This document provides an overview of water demand management (WDM). It discusses traditional forms of WDM, the scope of WDM measures including reuse and recycling, trends in WDM, and constraints. Key points include:
- WDM aims to promote sustainable and equitable water use practices through approaches like pricing, restrictions, and other demand management techniques.
- The scope of WDM includes reducing losses throughout the water supply chain from abstraction to end use. Measures like reuse and recycling can become effective conservation techniques.
- Trends in water demand vary spatially between regions and over time due to factors like population growth, economic development, and climate change. Analyzing historical trends is important for planning.
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Chapter-Five
Contents of The Chapter;
Introduction to WDM
Traditional forms of WDM
The Scope of WDM Measures
Reuse and Recycling, and Water Loss
Trends in WDM
Constraints of WDM
Prioritization for short- and long-term WD
2. Chapter-Five
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Introduction to water demand management (WDM)
WDM is the adaptation and implementation of a strategy by a water institution to influence
the water demand and usage of water to meet:
economic efficiency,
social development,
social equity,
environmental protection,
political acceptability.
sustainability of water supply and services, and
WDM approaches aims to promote water use efficient, equitable and sustainable practices
and policies.
Simply WDM is getting the most of the water that we have’, while taking into account the
social, political, economic and ecological contexts in which this process takes place
WDM corresponds to use of price, quantitative restrictions and other devices to limit the
demand of water.
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Traditional WDM believe that water needs are “requirements” that
must be met and not the “demands” that are changeable.
Traditionally new facilities and structures are developed using
available sources to meet perceived “increasing” water needs.
This has led to over-use of the resources, over-capitalization,
pollution and other problems of varying severity.
Traditionally water supply design not give attention to demand;
determinants, pricing structures,
and also financial policies is not sustainable.
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The Scope of WDM Measures
The scope of WDM will include any measures that will reduce total amount of
water unwise abstraction from the water source.
This will include measures to reduce;
losses in the purification process,
the bulk transmission system,
is the entire water supply chain from the point of abstraction to the point of usage.
This also includes all levels of distribution management and customer DM and
will include all type of consumers; domestic, agricultural, industrial and institutional
users.
the distribution system,
the consumption by the end user, and
ultimately consumption by the end
consumer.
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Benefits of WDM
Reduces water demands (30% - 50%) with no deterioration in service level.
Significantly reduces capital requirements for expansion of water
supply and lowers operating costs (particularly chemicals and energy)
Reduces generation of pollutants, and therefore the requirements for
new or expanded wastewater treatment systems.
Facilitates expansion of the coverage of available fund
Enhances the development and adoption of new technologies.
Leads to financially sustainable water systems
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Water Reuse and Recycling
Typically water reuse and recycling are defined as the use of waste or no potable water instead
of treated drinking water.
It is technics of filtering or other technologies to remove solids sourced from wastewater (also
known as sewage) or storm water
Water reuse and recycling may, become an effective water efficiency and conservation measure.
Clearly, federal, state, and local codes and permit requirements must be carefully reviewed
before considering such measures.
It has multiple use;
for industry purposes,
for agriculture purposes,
for residential use purposes,
for public open space and drinking water, &
for households (non-drinking),
for drinking,
for GW recharge,
for direct reuse,
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Key Reasons to Recycle Water:
Recycled water can be used for applications that require lower quality water, thus
conserving high quality water for high value uses.
Recycled wastewater is climate independent, and is available any time of year.
The volume of wastewater available for recycling is growing as the state grows.
The recycling process draws on less energy than some other sources, such as desalination.
Recycling improves both short-term and long-term water supply and demand security.
The cost effectiveness of using recycled water better than cost of major new scheme
(technology) to use water.
10. Water loss
2.Commercial loss (Apparent loss) due to;
Metering Errors
Water Robbery
Billing Irregularities
Water loss types
1. Physical loss (Real loss) due to;
Pipe breaks and leaks
Storage overflows
House connection leaks
1. More efficient leak detection
Existing real losses
Economic level
Unavoidable real losses
2. Improved response time for
leak repair
3. Improved system maintenance, replacement,
rehabilitation
4. Pressure management and level
control
Four components of an active real loss management program
11. Four components of Commercial/an active apparent loss management program
2. Reduction of theft by
Education
Legal action
Prepay measures
Pressure limitation
Flow control
4. Reduction of human error
Training
Standardizing
Reporting
Auditing
3. Reduction of computer error by
Auditing
Checking
Routine analysis
Upgrade
1. Reduction of meter error by
Testing,
Sizing
Replacement
Economic level
Unavoidable apparent losses
Existing apparent losses
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Water Loss Reduction Strategies
Increase system efficiency,
Increase end use efficiency,
Promoting distributed sources of supply,
Substitute resource use,
Periodic area-wise network maintenance; valves, street surface boxes, signs, etc.,
are locally inspected, cleaned, made accessible or restored.
Periodic pressure surge measurements and misplaced current measurements; to
maintain the up-to-date situation of performance analysis.
Improve the market on resource usage,
Network monitoring and leakage
control,
Regular network flushing’s & hydrant,
controls;
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Trends in WD: temporal and spatial extent (world, region, countries)
Water resources are being altered due to changes in climate, population,
economic development and environmental considerations.
Global supply of available freshwater is more than adequate to meet all current
and foreseeable water demands, its spatial and temporal distributions are not.
There are many regions where freshwater resources are inadequate to meet
domestic, economic development and environmental needs.
In such regions, the lack of adequate clean water to meet human drinking water
and sanitation needs is indeed a constraint on human health and productivity.
These challenging whole world.
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This can be minimized by;
I. controlling demographic growth, increasing the efficiency of the use of goods
II. studying of trends and relationships between water use, population change, non-revenue water, system
capacity, per capita use, and climate conditions.
III. analyzing daily, weekly, monthly, annual, and multi-year water consumption and to assess historical
trends of water consumption for various service classes (residential, multi-residential, commercial,
irrigation, and summer services).
IV. analyzing water production and storage and trends of reservoirs volume change and supply from the
treatment plant.
V. analyzing trends of average and peak daily demand and average per capita demand.
VI. knowing trends in non-revenue water over the study period and evaluate correlation with demand levels
and time of the year.
The results will also help define feasible service level targets and support decisions on system
operations, capacity planning, and demand management.
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0
1
2
3
4
5
6
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8
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1930 1950 1970 1990 2010 2030 2050
Year
Population
(billions)
and
Annual
Water
Use
(million
m
3
) World Population
Fresh Water Use
Figure 1: Population and temporal Water Demand variation in Rusia
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Constraints in Water Demand Management: (Institutional, Cultural, Economic, Political)
There are many constraints of water use;
losses in the distribution system,
not using social impact assessment to determine net social gains from implementing WDM,
lack of ongoing financial and infrastructure support by government to community-based
WDM committees,
limitation of timing of water use,
not Using water at off-peak times for other purposes to reduces strain on the water delivery
system, and
not able to continue to supply the basic needs of the population during times of drought or
seasonal water shortages.
lower quality, high costly in economic angle,
ignorance about what drives regional economies,
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Constraints:
lack of understanding of the need for
WDM
lack of planning and implementation
skills
lack of appropriate institutions and
funding
weak policy and legal instruments
negative view towards WDM
practical (funds, skills and capacity)
not understood of WDM benefits
supply bias among stakeholders
inappropriate training of
professionals
uninformed or dissatisfied
customers
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Constraints of efficient utilization of water resource in Ethiopia
1. lack of skilled man power
2. lack of modern technology
3. lack of good governance
4. land fragmentation
5. poor policy and strategy
6. Financial problem
7. political macro-economic instability
8. poor infrastructure
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Economic Constraints
Economic constraints related to;
incentives such as repayment, tax
credits and
disincentive such as real cost,
penalties,
Institutional constraints
Policies and Laws
Economic policies, government
regulations, standards on appliance
redesign and marketing:
policy to promote water saving devices
encouraging water savings in industries
Effective public/stakeholder education
and awareness measures
Wise use of water; direct restrictions on
use and etc
A direct means of controlling water
demand and generating revenues to cover
costs,
Complementary to other measures of
water demand management, etc.
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Cultural constraints
Water has great religious significance like;
making it an important cultural symbol
for over half of the world’s population,
The Baptist baptized in the waters,
Moses delivered the Ten Commandments,
• As a result, as holy sites, and
natural GOD gift and etc.
Political constraints
Problems related to the lack of
co-ordination.
Many significant implementation
difficulties have been observed,
primarily relating to political will,
the lack of workable methods of
distributive governance,
the role of law,
and stakeholder participation.
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WDM Prioritization for short- and long-term
The activities are based on short- and long-term needs, and should include both active and
passive conservation.
Long-term WDM; enables a response to permanent/long period shortages, supply fluctuations
and reductions in water use.
Long-term Water Use Efficiency (WUE) programs should be integrated with other resource planning.
WUE strategies include metering, progressive rate setting, water loss control programs,
conservation ordinances, and efficiency refund and replacement programs.
Long-term WDM, consider horizons >or= 20 to 30 years;
building long-lifespan water supply infrastructures such as desalination plants, storages,
or large-capacity inter-basin transfers.
Long term planning, are liable to modify both the customer base and per unit water
consumption.
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Short-Term WDM: respond to temporary shortages or fluctuations in supply, especially those
associated with droughts or other short-term emergencies.
Short-term aims at anticipating water demand over the coming hours, days, or weeks, so as to
optimize the operation of water systems (reservoirs, desalination plants) while factoring in changes
in weather and consumer behaviors.
Short-term demand management can help estimate revenues from water sales and plan short-term
expenditures.
Long and short term Demand management program
included the following
Pricing and billing reform
Leakage detection and repair
Rebates & give-aways for water efficient shower
heads
Point of sale rebate for front loading washing
machines
Discounted residential retrofit
Free water audit for non-residential
customers
A water efficient demonstration house and
garden
Effluent reuse in a new village
A school education program
The model has the capability of being used for watersheds as well as major river systems.
developed to predict the impact of land management practices on water, sediment, and agricultural chemical yields in large, complex watersheds with varying soils, land use, and management conditions over long periods of time.
For simulation, a watershed is subdivided into a number of homogenous sub basins (hydrologic response units or HRUs) having unique soil and land use properties.