Until relatively recently problems with water supply-demand balance were typically addressed through "supply augmentation", that is to say, building more
dam
A dam is a barrier that stops or restricts the flow of surface water or underground streams. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use, a ...
s,
water treatment
Water treatment is any process that improves the Water quality, quality of water to make it appropriate for a specific end-use. The end use may be drinking water, drinking, industrial water supply, irrigation, river flow maintenance, water recrea ...
stations, etc. As long as
water resources
Water resources are natural resources of water that are potentially useful for humans, for example as a source of drinking water supply or irrigation water. 97% of the water on the Earth is salt water and only three percent is fresh water; slight ...
were considered abundant and the needs of the natural environment were ignored this reliance on the "engineering paradigm" made sense. Moreover, water utilities and governments have long preferred large capital projects to the less profitable and more difficult challenges of improving system efficiency (e.g. leakage reduction) and
demand management
Demand management is a planning methodology used to forecast, plan for and manage the demand for products and services. This can be at macro-levels as in economics and at micro-levels within individual organizations. For example, at macro-leve ...
. Water demand management came into vogue in the 1990s and 2000s at the same moment dams and similar supply augmentation schemes went out of fashion because they were increasingly seen as overly expensive, damaging to the environment (see
Environmental impact of reservoirs
The environmental impact of reservoirs comes under ever-increasing scrutiny as the global demand for water and energy increases and the number and size of reservoirs increases.
Dams and reservoirs can be used to supply drinking water, generate hy ...
), and socially unjust. Now, in the 2020s, it is accurate to say that demand management is the dominant approach in the richer countries of North America and Europe, but is also becoming more popular in less affluent countries and regions.
Definitions and approaches
At its heart, demand management is about forecasting demand for good and services and planning how that demand will be met. In many applications demand management is also increasingly about reducing or moderating demand (e.g. water, energy, acute clinical health services, etc.). In energy demand management, for example, the offer of cheaper off-peak energy tariffs is a common method for shifting energy demand away from peak periods and towards periods when there is surplus energy available.
Water demand management depends on better understanding of exactly how much water different users are using for different purposes (the quantitative challenge) and on users' decision-making processes (the qualitative challenge). With these sorts of data it is possible to create policies, at utility scale (usually a city-region) or national scale (government), to promote reductions in user demand. If skilfully done, such policies can address supply-demand imbalances by reducing demand to available supply, though the risk of negative impacts on utilities, consumers and the environment are all too real. There are three basic approaches to water demand management policy and one key challenge, all of which are discussed below with reference to the key sectors where water demand management is practiced: domestic, agricultural and industrial.
Domestic water demand management
Consumer education
All water utilities and most governments now pursue programmes of public education aimed at promoting reductions in water use. Such programmes have increasingly moved on-line, targeting consumers with tweets, Instagram posts and even Tik Toks enthusiastically promoting
water conservation
Water conservation includes all the policies, strategies and activities to sustainably manage the natural resource of fresh water, to protect the hydrosphere, and to meet the current and future human demand (thus avoiding water scarcity). Populati ...
. This is a welcome change from previous approaches based on physical mailshots of enclosures with water bills as there is little evidence that these exercised much influence on water users' behaviours.
An under-recognised challenge with consumer education approaches to demand management is that they tend to assume that water users are always
rational agents
A rational agent or rational being is a person or entity that always aims to perform optimal actions based on given premises and information. A rational agent can be anything that makes decisions, typically a person, firm, machine, or software.
Th ...
, collecting all relevant data and then producing purely rational decisions based on the data. Research into water users' behaviours shows that most decisions are more linked to habit, perception and social conventions than rationality, particularly in the domestic sphere. In agriculture and industry consumer education approaches are less common, as there is a greater reliance on water tariffs and direct state regulation of water abstraction and wastewater return.
Replacement of fixtures and fittings
In city-regions where supply constraints are more severe water utilities have occasionally adopted the approach of offering to replace water-consumptive fixtures and fittings with water-conservative ones. A good example is in south California where worries about running out of water led to a comprehensive programme of consumer education, leak detection, tariff reform and plumbing retrofits. Key to success has been the replacement of over two million high flush volume toilets with low flush volume alternatives. The authority has also supplied more than three million high efficiency showerheads and over two hundred thousand tap/faucet aerators (mixing air with water reduces flow rates whilst maintaining performance). These measures have saved over 66,000 acre-feet (conversion) of water per year, which can then be directed to improving supply-demand balance.
Water tariff/price reform
Many commentators argue that utilities often do not charge prices that encourage users to conserve water. Certainly domestic
water tariff A water tariff (often called ''water rate'' in the United States and Canada) is a price assigned to water supplied by a public utility through a piped network to its customers. The term is also often applied to wastewater tariffs. Water and wastewat ...
s are low in North America and Europe, and indeed in much of the rest of the world. But the drive to discipline user demand by ratcheting up water tariffs brings with it a series of problems. First, available research suggests that there is relatively little "price elasticity of demand" linked to domestic water consumption—estimates vary between about -0.1 and -0.4, meaning that the demand for water decreases by 0.1% to 0.4% for every 1% increase in tariffs. Second, attempts to achieve demand reduction by increasing price can create "water poverty" (usually defined as households spending more than 3-5% of household income on water services). Third, the data and data management required for even simple charging schemes (single volumetric charges) can cost more than the saved water cost to produce in the first place. More complex tariffs (e.g. rising block or seasonal tariffs) require even more expensive and complex data systems that are not yet widespread even in richer countries.
The problem of data
Assessing the efficacy of the above policies, singly or in combination, requires data that is expensive to acquire and complex to manage and process. Moreover, since water consumption is the product of a large number of interacting drivers, constraints and schemes, involving periodic social media or mail-shot communications to consumers promoting water conservation, require sufficiently frequent meter readings (e.g. daily, weekly or monthly) at household scale to be quite expensive to implement. All the more so in countries like the UK where domestic meter penetration is only 60 or 65%. Much enthusiasm has been generated around the prospects that so-called
smart meter
A smart meter is an electronic device that records information such as consumption of electric energy, voltage levels, current, and power factor. Smart meters communicate the information to the consumer for greater clarity of consumption beha ...
s (meters combining measurement, data logging and communications) could greatly facilitate water demand management. To date results are not encouraging, mostly due to the relatively poor state of the required data infrastructure.
Irrigation demand management
Agricultural water use is vastly larger than industrial or domestic water use globally and in most countries, therefore irrigation water demand management is an important topic. As with domestic water demand management lack of appropriate data is a frequently encountered problem signalling the importance of measuring water usage at the farm and distributor level and at appropriate time steps. As an historical aside, there is
evidence
Evidence for a proposition is what supports this proposition. It is usually understood as an indication that the supported proposition is true. What role evidence plays and how it is conceived varies from field to field.
In epistemology, evidenc ...
from both historical and archaeological records of technology development for water allocation and assessment in India, the Arabian Peninsula and Peru.
Two major themes dominate research in irrigation water demand management: attempts to understand, and manipulate, farmers' irrigation decision-making and understanding optimal irrigation strategies for specific crops or environments.
Industrial water demand management
Water demand management in industry is managed primarily through regulation of water abstraction (especially for large industrial water users) and regulation of wastewater discharge. In many countries large water users can apply for permits to directly remove ="abstract"- water from the natural environment for industrial purposes. A common example is the energy industry which requires large volumes of water for cooling purposes in thermal and hydropower electricity generation facilities. In the UK electricity generators are responsible for more than half of all licensed water abstraction. In other countries the proportion of abstraction earmarked for electricity generation varies widely, but it almost always a significant factor in overall water supply demand balance. Many studies of this
water-energy nexus
The water-energy nexus is the relationship between the water used for energy production,Spang, E. S., Moomaw, W. R., Gallagher, K. S., Kirshen, P. H., and Marks, D. H. (2014). "The water consumption of energy production: an international comparison ...
focus on process optimisation or input substitution.
An important part of industrial water demand management is the encouragement of "closed loop" processes within facilities. For example, in textiles production, which uses significant volumes of water for washing and dying, closed loop principles in water use reduce both the total demand for new abstractions and the risk to the natural environment from inadequately treated wastewaters. Such approaches however require significant capital investment, especially in modern multi-stage wastewater treatment, and are not yet universal in textiles facilities around the world.
Current research directions
Since pressures on water suppliers continue to mount, researchers are increasingly focussing on developing the empirical data base underpinning demand management approaches. As noted above, how far researchers can go in large measure depends on data infrastructure and there have been innovations here too. There are increasing numbers of studies that focus on special environments (e.g. university student accommodation, military housing, etc.) and have compiled the required quantitative and qualitative data to robustly assess the impact of demand reduction policies/programmes. There are also ongoing efforts to rigorously determine price elasticity of demand for more generalised residential populations.
There are also new approaches emerging, based on the critique of the mainstream approach's tendency to assume
rational agents
A rational agent or rational being is a person or entity that always aims to perform optimal actions based on given premises and information. A rational agent can be anything that makes decisions, typically a person, firm, machine, or software.
Th ...
as the policy target. In particular,
social practice theory
Practice theory (or praxeology, theory of social practices) is a body of social theory within anthropology and sociology that explains society and culture as the result of structure and individual agency. Practice theory emerged in the late 20th c ...
and the related ISM ("individual, social, material") approaches abandon the idea of
rational agents
A rational agent or rational being is a person or entity that always aims to perform optimal actions based on given premises and information. A rational agent can be anything that makes decisions, typically a person, firm, machine, or software.
Th ...
and focus attention on the co-constitutive interrelations between people deploying materials within complex social frames. These water-mediated interrelations were extensively researched by the "Traces of Water" research project led by Browne, Pullinger and Medd in the first decade of the 21st century.
See also
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Customer demand planning
Customer demand planning (CDP) is a business-planning process that enables sales teams to develop demand forecasts as input to service-planning processes, production, inventory planning and revenue planning.
Definition
CDP is an aspect of mana ...
*
Forecasting
Forecasting is the process of making predictions based on past and present data. Later these can be compared (resolved) against what happens. For example, a company might estimate their revenue in the next year, then compare it against the actual ...
*
Supply and demand
In microeconomics, supply and demand is an economic model of price determination in a Market (economics), market. It postulates that, Ceteris paribus, holding all else equal, in a perfect competition, competitive market, the unit price for a ...
*
Water conservation
Water conservation includes all the policies, strategies and activities to sustainably manage the natural resource of fresh water, to protect the hydrosphere, and to meet the current and future human demand (thus avoiding water scarcity). Populati ...
*
Water security
Water security is the focused goal of water policy and water management. A society with a high level of water security makes the most of water's benefits for humans and ecosystems and limits the risk of destructive impacts associated with water. T ...
*
water supply and sanitation in Malaysia
Water supply and sanitation in Malaysia is characterised by numerous achievements, as well as some challenges. Universal access to water supply at affordable tariffs is a substantial achievement. The government has also shown a commitment to mak ...
*
Cape Town water crisis
The Cape Town water crisis in South Africa was a period of severe water shortage in the Western Cape region, most notably affecting the City of Cape Town. While dam water levels had been decreasing since 2015, the Cape Town water crisis peaked d ...
References
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Water management
Demand management