While planning a water supply scheme, it is necessary to find out only the total yearly demand but also to assess the required average rate of flow and their variation.
Type of demand :
Water use varies from city to city depending upon the climatic, characteristics of environment, industrialization and other factors in the given city. Water use varies from season to season, day to day and hour to hour. Thus, planning the water supply scheme, the portable water use and its variation must be estimated as much as possible.
Following are the various types of water demand :
- Domestic water demand
- Institutional water demand
- Fire water demand
- Commercial water demand
- Demand for public use
- Compensate losses in water or waste water.
Per capita demand:
It is the annual average amount of daily water requirement by person and includes domestic use. IT is expressed in lit/day.
Per capita element= Total water requirement (litre)/365*designed population
Factors affecting water use
- Dry climate
- Characteristics concern
- Environmental of population
- Industry and commerces
- Pressure in distribution system
- Water rates and metering
Problem no .1:
For this given information analysis the water supply situation of the given municipality also discusses the new project of meeting the demand upto 2085 B.S.
Name of municipality: Kritipur
Population= 120150( 2068 A.D.)
Population grow rate per year = 4.1%
Present situation of water supply
| S.N. | Name of project | Amount of water (HCT) |
| 1. | Sundarighat ground water supply project | 5 million liter/day |
| 2. | Dudh pokhari water supply project | 5 million liter/day |
After 2068 situation of water supply
| S.N. | Name of project | Amount of water | Expected comp |
| 1. | Melachmi water supply project | 10 million lit/day | 2075 |
| 2. | Darighat ground water supply | 5 million lit/day | 2080 |
Capital demand = 135 lit/day/person by Kathmandu
For 2068, population = 120/50
Water demand= 120/50*135
= 16220250 lit/day
For 2071
PT= Po (1+R/100)T
= 120/50(1+4.1/100)3
= 135542.647
Water demand= 135543*135
= 18298305 l/day/person
For 2075
PT= PO(1+R/100)T
= 135543(1+4.1/100)4
= 159176.88
= 159177
Water demand = 159177*135
= 24488895 L/day/person
For 2080
PT= PO(1+4.1/100)T
= 1591767(1+4.1/100)5
= 194596.019
Water demand= 194596*135
= 226270460
For 2085
PT=PO (1+R/100)T
= 194597(1+4.1/100)6
= 237897
Water demand= 237897*135
= 32115960
RESULT AND DISCUSSION
As the population of Kritipur was increased by 4.1% each year. It is increasing at the rate of 4.1% . In the early days, the demand for water was very low compared to recent days.
Water supply is down mainly from rivers, lakes and groundwater. Water consumption varies widely from place to place. Water demand is directly proportional to the population . So, after 2068 two projects were launched to fulfill the demand for water .