Lecture 2 Flashcards
What is the Seasonal Peak Factor in Nepal
1
What is the Daily Peak Factor in Nepal
1
What is the Hourly Peak Factor in Nepal
3
Maximum Seasonal Demand formula
Maximum Seasonal Demand = Seasonal Peak Factor * Annual average demand
Maximum Daily Demand formula
Maximum Daily Demand = Daily Peak Factor * Annual average demand
Maximum Hourly Demand formula
Maximum Hourly Demand = Hourly Peak Factor * Annual average demand
Peak Factor definition
Ratio of the maximum demand to that of average annual demand of water
Peak factor formula
Peak factor = Seasonal peak factor * Daily Peak Factor * Hourly Peak factor.
Peak factor for continuous system
2-4
Peak factor for intermittent system
4-6
Maximum demand formula
Maximum demand = Peak factor * Annual average demand
Base Period definition
Base period is the period required for survey, design and construction of water supply system. Usually, base period of two to three years is adopted
Design Period definition
Design period is defined as the future period for which a provision is made while planning and designing the water supply programs. Usually, 15 to 20 years is adopted as design period.
Base period how many years
15 to 20 years
Design period how many years
2 to 3 years
How to select design period
Anticipated expansion rate of the town:
If r ≥ 2, design period is 15 years
If r < 2, design period is 20 years
(r=growth rate of population)
Arithmetical increase method formula
Pn=Po+nC
Pn= Population after ‘n’ decades
Po=Last known population
C=Average (arithmetic mean) of increase in population
Geometrical increase method formula
Pn = Po(1+r/100)^n
Pn=Population after ‘n’ decades
Po=Last known population
r=average percentage increase in population
Incremental Increase Method formula
Pn = Po+nc+n((n+1)/2)*i
Pn=Population after ‘n’decades
Po = No. of present (last known) population n = No. of decades
c = Average (arithmetic mean) of increase in population
i = Average incremental increase
Decreasing rate of growth
??
Fire demand limit of lpcd
Not more than 11lpcd
National Board of Fire Underwriter’s formula
Q = 4637sqrt(P)(1-0.001*sqrt(P))
Q = quantity of water in l/min
P = Population in thousands
J.R. Freeman’s formula
Q = 1136*((P/5)+10)
Q = quantity of water in l/min
P = Population in thousands
Kuilching’s formula
Q = 3182*sqrt(P)
Q = quantity of water in l/min
P = Population in thousands
Buston’s formula
Q = 5663*sqrt(P)
Indian water supply manual (1976) formula
Q = 100*sqrt(P)
Q = quantity of water in m^3/day
P = Population in thousands
Compensate losses demand
15-20% total demand for city.
50% in Kathmandu Valley.
In metered supply it is 30%
In un-metered supply it is 50%.
Zero in rural
Per Capita Demand or rate of demand formula
q = Q/(365*P) (in lpcd)
Q = quantity of water required per year by town (litres)
P = Population of town at the end of design period
Base year definition
The year in which the water is delivered to the community
Base year = Survey year + Base Period
Design Year definition
The year for which the water supply system is designed for
Design Year = Base year + Design Period
Selection Basis of Design Period
- Fluid Available
- Development of community
- Population Growth rate
- Availability of funds and rate of interest
- Useful life of components
Commercial Demand (CD) definition
Commercial Demand includes the demand of water by offices, restaurants, schools, colleges, hospitals, hotels and other institutions.
CD for offices
500-1000 lits/day for offices (Depending upon the size)
CD for hospitals with the bed
500 lits/bed/day
CD for hospitals without bed and health clinics
2500 lits/day
CD for hotels with the bed
200 lits/bed/day
CD for hotels without the bed
500 - 1000 lits/day
CD for for restaurants and tea stalls
500 – 1000 lits/day
CD for day scholars
10 lpcd
CD for boarders
65 lpcd
Total Water Demand formula
Total water Demand = DD + LD + CD + PD + ID + FD + LW
Fire Demand (FD)
The quantity of water that is required for firefighting purposes.
Loss and Wastage (LW)
15% of total supply. The loss of water
may be due to leakage in valves, mains, unauthorized connections, fittings, etc.
Industrial Demand (ID)
20-25% of total consumption. Water consumed by industries is included within the industrial demand. 20-25% of the total consumption is made for industrial demand.
Public/Municipal Demand (PD)
5-10% of total consumption. Public Demand includes the quantity of water required for watering of public parks and gardening purposes. It includes cleaning of roads and sewers. This demand is taken into consideration in urban communities only.
Livestock Demand (LD)
Livestock demand includes the quantity of water consumed by domestic animals and birds as cows, buffalos, horses, sheep, goat, pigs, chicken, ducks, etc.
LD for big animals such as cows, horses etc
45 lits/animal/day
LD for medium sized animals as pigs, sheep, goats, etc.
20 lits/animal/day
LD for birds such as chicken ducks, etc.
20 lits/100birds/day
