Global Ecology and Conservation 10 (2017) 9–22 Contents lists available at ScienceDirect Global Ecology and Conservation journal homepage: www.elsevier.com/locate/gecco Original research article Sustainable water demand management in the face of rapid urbanization and ground water depletion for social–ecological resilience building Md Arfanuzzaman ∗ , A Atiq Rahman Bangladesh Centre for Advanced Studies (BCAS), H-10, R-16a, Gulshan avenue, Dhaka-1212, Bangladesh article info Article history: Received 13 November 2016 Received in revised form 17 January 2017 Accepted 20 January 2017 Keywords: Water conservation Ground water depletion Optimum water pricing Social–ecological resilience Sustainable water demand management Water resource economics Urban water security abstract Necessity of Sustainable water demand management (SWDM) is immensely higher in the rapidly urbanized mega cities of the world where groundwater depletion and water deficit are taking place perilously This paper focuses on the present condition of water demand, supply, system loss, pricing strategy, groundwater level, and per capita water consumption of Dhaka city, Bangladesh The study founds population growth has a large influence on water demand to rise and demand of water is not responsive to the existing pricing rule adopted by DWASA It emerges that, water demand is increasing at 4% rate an average in the Dhaka city since 1990 and groundwater table goes more than 70 m down in central capital due to extensive withdrawal of water The study suggests an integrated SWDM approach, which incorporates optimum pricing, ground and surface water regulation, water conservation, sustainable water consumption and less water foot print to ease groundwater depletion In order to attain sustainability in water demand management (WDM) the study recommends certain criteria under economic, social and environmental segment to administer the increasing water demand of growing population and conserve the fresh water resources of the world’s mega cities for social–ecological resilience building © 2017 Published by Elsevier B.V This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Introduction Water demand management, ensuring minimum water for daily consumption, water resource planning, and ground water depletion are the common concern in the rapidly urbanized mega cities around the world and the challenge is much higher in the developing countries to address and mitigate such primary water problems In 2014, closely 3.9 billion people, or 54% of the global population lived in cities, and by 2050, two-thirds of the global population will be living in cities, which will generate 55% additional water demand in the world (OECD, 2012; UNDESA, 2012) The future water condition will be impossible to manage unless the world cities are able to address the present water challenges including water security, demand management, conservation, equity, water efficiency and sustainable consumption In household water security index Central and West Asia, East Asia, South Asia, the Pacific and the advanced economies obtained 2.3, 3, 1, 1.5 and respectively Besides, in urban water security index Central and West Asia, East Asia, South Asia, the Pacific and the advanced economies received 1.6, 2, 1.9, and 2.9 correspondingly (ADB, 2013) It appears that, the situation of urban water security index is comparatively worse than the household water security index for all the regions and the condition of South Asia is relatively lower in both categories The existing index suggest that, all the regions specially the developing ∗ Corresponding author E-mail addresses: arfan@asia.com, thisisarfan@gmail.com (Md Arfanuzzaman), atiq.rahman@bcas.net (A Atiq Rahman) http://dx.doi.org/10.1016/j.gecco.2017.01.005 2351-9894/© 2017 Published by Elsevier B.V This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/ 4.0/) 10 Md Arfanuzzaman, A Atiq Rahman / Global Ecology and Conservation 10 (2017) 9–22 world have good room to improve the water condition in urban and household level for ensuring the long term well being of the nations, which can be done through properly implementing SWDM approach Broadly, sustainable WDM addresses how the countries are ensuring the efficient use of water to sustain their economic growth, food production, household consumption, industry, and energy (WWAP, 2015; ADB, 2013) The study focuses the case of Dhaka city of Bangladesh to investigate such problem and provide a systematic framework of sustainable water demand management for enabling social–ecological resilience, which may useful to the other countries with similar context Here, resilience refers to the capacity of a social–ecological system to absorb or withstand perturbations and other stressors such that the system remains within the same regime, essentially maintaining its structure and functions (Holling, 1973; Gunderson and Holling, 2002; Walker et al., 2004) Nevertheless to say, Dhaka is one of the highly populated mega cities in the world Unplanned urbanization, rapid industrialization and immense migration inflows are putting pressure to the principal public utility services system including electricity, energy, and water Further, policy lacks for the decentralization of Dhaka city is responsible to create deadlock for reducing population pressure from its frontier, which uplift the population size closely 16 million from the 3.03 million in 1980 In this backdrop, it is a challenging task to provide quality public utility services to the city dwellers Presently, 87% of the supplied water comes from the ground water resources and only 13% water comes from the surface water (SW) treatment plants to meet the growing demand of this huge population of Metropolitan Dhaka Dhaka is bordered by a good number of rivers such as Turag, Buriganga, Balu, and Lakhya, which are perilously polluted by the resident and commercial waste disposal, industrial effluent, and other anthropogenic activities (Islam et al., 2010a,b) The biological oxygen demand and the ecosystem of these rivers are no more exists at this moment (BBS, MICS and UNICEF, 2011) Besides, river filling, illegal housing are dangerously squeezing the river basin areas and swiftly eliminating the canal, ponds and wetlands from the Dhaka city (Biswas et al., 2010) In this backdrop DWASA is not getting sufficient source of fresh surface water, and facing technical and economic infeasibility to decontaminate the over polluted river water to the level of safe drinking water Thus, extreme stress falls in the ground water resources, which forces to deplete the ground water table comprehensively If the existing trend of ground water extraction continues the stock may no longer available in the future for withdrawal, which will make the society and ecology in irreversible condition (Uddin and Baten, 2011) Presently, the ground water level of Dhaka city dropped to more than 52 m below mean sea level (MSL) from the 34.18 m in 2000 and 26.6 in 1996 which is triggered by the excessive withdrawal and least ground water recharge As a result environmental degradation takes place around the city and the risk of intrusion of the southern saline water into the ground water reservoir is also appearing In this context, a sustainable water demand management (SWDM) policy becomes mandatory, which will incorporate the sustainable consumption, water extraction and distribution, optimum pricing, taxing for private deep wells, water conservation and water pollution Zahid and Ahmed (2009) strives to suggest an appropriate sustainability criterion in WDM for the fast urbanized mega cities around the globe, where water demand is relatively higher and increasing day by day along with depleting the ground water level In their words groundwater management must adopt an integrated approach taking into account a wide range of ecological, socio-economic and hydrological factors because country’s GDP is highly dependent on the development of water resources in general Uddin and Baten (2011) projected that if the existing trend of ground water extraction takes place, by 2050 groundwater level will go down 120 m in the Dhaka city and the present groundwater recharge of the city is counted only 1.33 m/y against 2.81 m/y of depletion rate Furthermore, the study has attempted to draw three scenarios considering existing water supply situation, future roadmap, unaccounted for water, downtime or production loss to project water demand and supply up to 2050 All of the three scenarios showed a large gap in water demand and supply situation The study suggests that, in order to meet the growing water demand effective and demand driven water supply management in essential for Dhaka city Change in tariff often use to change the water demand but water tariff alone does not influence the demand for water always Worthington and Hoffmann (2008) demonstrated that, price elasticity of water varied between −0.25 and −0.75 because water tariff represent a small proportion of income and has no substitute for basic uses Statzu and Strazzera (2009); and Schleich and Hillenbrand (2009) found that along with tariff and income level some other driving forces such as population characteristics, population density, immigration, household feature and economic growth are responsible to affect the water demand of urban areas Jamal and Rahman (2012) examined how the crisis of water and gas causing problem in the daily life of middle income locality of Dhaka and found local people are taking different adoptive measures, even compromising their daily life cycle to make and adjustment with these problems Kumar and Singh (2001) defined certain market based instrument for demand management in the face of water scarcity and over use of water in the agriculture of Western India The paper suggests the use of water market as the institutional arrangement for promoting economically efficient use along with rational pricing of canal water and electricity for encouraging conservation MAPC (2006) endeavors to produce a guideline for summer water demand management for Massachusetts and revealed that in many Massachusetts communities water consumption rises 50% or more during summer time, but water supplies are hampered as very city’s river is discharging very low water during summer months This mismatch between supply and demand is partly due to local water policies that tend to promise abundance and promote consumption The study recommends public education, voluntary conservation, conservation pricing, irrigation controls, and direct water use regulation are indispensable for the long term WDM along with compulsory investment, and political commitment Available studies are based on WDM and ground water depletion, but no paper has been found related to SWDM to conserve water resource and prevent ground water depletion from multidisciplinary perspective in the rapidly urbanized cities of the developing world In this backdrop, this study suggests a comprehensive approach and tools Md Arfanuzzaman, A Atiq Rahman / Global Ecology and Conservation 10 (2017) 9–22 11 Fig The boundary of Dhaka city and DWASA (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.) Source: Adopted from DWASA of optimum and SWDM for the mega city Dhaka and similar urban cities of the world as well to prosper the social–ecological resilience In addition, the scientific framework of this study will also help to improve the sustainability situation and enhance the understanding of cities water resource planning and management Materials and methodology The capital city of Bangladesh is considered as a study area Dhaka is placed in central Bangladesh at 23°42′ N 90°22′ E, on the eastern banks of the Buriganga River with an alleviation of m The city lies on the lower reaches of the Ganges Delta and has a population density of 23, 234/km2 (BBS, 2012) Dhaka experiences hot, wet, and humid tropical climate Under the Köppen climate classification, Dhaka has a tropical savanna climate and distinct monsoonal season, with an annual average temperature of 26.1 °C (79 °F) Approximately 87% of the annual average rainfall of 2123 mm (83.6 in.) occurs between May and October (Hough, 2004; Weatherbase, 2007) Besides, Dhaka is one of the twin hubs of the Bangladesh financial industry It has one of the largest concentrations of multinational companies in South Asia (Hossain, 2014) This study mainly covers the population of Dhaka which is under the coverage of Dhaka Water Supply and Sewerage Authority (DWASA) DWASA is a commercial water supply organization in the public sector which covers more than 360 sq km area with 15 million people (see Fig 1) 2.1 Data source The study is based mainly on secondary data collected from different sources and organizations Historical data of water demand, water supply, supply capacity, system loss, price level, deep tube well and population collected from Dhaka WASA 12 Md Arfanuzzaman, A Atiq Rahman / Global Ecology and Conservation 10 (2017) 9–22 Data of groundwater level and groundwater depletion have been collected from BADC Further, other required data and information are gathered from publications of Ministry of Water Resource, World Bank, Asian Development Bank and United Nations and scientific papers For the nature of this study both quantitative and qualitative research methods has been applied In order to make the analysis robust and scientific, statistical tools, GIS techniques, and data visualization method has been adopted throughout the paper 2.2 Quantitative techniques For better analyzing the time series data of different variables the significance of finding growth rate is high For the estimation of constant growth rate of Population, Water demand and Water supply following log linear model has been estimated LogY = β0 + β1 T + Ui (Gujarati and Porter, 2009) (1) where, Y is the depended variable, β0 denotes intercept, β1 indicates regression co-efficient, T represents time, and Ui is considered as a stochastic term Further, In order to assess the impact of different parameters such as population and price of water on the water demand semi log model has been used To squeeze the large values of population and water demand following semi log form regression model has been adopted ln Wd = β0 + β1 lnpopulation + β2 lnavgprice + Ui (Gujarati and Porter, 2009) (2) where, ln Wd is the log of water demand of Dhaka city, lnpopulation denotes the log of population, lnavgprice indicates the log of average price of water, and Ui is the stochastic term How much the explanatory variables are responsible to change the dependent variable can be examined by this model Per capita water consumption has been estimated based on the following equation Pwc = Tws Tp (3) where, Pwc indicates the per capita water consumption, Tws denotes the total volume of water supplied by Dhaka WASA, and Tp refers to the population of Dhaka city In addition, actual water supply of different years has been calculated by subtracting the amount of system loss of the particular year from the water supply capacity of Dhaka WASA Results and discussion Upward population growth and economic activities are crucial to increase household and industrial water demand in Dhaka city The Fig demonstrates the trend of water demand (both domestic and industrial) in Dhaka is increasing quite conspicuously since 1990s It is apparently noticed that in 1990 the demand for water was only 1000 million liters which is reached 1940 million liters in 2005 and 2240 million liters in 2012 During this period the population of Dhaka city was 5.56, 12.5 and 15 million correspondingly (DWASA, 1999) Rapidly growing population in this city remarkably causes the demand for water to increase Although, the water supply capacity of DWASA is also enlarged throughout the period the water deficit remain significantly higher It appears that, primarily shortage of water was 796 million liters Then it was further increased 2003 and 2004 After experiencing some volatility it goes down to 627 million liters in 2012 Increasing water supply capacity is not much effective to reduce the water shortage extensively against the growing demand for water due to system loss, old equipments, and management failure 3.1 Growth of population, water demand and supply in Dhaka city The estimates of log linear model, presented in Table illustrates that, growth of population, water demand and water supply is 5%, 4% and 6% respectively, which is statistically significant at 1% level Here, the growth of population is a bit higher than the growth of water demand Although, growth of water supply is higher than the growth of population and water demand it cannot meet the water demand due to existence of technical and managerial inefficiency of DWASA, and system loss The co-efficient of determination for all the models is more than 95%, which point toward the better goodness of fit of the models 3.2 Water tariff, consumption and groundwater level in Dhaka city The Fig illustrates that, per capita water consumption, supply capacity and price of water in Dhaka city is escalating per year It looks per capita water consumption was in steady state during the mid period and later on there is a uptrend Md Arfanuzzaman, A Atiq Rahman / Global Ecology and Conservation 10 (2017) 9–22 13 Fig Historical trend of water demand, supply capacity and deficit in Dhaka city Table Estimates of log linear model Source: Authors calculation based on the data of DWASA Co-efficient Constant t-statistics Std error Adj R2 Observation Population Water demand Supply capacity 0.05 1.91 14.8*** 0.003 0.94 17 0.04 7.06 15.26*** 0.002 0.92 17 0.06 6.53 16.11*** 0.004 0.93 17 Note: ∗ p < 0.10 ∗∗ p < 0.05 *** p < 0.01 in the per capita water consumption despite the increasing trend of water price in Dhaka city, which signifies price hike does not affect the water consumption of the city dwellers and industrial users Initially, per capita water consumption was estimated only 37 l per day, then it reached 80 l in 2005 and further soar to 108 l in 2012 and the rise in per capita water consumption can be assumed to be triggered by the increasing needs of household and economic activities, inefficient water consumption, and wastage Whereas, the per capita water shortage appears in downward trend which got pace after 2005 In 1990 per capita water shortfall was 143 l, which decline to 79 l in 2005 and further turn down to 42 l in 2012 Per capita water consumption increased and per capita water shortage decreased over the period due to augment the per capita supply capacity of water from 1990 to 2012 In initial period per capita supply capacity was 92 l, which arrive at 145 l in 2012 Average price of water (domestic and industrial) was found lower initially, which was increased BDT 17 (USD 0.22) at 2012 This increasing trend of per capita water consumption and declining trend of per capita water shortage indicates the excessive extraction of groundwater of the urbanized mega city Dhaka As 87% water supply is based on ground water resource of Dhaka city, rise in water consumption affects the ground water level to a larger extent (DWASA, 2014; Akther et al., 2009) In order to meet the extensive water demand of this rapidly growing city, a large number of deep tube wells were installed in different parts of Dhaka which are playing crucial role for groundwater depletion (Islam et al., 2010a,b) In 1990 there were only 216 deep tube wells in the city, which was 87 in 1980 To meet the increasing demand of water, installation of deep tube well took place rapidly since 2000 Right now the number of deep tube wells reaches to more than 610 to extract the ground water resources around the city, which are fueling the depletion of groundwater table It can be seen from Fig that, as the number of deep tube wells increased, the groundwater level is going down remarkably In 1997 groundwater level was 28 m from the mean sea level and in 2012 it crossed 70 m For the excessive withdrawal of water each year groundwater table is depleting on an average m in the capital city Dhaka (Khan, 2014; Nishat et al., 2008) 3.3 Sustainable water demand management approach In the present context of Dhaka city SWDM is essential to manage the water demand, reduce ground water depletion, and promote sustainable consumption for building social–ecological resilience In order to establish SWDM, sustainability is required to be attained in economic, social and environmental segment Here, a methodical list of indicators is developed 14 Md Arfanuzzaman, A Atiq Rahman / Global Ecology and Conservation 10 (2017) 9–22 Fig Trend of per capita water consumption, supply capacity and shortage Source: Authors estimation based on the data collected from DWASA Fig Trend of deep tube well installation and groundwater level for each section to attain the sustainability The overall framework of SWDM depends on the criterion of economic, social and environmental section 3.3.1 Economic sustainability in WDM Economic sustainability can be achieved by ensuring technical and allocative efficiency, water taxing, conservation pricing, sustainable consumption and production and reducing system loss The approaches and mechanisms are described as follows i Technical and allocative efficiency Technical efficiency refers to the maximum amount of output with minimum amount of inputs The water supply organization needs to be technically efficient to minimize the amount inputs Technical efficiency is related to the productive efficiency too If the water supply authority wants to achieve productive efficiency of water supply it must need to achieve technical efficiency Allocative efficiency requires the optimum allocation of resources Thus, in order to supply water at minimum cost and resources, and raise the revenue from water supply both technical and allocative efficiency are prerequisite The Fig 5a demonstrates that, technical efficiency occurs at point c where minimum inputs are required to produce the maximum amount of water Here, at y∗ , too much water is assigned to the low value Z activity, and ‘‘society’’ can gain from reallocating water from Z to Z If more water is allocated than y∗∗ to Z 2, any additional unit of water produces less revenue than allocating that unit to Z 1, and vice versa, thus the maximum efficiency occurs in y∗∗ Besides, Fig 5b indicates the allocative efficiency of water supply Here, in production function, point a, b and c designates the quantity of water that can be produced by the different allocation of resources Here, point c is the maximum amount of water that can be produced Md Arfanuzzaman, A Atiq Rahman / Global Ecology and Conservation 10 (2017) 9–22 15 Fig 5a Technical efficiency c>a>b production Production fn c b a Water Fig 5b Allocative efficiency by utilizing the given amount of resources Hence, in order to achieve economic sustainability DWASA need to assure both technical and allocative efficiency ii Demand management and optimum pricing In order to administer the demand of water in a sustainable way, drivers of demand require to be managed effectively The trouble faced by the toady’s water sector is that prices and tariffs are almost universally below the actual cost of supply This indicates that almost everywhere there are large inefficiencies in the water sector and that water tariffs are required to be increased It appears in Table that, both population size and tariff of water has positive influence on the demand of water in the Dhaka city The estimate suggests one percent change in population of Dhaka city lead to change the water demand by an average 0.68% So, increased population is a dominant factor to increase the demand for water in the city Besides, there is a positive relationship found in the estimates between the water demand and water tariff Since, the price of water is lower in Dhaka city compared to other utility services, people tend to consume much water It requires long term and effective govt policy to reduce population pressure from Dhaka but in case of effective water demand management (WDM) there is no alternative for optimum pricing from the perspective of water conservation For industrial and domestic users the approach and principle of pricing should be different Optimum water pricing is also mandatory for economic sustainability of WDM If water is available at cheaper rate people tend to consume more water and the chance of wastage and overuse of water will be increased It emerges in Fig that, when price of water was lower consumption was at Y2 when higher price charged water consumption declined to Y1 As per capita water consumption trend and Table signifies present pricing structure is not enough to affect the demand, adequate room is there to adjust the existing water tariff with a view to make the water demand effective and sustainable Only, optimum water pricing can ensure the sustainable consumption, production and conservation of water In optimum water pricing water should be considered as an economic good also Since, people of all social categories have equal right to access and avail water, the price for required minimum amount of water to lead the daily life should be kept lowest Since, the price of water and income level is the determining factor of water demand, pricing rule is used often to manage the water demand around the globe Some previous studies presented in Table illustrates that, there is 16 Md Arfanuzzaman, A Atiq Rahman / Global Ecology and Conservation 10 (2017) 9–22 Table Estimates of robust multiple regression model Source: Authors calculation based on the data of DWASA Coefficient Std error t statistic Constant R squared Observation Population Tariff of water 0.68 0.088 7.78*** 0.13 0.091 1.49* 5.46 0.98 17 Note: * p < 0.10 ∗∗ p < 0.05 *** p < 0.01 Table Impact of price and income on water demand in different countries Authors Country Price Income García-Valiđas (2005) Statzu and Strazzera (2009) Martins and Fortunato (2007) Schleich and Hillenbrand (2009) Nauges and Thomas (2000) Bithas and Stoforos (2006) Bartczak et al (2009) Höglund (1999) Molle (2007) Dudu and Sinqobile (2008) Spain Italy Portugal Germany France Greece Poland Sweden India Srilanka − − − − − − − − − = + + = + + + + = = + +, − and = indicates positive, negative and no impact on water demand respectively Supply of Water E P1 P2 Demand for Water Y1 Y2 Quantity of Water Fig Optimum pricing rule of water an adverse relationship between price of water and demand, and positive relationship between income and demand This indicates price regulation can control of demand for water even though the income level is higher The Fig illustrates that, water tariff in Dhaka city is much lower compared to other mega cities of Asia In India, Singapore, Kathmandu, Jakarta, Manila, Kuala Lumpur and Dhaka tariff of per thousand liter of water is USD 2.27, 1.22, 1.06, 0.7, 0.6, 0.45 and 0.22 correspondingly Since, water demand is relatively higher in Dhaka city and tariff is still very low compared to other Asian cities, enough room is there to introduce demand sensitive and conservation pricing rule for the rapidly growing population of the city In order to maintain the welfare of the people with different income level different kind of pricing strategy such as quota pricing, peak, of-peak pricing, increasing block rate, cost recovery pricing can be adopted rather than any ad hoc pricing Since, Dhaka WASA follows ad-hoc pricing rule rather than appropriate price regulation; there is a good space for demand management through a strategic and sustainable pricing mechanism for different user groups such as household, marginal community (slum), industry etc (Huq, 2014; Pardy, 2012; Solanes and Jouravlev, 2006) iii Reduce system loss System loss is one of the key barriers for unremitting and optimal water supply in different cities around the world (Takizawa, 2008) Higher system loss make the entire WDM system economically inefficient and questionable as well Thus, Md Arfanuzzaman, A Atiq Rahman / Global Ecology and Conservation 10 (2017) 9–22 17 Fig Water tariff in different Asian cities Source: Delhi Jal Board (2015), Kathmandu Post (2014), Public Utilities Board (2012) for Singapore, FDC (2009) for Manila, Berg and Danilenko (2011) for Kuala Lumpur, Syaukat (2009) for Jakarta Fig Trend of system loss of Dhaka WASA trimming down the system loss up to the mark is another prerequisite of economic sustainability It is appeared in Fig that, In 1990 the overall system loss of Dhaka WASA was recorded 60% which was came down to 40% in 2004 and reached 41% in 2008 through gradual ups and down Despite all the variation the overall system loss reduce to 26% in 2012 It is a first-rate achievement of DWASA that it reduces system loss to 26% from 40% within last four years Better management, operational strategy and regulation plays a commendable role to ultimately ease the system loss from the superior level The initial reduction of system loss is less costly compared to the next stage Up to certain level of system loss can be reduced by increasing public awareness and enhanced monitoring and regulation If DWASA want to reduce system loss further, old mercenaries, equipments and pipelines are required to be replaced, which needs more investment and it will produce higher economies of scale in the long run 3.3.2 Social sustainability in WDM It is a challenging task to maintain social sustainability in WDM in the highly populated cities, but better regulation and strategy can ensure the social sustainability If social sustainability is achieved in SWDM the welfare of the citizen will be increased In order to attain social sustainability, equity and water for all are essential to be made certain i Equity in WDM Equity is a vital element in the social sustainability of WDM Without it SWDM cannot be achieved in the society Generally, acute equity problem occurs when poorest groups pay more per unit of water than other social groups Acute equity accelerated when partial coverage of potable water available in the urban areas There is an enough room to work on the equity issue of water consumption in Dhaka city Lowest income group such as people of urban slums and other poor 18 Md Arfanuzzaman, A Atiq Rahman / Global Ecology and Conservation 10 (2017) 9–22 communities is not fully covered by Dhaka WASA and rich and poor people pay the similar price for water Thus, in order to achieve social sustainability emphasize must be given on equity by the water supplier authority and government as well ii Water for all Inadequate water access for drinking or for other purposes by certain groups of large numbers of people and in certain parts of the country is becoming increasingly serious Bangladesh needs stricter enforcement of the policies and water related laws and more effective endeavors from both government and non-government actors in realizing the goal of ensuring accessibility to quality water for all citizens which will ensure social sustainability of WDM as well Otherwise water crisis and water born diseases will be spread among the poor people Rich people have the capability to install the equipment to withdraw ground water for consumption but poor people cannot afford it and bound to go for unhealthy water source So, the water supplied by the Dhaka WASA should be safe for drinking and delivered to all In this context, Dhaka WASA can introduce water rationing for the poor and marginal communities, increase the pipeline coverage for the slums and offer fresh water at a subsidized tariff to the poor In Bangladesh the average annual per capita availability of water is nearly 7500 cubic meters, around five times higher than that in India (FAO, 2014) Highly uneven seasonal and spatial distribution of available water in Bangladesh poses severe problems Dhaka WASA can utilize the surplus water resources of monsoon and rivers water to increase its water supply capacity Along with safe drinking water it is also need to ensure that the people gets the minimum required water to lead their daily life, which is also a prerequisite for SWDM 3.3.3 Environmental sustainability in WDM In environmental sustainability of WDM water production, distribution and consumption must produce positive environmental effects Otherwise environmental sustainability will be intangible In order to attain environmental sustainability in WDM indicators related to the environment of Dhaka city need to be satisfied The criteria of environmental sustainability of WDM are discussed as follows i Reduce groundwater depletion and pollution Ground water groundwater depletion is one of the major problems of Dhaka city, which is growing each year and putting severe risk to the ecology In 1997 the groundwater level of Dhaka was 28.15 m below which further went down to 42 m in 2002 Ultimately, in 2012 groundwater depletes more than 70 m from 61.8 m in 2007 The present condition does not allow extracting water from the city’s ground If water table continues to fall then a vacuum will be created in the aquifer which could cause a sudden collapse in the surface (Rahman and Hossain, 2008) In this circumstance, to protect the soil layer from massive collapse and manage groundwater resource, reliance should be transfer significantly from groundwater to surface water (Siddique et al., 2000; Islam et al., 2010a,b) Fig points up that, the central part of capital city Dhaka is in relatively critical environmental zone as groundwater level is went down up to 70 m and a considerable part of surrounding areas are also in the risk of critical zone The zones in between the range of 41–75 are in the risk of extreme environmental degradation and future water scarce zone due to rapid groundwater exhaustion and these areas should be declared as an ecologically critical areas and conservation policy must be taken regarding this concern Thus, in order to satisfy the criterion of environmental sustainability groundwater depletion must reduce right away from the risky areas of Dhaka city though optimum hydrological planning and management including reducing groundwater extraction rate, ensuring maximum groundwater recharge, surface water management, groundwater conservation and promote rainwater harvesting A good number of rivers such as Turag, Balu, Sitalakhya, Buriganga and Dhaleswari are surrounding the Dhaka city which is now highly contaminated for the disposal of waste, sewage, manufacturing effluent, and household pollutant matters Over 300 outfalls of domestic waste water, sewerage wastes, and industrial effluent are polluting the rivers every day and diminishing the stock of surface water resource of the Dhaka city (Paul, 2009; Islam et al., 2010a,b; WB, 2007) Hence, water pollution need to be controlled to maintain the sustainability as well as protect the precious water bodies and wetlands 3.4 Instruments for achieving sustainable water demand management i Efficiency in water consumption In order to achieve SWDM, sustainable consumption is also necessary to promote Water consumption directs water pollution and high volume of water extraction and consumption lead to reduce the reserve of groundwater level Thus, Environmental sustainability is also cannot be achieved without attaining sustainable consumption Condenses pollution form water consumption and reduced water footprint can foster the concept of sustainable water consumption in the rapidly urbanized Dhaka city as well as other mega cities of the world Here, promoting water efficient device such as rain gauges, leak detection kit for toilets, bathroom flip aerators, dual setting flip aerator with swivel for the kitchen, low-flow showerheads, shower timers, recycling technology, and improved water productivity can significantly reduce the household and industrial water footprint Furthermore, public information campaign, water education in school which includes field trips, drinking water related lessons and activities, consultation on integrating drinking water topics, prepare educational videos, books, and other resources on water saving and efficient water use will help to reduce water footprint Besides, rebates for replacement of inefficient toilets, shower and other household and industrial equipments, quarterly E-water newsletter by DWASA containing different information and message, online information, alert high water user for their Md Arfanuzzaman, A Atiq Rahman / Global Ecology and Conservation 10 (2017) 9–22 19 Fig Ground water depletion in Dhaka in 2010 (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.) usages can inspire people to go for water smart device and technology as well as adopt sustainable consumption pattern in the city life However, promoting water-wise garden it also can be good idea in the Dhaka city The water garden includes drought-resistant plants, organic mulches, and water-wise design principles, which will create interest to the urban people to make their living environment green with less water foot print Besides, sustainable water consumption will also play a considerable role for the water conservation ii Promoting optimum water demand SWDM seeks to influence water demand to reach the consumption levels that are equitable, efficient and sustainable The chief motto of sustainable water consumption (SWC) is to reduce water foot print and pollution from consumption Pollution can be reduced by public outreach program but what about water conservation? Water conservation is also possible to attain by adopting the optimum water consumption pattern which is sustainable off course in terms quantity According to WHO, minimum of 50 l per capita and day (LPCD) is required to fulfill the needs for consumption and hygiene (Gleick and Iwra, 1996) Here, l per day (LPD) are required for drinking water, 10 LPD for food preparation, and 35 LPD for bathing and sanitation services For the highly populated cities 50 LPD is sustainable and also sufficient to ensure optimum water consumption This will be also helpful for reducing water foot print, ensure conservation and manage water demand in the urban areas of the world Fig 10 signifies the scenario of anticipated water demand in case of sustainable consumption Here, 50 LPCD is considered as a SWC level according to WHO minimum requirement It emerges that if 50 LPCD can be consumed the water demand reduces by more than 60% and if 100 LPCD can be consumed the water demand trim down by 40% in Dhaka city It can be observed that the water consumption is higher since the begging period If SWC can be adopted earlier the water demand may not reach at this peak position In the present condition if water foot print can be reduced by promoting the sustainable consumption groundwater depletion can be reduced significantly Initially it may be challenging to achieve 50 LPCD but it can be started from 100 LPCD then gradually it can be turned to 70 and then 50 LPCD Since, our per capita water consumption is increasing per year enough span is there to trim down the per capita water consumption by promoting SWC In this way SWDM can be achieved easily by promoting SWC which is 50 LPCD Simultaneously, it is also need to be keep in mind that 50 LPD water is available to all iii 100% metering Full metering of water users is one of the most basic steps in a water conservation program at which different water unit prices apply in an ascending rate structure Alternatively, customers can be given a discount for meeting the goal, or charged a penalty for exceeding it (as with wasteful use rates) The discount/penalty system can be used with any rate structure, including a flat unit rate structure or even a flat fee structure, to make the cost of water more tuned to conservation 20 Md Arfanuzzaman, A Atiq Rahman / Global Ecology and Conservation 10 (2017) 9–22 Fig 10 Water demand of Dhaka in case of sustainable consumption Source: Authors’ calculation based on the data of DWASA Cost of extraction Cost with externality Private cost With extraction tax No tax demand quantity Fig 11 Impact of tax on groundwater extraction goals In Dhaka 75% connections are metered Hence, to make the metered connections rate 100% Dhaka WASA need to work effectively on it iv Tax on private water withdrawal For the sustainable water conservation ground water resource must be managed and extracted in a planned way Along with DWASA lots of private users and households withdraw limitless ground water which imposes adverse effect on ground water depletion of Dhaka city This is happened due to inability of DWASA to meet the water demand of city dwellers 24/7 Besides, some area of Dhaka city those who are not covered by DWASA or does not have any water connection from DWASA also depends on their own ground water withdrawal system There is no any updated and exact statistics on how much residents and firms withdraw how much ground water by their own equipment In this case it is requisite to prepare area wise list of these residents and firms to manage water conservation program by a sustainable regulation Water conservation can be managed by imposing tax on excessive private water withdrawal, quota pricing, volume based pricing or metering Without any tax or fee it is not possible to successfully administer the water conservation program in a sustainable manner The Fig 11 demonstrates when there is no tax, water extraction increases significantly by the residents or firms and vice versa in case of taxation So, by imposing tax or additional fee private water withdrawal can be reduced considerably and the people will tend to use water efficiently Only imposing tax will not be an optimum solution unless some alternative mechanism is developed For example, govt can take effective measures to promote the rainwater harvesting system in the city areas and provide basic incentive on it It deserve special mention that, above 15% of the total water supply can be met by harvesting rainwater in Dhaka city as the city has around 370 km2 of land with a roof area of 75 km2 consists of more than 675,000 concrete houses (Islam et al., 2010a,b) Consequently, water conservation will also be ensured in such way Md Arfanuzzaman, A Atiq Rahman / Global Ecology and Conservation 10 (2017) 9–22 21 Conclusion and recommendation In the present context, the ground water depletion, industrial and household water footprint need to be reduced for the best possible water management of the Dhaka city Sustainable water demand management (SWDM) can be an optimum choice for conserving and managing water resources SWDM is integrated approach and its criteria are feasible to attain for the mega cities including Dhaka through proper planning, management and investment Integrated policy, co-operation among the utility services provider and public reinforcement can help to adopt the SWDM quickly Water efficient device and technology may be costly In this case incentive should be provided to the local firm to produce this type of devices and import of water smart technology can be made duty free Implementation of water smart device and technology can be made mandatory for the high volume user and the commercial sectors Besides, surface water resource should be developed as a reliable source of water supply along with the groundwater resource Because a remarkable part of Dhaka city under severe risk due to massive groundwater depletion In addition the sources of SW such as water bodies and rivers need to be protected by ensuring better waste management and ETP for the industries Moreover, endeavor should be made on sustainable water consumption The ultimate SWC target is 50 LPCD but initial goal can be 100 LPCD against the existing demand per capita SWC can considerably trim down the water foot print as well as water demand of the Dhaka city Govt can promote rain water harvesting with incentive system specially in the critical areas to conserve the water resource Rooftop rainwater harvesting systems are already compulsory for the newly constructed buildings in the 18 states of neighboring country India The Karnataka state government of India has proposed giving a 5%–10% cut on water bills for users that install water harvesting systems In 2010, Delhi government was also directed all its departments, local bodies and public sector organizations to install rainwater harvesting systems in their buildings Although, Bangladesh’s capital development authority, Rajdhani Unnayan Kartripakkha (RAJUK), made rainwater harvesting for new houses mandatory in an effort to address water scarcity and reduce flooding, is note seen very ineffective Similar rain water harvesting model can be followed in Dhaka city to reduce the pressure from groundwater resource Since, a huge number of city dweller and commercial farms involve on limitless groundwater extraction, tax should be imposed shortly to restrict limitless the private water withdrawal This will help to reduce groundwater depletion and also reduce the needless water consumption Water mining should be discontinued by DWASA from the red zones of Dhaka city, where groundwater level goes down more than 50 m from the MSL until groundwater recharge take place in these areas up to the standard level Or else, sudden collapse of soil layer may emerge in these ecologically critical red zones The rapidly urbanized and highly populated cities, where water demand is high, SWDM is an optimum option for them, which deserve immediate deliberation on the policy making process According to the Far Eastern Economic Review, a good number of mega Asian cities such as Dhaka will be home to 25 million, Jakarta 24.9 million, Karachi 26.5 million, Shanghai 27 million and Mumbai 33 million people by the end of 2025 If we cannot establish a SWDM approach from now on the water management will be a very difficult task for the growing population in the years to come To implement SWDM a reform in the existing structure, perspective water and environmental planning and management, and healthy investment are required Here, a noticeable part of investment can be generated through executing pollution tax and payment for ecosystem services Besides, proper budget allocation, capacity building, intuitional efficiency, good water governance, public awareness and enforcing environmental law and policies are highly essential to initiate and well execute the overall approach of SWDM and attain the social–ecological resilience Otherwise, SWDM may not run properly and efficiently Acknowledgments The authors are thankful to Dhaka WASA for providing necessary data and information to carry out the study Authors are also grateful to Prof Dr ATM Zahural Huq, former chair of Dhaka WASA for proving ideas and inspiration to prepare this paper The writers are indebted to many of our colleagues for discussions and ideas that are reflected throughout this paper We are also indebted to the journal’s editor, and anonymous referees for critical and helpful comments that have much improved the paper References Akther, H., Ahmed, M.S., Rasheed, K.B.S., 2009 Spatial and temporal analysis of groundwater level fluctuation in Dhaka city, Bangladesh J Asian Earth Sci (2), 49–57 Asian Development Bank (ADB) 2013 Asian Water Development Outlook 2013: Measuring water security in Asia and the Pacific Mandaluyong City, Philippines Bangladesh Bureau of Statistics (BBS) 2012 Statistical year book, GoB Bartczak, A., Kopanska, A., Raczka, J., 2009 Residential water demand in a transition economy: evidence from Poland Water Sci Technol.: Water Supply (5), 509–516 BBS, MICS and UNICEF, 2011, Bangladesh National Drinking Water Quality Survey of 2009, Bangladesh, Online available at: http://www.unicef.org/bangladesh/BNDWQS_2009_web.pdf Biswas, S.K., Mahtab, S.B., Rahman, M.M., 2010 Integrated water resources management options for Dhaka City In: Proc of International Conference on Environmental Aspects of Bangladesh, ICEAB10, Japan Bithas, K., Stoforos, C., 2006 Estimating urban residential water demand determinants and forecasting water demand for Athens Metropolitan Area, 2000–2010 South-East Eur J Econ 1, 47–59 Dudu, H., Sinqobile, C., 2008 Economics of irrigation water management: A literature survey with focus on partial and general equilibrium models Policy Research Working Paper 4556 The World Bank 22 Md Arfanuzzaman, A Atiq Rahman / Global Ecology and Conservation 10 (2017) 9–22 DWASA 1999 Dhaka Water Resources Management Program Briefing, Vol 2, Issue 2, February, Karwan Bazar, Dhaka DWASA 2014 Annual Report Karwan Bazar, Dhaka Food and Agriculture Organization (FAO) 2014 AQUASTAT, FAO’s global information system on water and agriculture http://www.fao.org/nr/aquastat García-Valiđas, M.A., 2005 Efficiency and equity in natural resources pricing: A proposal for urban water distribution service Environ Resour Econ 32, 183–204 Gleick, H.P., Iwra, M., 1996 Basic water requirements for human activities: Meeting basic need J Water Int 21 (2) Gujarati, D.N., Porter, D.C., 2009 Basic Econometrics McGraw-Hill Irwin, Boston Gunderson, L.H., Holling, C.S (Eds.), 2002 Panarchy: Understanding Transformations in Systems of Humans and Nature Island Press, Washington DC Höglund, L., 1999 Household demand for water in Sweden with implications of a potential tax on water use Water Resour Res 35, 3853–3863 Holling, C.S., 1973 Resilience and stability of ecological systems Annu Rev Ecol Syst 4, 1–23 Hossain, A., 2014 Branding Bangladesh: India’s Neighbor is Becoming a Major Startup Hub huffingtonpost, http://www.huffingtonpost.com/anushayhossain/branding-bangladesh-india_b_4671353.html (accessed on May 2016) Hough, Michael, 2004 Cities and Natural Process Routledge, ISBN: 0-415-29855-5, pp 64–65 Huq, ATM Zahuru, 2014 Appropiate pricing rule for public utilities: review of pricing policy followed by Dhaka WASA Vol 1, Issue 1, pp 1–11 Islam, M.M., Chou, F.N.F., Kabir, M.R., 2010a Feasibility and accesibility study of rainwater use to acute water shortage areas in dhaka city Nat Hazards 11, Springer Islam, M.S., Rahman, M.R., Shahbuddin, A.K.M., Ahmed, R., 2010b Changes in wetland in dhaka city: Trends and physico-environmental consequences J Life Earth Sci 5, 37–42 University of Rajshahi Jamal, Shila, Rahman, Sonia., 2012 Adopted community strategies to offset utility crises in a middle income locality of Dhaka, Bangladesh Dev Country Stud (9) Khan, A.Taqsem, 2014 The Daily Star, Interview Published at March 22 Kumar, M.Dinesh, Singh, O.P., 2001 Market instrument for demand management in the face of water scarcity and overuse of water in Gujrat, Western India Water Policy 3, 387–403 Martins, R., Fortunato, A., 2007 Residential water demand under block rates-a Portuguese case study Water Policy 9, 217–230 Metropolitan Area Planning Council (MAPC) 2006 SummerSmart Water Use 60 temple Place, Boston Molle, F., (nd) 2007 Water Scarcity, Prices and Quotas: A Review of Evidence on Irrigation Volumetric Pricing Institute de Recherche pour le Development, 911, Avenue Agropolis BP 64501, 34394 Montpellier Cedex 5, France Nauges, C., Thomas, A., 2000 Privately-operated water utilities municipal price negotiation, and estimation of residential water demand: The case of France Land Econ 76, 68–85 Nishat, B., Rahman, S.M.M., Kamal, M.M., 2008 Environmental assessment of the surface water sources of Dhaka City In: Proc of International Conference on Sustainable Urban Environmental Practices, pp 19–30, Southeast Asia Urban Environment Applications (SEA-UEMA), Chiang Mai, Thiland Organization For Economic Co-Operation and Development (OECd) 2012 Environmental Outlook to 2050: The Consequences of Inaction Paris, http://dx.doi.org/10.1787/9789264122246-en Pardy, B., 2012 False panacea: The human right to water In: Bigas, H (Ed.), 2012, The Global Water Crisis: Addressing an Urgent Security Issue Papers for the InterAction Council, 2011-2012 UNU-INWEH, Hamilton, Canada, pp 136–141 Paul, Reba, 2009 Water security in Dhaka city: an initiative of Government of Bangladesh In: Paper Presented at 6th Governing Council Meeting of Asia Pacific Water Forum November 30, Singapore Rahman, S., Hossain, F., 2008 Spatial assesment of water quality in peripheral rivers of dhaka city for optimal relocation of water intake point Water Resour Manag 22, Schleich, J., Hillenbrand, T., 2009 Determinants of residential water demand in Germany Ecol Econom 68, 1756–1769 Siddique, K., Ahamed, J., Ahamed, M., 2000 Overcoming Governance Crisis in Dhaka City The University Press limited, Dhaka Solanes, M., Jouravlev, A., 2006 Water Governance for Development and Sustainability Natural resources and Infrastructure Series No 111 Santiago, Chile: Economic Commission for Latin America and the Caribbean (ECLAC) Available at: http://www.eclac.org/publicaciones/xml/0/26200/lcl2556e.pdf Statzu, V., Strazzera, E., 2009 Water demand for residential uses in a mediterranean region: Econometric analysis and policy implications Available online: http://www.cide.info/conf/2009/iceee2009_submission_88.pdf (accessed on 20.06.14) Takizawa, S., 2008 Ground Water Management in Asian Cities: Technology and Policy for Sustainability Springer, Japan Uddin, A.F.M.A., Baten, M.A., 2011 Water Supply of Dhaka City: Murky Future Unnayan Onneshan Dhaka, Bangladesh UNDESA (United Nations Department of Economic and Social Affairs) 2012 Back to our Common Future: Sustainable Development in the 21st Century (SD21) project new York, United Nations (UN) Walker, B., Holling, C.S., Carpenter, S.R., Kinzig, A., 2004 Adaptability and transformability in social-ecological systems Ecol Soc 9, Weatherbase 2007 Monthly weather averages summary Available online: http://www.weatherbase.com/weather/weather.php3?s=32914&cityname= Dhaka-Dhaka-Bangladesh&units=metric (accessed on 21.06.14) World Bank, 2007 Dhaka: Improving Living Conditions for the Urban Poor Dhaka, The World Bank Office Worthington, A.C., Hoffmann, M., 2008 An empirical survey of residential water demand modeling J Econ Surv 22, 842–871 WWAP (United Nations World Water Assessment Programme) 2015 The United Nations World Water Development Report 2015: Water for a Sustainable World Paris, UNESCO Zahid, Ahmed, 2009 Groundwater Resources Development in Bangladesh: Contribution to Irrigation for Food Security and Constraints to Sustainability Ground Water Hydrology Division, Bangladesh Water Development Board, Dhaka ... ii Demand management and optimum pricing In order to administer the demand of water in a sustainable way, drivers of demand require to be managed effectively The trouble faced by the toady’s water. .. of the southern saline water into the ground water reservoir is also appearing In this context, a sustainable water demand management (SWDM) policy becomes mandatory, which will incorporate the. .. to maintain the sustainability as well as protect the precious water bodies and wetlands 3.4 Instruments for achieving sustainable water demand management i Efficiency in water consumption In order