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Sustainability actions are designed to reconcile two competing forces: environmental considerations and the rising demands of the ever-increasing population, when the resources are finite. The resources comprise natural endowments, which define the broader limits up to which they can sustain the population and its demands, and social and technological advancements, which define how efficiently – or inefficiently – the resources are used. The sustainability agenda is pursued by trying to achieve a balance between (a) the development agenda and (b) the societal goals and associated ‘transformations’ in physical, institutional, and governance structures. The social-economic-ecological metabolism helps in understanding how human and economic development depends on, and interacts with, the natural environment.
The present research seeks to apply the social-ecological metabolism approach to urban water planning to investigate the nexus between social and environmental objectives of urban planning by showing cities as tightly coupled social-ecological systems, using Delhi as a case study. The central objectives of the study are (a) to understand the patterns of water consumption in the domestic sector and its variation as influenced by the socio-economic and demographic status of households and to ascertain the ‘real’ water demand; (b) to identify strategies used by urban residents to deal with the deficiencies in water supply and to assess the impact of the use of modern water-related appliances on the consumption of water and electricity; (c) to account for water inflows and outflows (including wastewater) and to construct a well-defined water mass balance to assess the extent to which a city’s water supply is sustainable; and (d) to demonstrate the diversity of drivers and the trade-offs between water and other sustainability goals as seen in the water–energy nexus. The study attempts to illustrate the benefits of using a system approach to urban planning instead of the conventional sectoral planning approach. Water and energy are two critical urban infrastructure services and it is important that the policies related to these services and other associated policies take into account the close interaction between these the water sector and the energy sector.
The study is also important given the fact that water demand is influenced by many intersecting cultural, climatic, demographic, infrastructural, social, and physiological factors (Fan et al. 2014; Willis et al. 2013). The greater penetration and use of modern appliances in urban households influence the consumption of water (which is typically lowered) and of electricity (which is typically increased) (Schuetze and Santiago-Fandiño 2013). However, urban planners assess a city’s water demand through only one simple statistic, namely the recommended or normative per-capita water supply: a figure that has not been revised for decades, does not appear to reflect social equity, is not supported by any explicitly stated rationale—and is widely variable. There is little evidence that these norms are based on any real demand assessment.
Historically, Delhi’s urban growth has been horizontal, starting from the walled city during the pre-colonial period and expanding in concentric circles, engulfing the smaller surrounding villages, and merging with New Delhi. Geographically, Delhi is also a conurbation and its satellite towns, which are under different political administrations, share the region’s natural resources with Delhi. Delhi’s is a story of anthropogenic alteration and its impact on hydrology: the city has become a water-deficit region; small streams and lakes have disappeared; traditional water structures have been dismantled; the Yamuna, after crossing the city’s boundary, runs dry for nearly 8 months a year; 43% of Delhi’s centralized water supply comes from a source a few hundred kilometres away; and groundwater development is 137%, which is critical and significantly constrained for access to water resources. The techniques and institutions related to water supply have changed from a distinct decentralized, community-driven, and state-patronized system to a completely state-managed system for supplying water to the public. The present debate about water management is on the following question: Can Delhi be made water sensitive when water is reduced to a mere commodity that money can buy?
This debate is to be seen in the light of many other suppositions including the following: 1) water is a finite natural resource without substitutes; 2) horizontal urban growth pushes human settlements away from natural water sources; 3) water demand of an urban area, in most cases, outstrips its natural endowment; and 4) high population density and economic restructuring have tendency to alter the character of water from ‘blue’ to ‘grey’, endangering the environment.
However, to make Delhi a water-sensitive city, the first step is to make it water independent, which requires some understanding of its hydrology and water mass balance. Through a primary survey, we examined the pattern of water consumption in the domestic sector in Delhi. More specifically, the study sought answers to the following questions: (1) How does per-capita consumption of water at home vary with the socio-economic and demographic status of the household? (2) How do the strategies that people use to cope with inadequate and erratic supply of water of questionable quality influence the total household consumption of water and of electricity? (3) How does the demand for water change with the use of modern water-related appliances? The study also examined the water–energy nexus related to water infrastructure at the level of urban households.
Changing lifestyles and greater use of technology by urban households have impacted the consumption of both water and electricity. The dominance of the tertiary sector in the economy and the global economic downturn have led to urban adults working longer hours away from home, thereby shifting their demand for water from the domestic sector to the institutional and commercial sectors. The number of households switching to electrical appliances such as dishwashers and washing machines to save time continues to rise: although this trend reduces water consumption, it increases electricity consumption at the same time. Thus, water-saving measures are negatively correlated to electricity consumption at the level of end users. Inadequate quantity and unreliable quality of water increase the demand for water as well as electricity in the domestic sector, and those – for example, slum dwellers – who cannot afford the additional expense required to cope with these shortcomings in water supply end up paying for them at the cost of health, sanitation, and hygiene.
The study found that within organized housing, water consumption did not differ significantly with income. The basic water requirements of a resident in Delhi were 76–78.3 lpcd (liters per capita per day). Bathing claimed a major share of household water consumption, although the majority used a bucket and a mug for bathing, which requires less water than that for a shower or a bath tub; this practice, together with the fact that most do not have private gardens, makes per capita water consumption in Delhi lower than that reported in the literature for many developed countries.
Electricity consumed by households on water-related activities amounted to about 15 kWh a month. Of this electricity, approximately 11 kWh (70%) is used only to make up for the deficiencies in water supply. Domestic water consumption in Delhi is likely to stabilize at approximately 71 lpcd as the use of such appliances as dishwashers and washing machines (which use water more efficiently) increases and the quality of water supply by the Delhi Jal Board (DJB, which is Delhi’s water utility) improves; however, these improvements also mean greater electricity consumption. Thus, there is the hidden cost of coping with deficiencies in water supply, although most households do not realize this. This analysis strengthens the case for rationalizing water tariffs with commensurate improvements in service by urban water utilities and for making a realistic assessment of the current water supply norms.
Considering the water mass balance, the total annual water inflow in Delhi (including water imported under the existing interstate agreements) is 2095 MCM (million cubic meters) whereas the discharge is 1621 MCM. Nearly half the water flowing through the system remains unused and rest is used only once, except the water used by thermal power plants, agriculture, and public facilities such as parks.
The research assessed the annual ‘real urban water demand’ at 694.7 MCM, or 119 lpcd, with water losses considered as 15% as against the current reported figure of 30%–40%. The normative value of 270 lpcd used by the DJB is therefore excessive in today’s context and leads to inefficient use of water, which makes up for the high proportion of losses (30%–40%) due to old and dilapidated water distribution infrastructure.
The water-use intensity of Delhi is high, and the share of centralized supply in the total water supply is only 67%, which points to the existence of a private water market and lack of regulatory control over private groundwater abstraction. Although rainfall can meet only 65.3% of Delhi’s current water needs, due to the lack of rainwater-harvesting and storage facilities in the city, the city is not able to meet even this need. The growing demand for water is supplemented by water obtained from sources far away, which contributes only 67% of the centralized supply. This reflects a linear approach to water resource augmentation from outside the city limits, making Delhi a water-insecure city.
Delhi has the potential to supply water to other regions in the short term and to be a water sustainable city in the medium term to long term by diversifying its water sources and using water more efficiently. But lack of rain water storage structure limits the city to meet even this need. The alternative sources are recycled wastewater (use replaceability is 78.2%), and rainwater (use replaceability is 65.3%), however, the city is even not able to utilize the recoverable potential available. Besides, water losses need to be curbed and the demand needs to be assessed periodically in more realistic terms to add to the water security of Delhi, making it water sustainable city.
The cost of creating structures for recycling wastewater and for tapping storm water is broadly estimated at $490 million, and a similar amount of investment is needed to build rainwater storage structures and to retrofit the existing infrastructure to reduce water losses. Therefore, with an investment of about $1 billion, supplemented with participation of more players in the water supply sector and with adequate institutional and governance mechanisms and adaptive and flexible planning, Delhi can be a water-surplus city. The local government may argue that investments on such a large scale are not possible given the limited financial resources. However, Delhi’s urban water sector reforms can be the model of a transition to a civilization that lives within its own means.
The public water supply system in Delhi consumes energy equivalent to 5721.4 MWh a day, of which 66% is in the form of electricity and 5% is in the form of diesel (consumed mostly by water tankers); 97.6% of that energy is used for operating the water infrastructure (operational phase). Inadequate water infrastructure and unreliable supply increase energy consumption. Water tankers meet only 1% of the total water requirements of the city but consume as much energy as that consumed by the pipeline infrastructure—which meets 99% of the water requirements. Similarly, consumers end up using 1500 MWh of electricity annually to cope with inadequate water supply of unreliable quality.
The water–energy nexus can be expressed in quantitative terms as follows: 1 kWh of electricity for every 2.4 m³ of water or 1 m³ of water for every 1.5 kWh of electricity. Delhi meets 86.8% of its power needs from the national grid and hence its electricity-related water demand is trans-boundary.
Similar trade-offs are seen between pollution control and the energy footprint of the city’s wastewater infrastructure: open drains consume much less electricity than underground sewers do. Also, the energy footprint nearly doubles if the outlet BOD value decreases from 30 mg/L to 15 mg/L.
Urban areas can lead in the march towards a sustainable civilization because they are the growth engines of economy, enjoy high per-capita income, and possess the requisite skills to bring about such a transition. Further, the case for investment in water infrastructure is also linked to the issue of equity within and outside its boundary if we take virtual water movements into account.
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