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SWITCH Training Kit: Pilot Training, Entebbe, 28-29 July 2010
Water Demand Management in the City of the Future
Forecasting water demand – why is accurate demand forecasting important?
Why demand forecasting?
To develop a projection or ‘reference case’ of future water demand in a given region
To help understand the gap between supply and demand Time
Water Surplus
DeficitGap
Average Demand and Peak Demand Demand management is mainly concerned
with consumption of water resource per yearo i.e. average demand
Short-term fluctuations in demand o Time of year / temperature (higher in hot periods)o Days of the week (variation in commercial /
institutional / industrial / household / tourism uses)o Time of dayFluctuations in demand often managed using storagePeak demand determines system design, and
management of peak demand may be valuable
Historical demand forecasting Historical/current per person water demand (l/p-d)
o Historical growth in demand Forecast water demand by multiplying the per person
demand by projected population It is a quick and easy method Limitations
o Only projecting current/past situation which may have been affected by ‘other factors’ such as climate
o Does not account for changes in consumption Changes in use – e.g. showers, flush toilets, washing m/cs Changes in technology and efficiencies
End-use analysis Separate water demand into different sectors (e.g.
residential, industrial) Separate residential into end uses (e.g. showers,
toilets) and estimate change over time Benefits
o Detailed understanding of ‘how’ water is used and how this may change over time
o Uses the concept of the ‘unit of service’ and not just ‘supplying a volume of water’
Limitationso Data on end uses may not be availableo Full analysis requires a major effort (but useful results
and priorities may be obtained through limited study)
Data collection for demand forecasting
The System – Service Provider Bulk
waterMetered water
Other supplies
The System – The customer Demographic data
Stock data
End-use data
•Surveys•Other Govt Statistics
•Questionnaires•Surveys•Data loggers•Diaries•Other studies
•Surveys•Other Govt Statistics
•Surveys
Residential end-uses to consider / collect data for analysis
Indoor end useso Toileto Batho Showero Wash basino Laundry tapo Washing machineo Kitchen tapo Dish washer
Outdoor end useso Lawn/garden irrigatno Livestock o Car washingo Pool etco Evaporative AC
Home business useo Tea shop, Hair
salon, Brewing etc