Ιn water resources management we need a rough estimation of the drinking water demand. We need to know much water will be consumed in an area in order to plan how much water to collect and transfer to that area. We are not concerned about the daily variation of the demand. We are also not concerned about the spatial variation of the demand within a city. We only need to figure out how much water the area will need and decide where we can get this water from.
Example Question.
Assume that a city is growing very fast and it will reach its peak in the year 2050. You work for the water development agency responsibly for that area that includes that city. Name three reasons why it is important to estimate the water demand of the city in 2050.
We need will first need to estimate how much the annual water demand will be in the year 2050 and then plan how to cover this demand. Are there nearby rivers to get water from there? If so, do we need to build a dam to store the high winter flow and used it in the summertime? How big this dam should be? Can we get the required water from an aquifer? For all possible questions, the main most important parameter is the demand.
When estimating the drinking water demand we can break it into three consitues:
- Domestic Water consumption
- Industrial water consumption
- Touristic water consumption
3.2.1.Domestic water consumption
Average water consumption per person ≈ 200 L/day (all-year-round)
We can easily estimate the annual water demand of a city by multiplying its population with the 200 L/day value and then multiplied with 365 (days in a year).
Question: The population of a city is 14 000. Which of the below is a reasonable annual drinking water consumption for that city
- 3000 MCM
- 50 MCM
- 1 MCM
- 60 MCM
The 200 L/day per person is a rough estimate that takes into account
– the consumption at households
– the consumption at commercial building (offices, retail shops, etc)
– the consumption at public spaces (public services building, theaters, etc)
– the water losses in the water distribution system
3.2.2. Touristic water consumption
– Tourist water consumtion can be assumed equal to 300 L/d/κλίνη
The following table shows more exact values for hotel water consumtions according to the stars of the hotels found at the area under consideration.
3.2.3. Industrial Water Consumption
An estimate of the industrial water consumption can be taken from:
(a) historic records of industrial consumption at similar industrial areas
(β) from relevant litterature