags) increased reusable and plastic bag sales. The findings contribute to the literature on the effectiveness of non-monetary nudges (T2). The latter is more efficient than the monetary incentives (T1 and T3). The results also agrees with the literature on the ineffectiveness of subsidies (T3) for the purpose of discouraging the consumption of plastic bags. The results confirmed that plastic bag consumption is habitual in South Africa. Based on these findings, policy recommendations were made that public campaigns and other behavioral nudges should be considered more effective in addressing the consumption of plastic bags than subsidies on reusable bags. In addition, because of the revealed low level of reuse of both plastic and reusable bags, the use of reminders to reuse bags should be considered and researched in order to modify consumer behavior in South Africa.
... However, PED is known to be high, as many households use significant water for non-essential uses such as garden irrigation and car washing. Households here could reduce usage in response to a higher price (Kotagama, Zekri, Al Harthi, & Boughanmi, 2017), which is important information when considering price rises. ...
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In 2015, increases in the domestic water tariff in Saudi Arabia were met with significant opposition. Although the increases were needed to address the technical and financial sustainability of the service in the context of extreme scarcity and high costs, insufficient effort was made to explain the changes and prepare the public. This paper examines the trade-offs surrounding the design of a domestic water tariff, based on economic theory and global experience, and sets out the competing factors Saudi Arabia should consider when designing a new tariff structure to provide long-term public acceptability while ensuring the service remains sustainable. ARTICLE HISTORY
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This paper provides empirical evidence on the effects of socioeconomic characteristics on residential water consumption. The case of Athens is taken as an example for the empirical investigation, using data from the 2019 Household Budget Survey. Employing ordinary, two-and three-stage least squares, seemingly unrelated regression equations and simultaneous quantile specifications, we found that residential water demand is highly price inelastic. Furthermore, empirical results show that water consumption is positively related to household age while more educated households and unemployed persons seem to follow more environmentally friendly behaviour with respect to water demand. Income, gender, house ownership and population density seem to insignificantly affect residential water demand. Our empirical findings might have important national and regional policy implications in the design of sustainable water demand management.
This chapter examines a series of projects that typify some current trends in the design of the built environment that address the social and economic crisis described in Chap. 1. In all the cases discussed there is a common theme that climate change issues can be dealt with through economic growth and technological development, of which the design of new urban areas and buildings is a part. Designs, from various countries, that are both large and complex are examined, including a suggestion for off-planet living. All are inspected for their contribution to minimising environmental impact. What is revealed is that the designs fall into one of two types. The first are those that solve problems that do not exist and the second are those that tend to make existing problems worse. Exacerbating existing problems is an aspect of increasing complexity, which in turn has been linked to societal collapse. Although designers may see themselves as agents of ensuring a more environmentally aware and viable solution for everyone, this chapter challenges whether some of the results achieve this.
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Changes in water availability, and hence price, are expected to be amongst the most disruptive effects of climate change in many parts of the world. Understanding the capacity of society or consumers to adapt to such changes requires understanding the responsiveness of water demand to price changes. We estimate the price elasticity of residential water demand in Phoenix, Arizona, which is likely to be strongly impacted by climate change. Most existing approaches to the estimation of water demand functions have limited capacity to isolate the effect of price on water consumption where there is little variation in water price. A recent study by Klaiber et al. (2012) attempts to address this issue by using differences in consumption levels, and weather-related characteristics to isolate the price effect on water demand, and by using a constant term in a differenced regression model. We also estimate a differenced regression model, but include direct measures of changes in water prices. This inclusion successfully isolates the price effect on water demand, and enables us to distinguish between the short- and long-run price elasticity of water demand, and hence the short-and long-run adaptation to changes in water availability.
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Saudi Arabia is facing a chronic water-shortage problem. Demand far exceeds the sustainable yield of both conventional and non-conventional water resources. The resulting demand–supply gap is being bridged through groundwater depletion. In this paper, demand–supply gaps for the coming 20 years are projected under three scenarios: optimistic, moderate and pessimistic. Future sustainable water yields are calculated and allocated to projected water demand in the domestic, industrial and agricultural sectors. The study shows that Saudi Arabia will not be able to bridge the demand–supply gap in the near future. Intensive water demand management measures are needed in all sectors to minimize future demand–supply gaps, especially focused on the largest water consumer: the agricultural sector.
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Weekly water consumption data from 48 households in Kuwait were collected over a period of one year. Based on these data, the average per capita water consumption inside a house in Kuwait was estimated to be in the range 182–2018 l/d/person, with an average of 814 l/d/person. Linear regression and neural network models, fitted to the observed data, suggest dependence of the residential water consumption on the number of bathrooms and rooms in the residence, size of the attached garden, income level of the household, atmospheric temperature, relative humidity, and number of people in the residence.
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This paper exploits the seasonal and annual changes in marginal prices for water to estimate the price elasticity of demand by residential households for water. It uses the changes in distributions of water using the census block group levels in response to changes in marginal prices of water for matched months across years. This strategy reduces the interaction effects of outdoor use and demographic fact in determining responsiveness to price. By comparing years that vary in overall water availability the framework can recover measures of how responses to price vary with season and draught conditions. The application is the urban Phoenix metropolitan area.
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The scarcity of water resources and the increasing gaps between demand and available supply in the Gulf Cooperation Council (GCC) countries is a major challenging issue facing the development sectors. GCC countries have extremely dry climates with rare rainfall, high evaporation rates and limited non-renewable groundwater resources. At present all GCC countries except Oman fall in the critical water scarcity category which is about 500 m of renewable water/cap/year. In addition, governmental policies with regard to increasing the level of food self-sufficiency through subsidies and other incentives, have contributed to a major expansion in and unrestricted use of non-renewable groundwater resources. This coupled with a lack of defined policies and strategies geared toward optimizing and managing the scarce water supplies within the GCC region, have contributed to wasteful and uneconomic practices, as well as to the inefficient mining of non-renewable supplies. To meet the present and future water demands of the region the available options are limited to either long distance water transfer and import from other countries or investing in large scale seawater desalination installations. In this paper the economical, technical, sustainability and the political criteria affecting the two alternatives have been evaluated. Economic analysis revealed that the cost of long distance water transfer can escalate to more than 0.83 US$ per cubic meter. When sustainability considerations are taken into account this figure may reach up to 2.35 US$ per cubic meter. While these figures were competitive with the cost of seawater desalination 20 y ago, the situation has been recently shifted in favor of seawater desalination which dropped from 5.5 US$ in 1979 to less than 0.55 US$ in 1999 using the RO technology. It is concluded that sustainable development of GCC countries will depend in the future on large scale desalination. This fast growing technology should replace or at least be considered a viable alternative to presently planned water transfer projects. Expanding desalination capacity in the next 20 y will be possible by building new plants or upgrading the existing facilities in GCC countries. This process, however, will require high economic investment.
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Reducing consumption in affluent urban households is perhaps the most important driver of future natural resource conservation. This article examines how water consumption in individual households is affected by income and determines whether household amenities or attitudes toward community and the environment mediate the effect of income on residential water use, net of other factors. We matched household social surveys, property characteristics, and climate variables with 24 months of individually metered water usage records for single-family houses in Phoenix, AZ. Household income had a positive, significant effect on consumption that was mediated by house size. Irrigable lot size and landscape type also had significant effects on consumption, although attitudes did not. In order to promote environmentally sustainable behavior we must develop better models of the social organization of consumption and encourage affluent households to be more attuned to the water affordances of their lifestyles.
This paper analyses econometrically residential water demand in the three major urban areas of Cyprus, a semi-arid country with medium to high income levels. Water demand turns out to be inelastic, but not insensitive, to prices; price elasticity is less than unity in absolute terms, but significantly different from zero. The analysis further shows that periodic interruptions in household water supply, which were applied as an urgent water saving measure in 2008–2009, did not encourage water conservation among the population. The paper discusses these results, pointing at the need for appropriate water pricing policies and long-term planning in order to move towards sustainable water resource management.