![National Board of Fire Under Writer’s formula
Population < 2,00,000
Q = 4637 sq.rt.(P)[1-0.01sq.rt.(p)]
Population > 2,00,000
Q = 54,600 l/min and more 9600 to
36400 l/min](https://image.slidesharecdn.com/lec2-230104070333-355a7ada/85/Lec-2-pptx-20-320.jpg)
Lec 2.pptx
- 1. UNIT 1 Water demand and quantity of water
- 2. Introduction: Quantity ofWater Why to study aboutQuantity ofWater? Toestimate the water demand for the community Todesign the water supply system with long term benefits Todetermine the capacity of the reservoir used in water supply system Tofind the suitable water resources that can meet the demand.
- 3. Water Demand • The rate of water required for a particular town or a city to successfully carry out its day to day activities is known as water demand. • While designing the water supply scheme for a town or city, it is necessary to determine the total quantity of water required. • As a matter it is a first duty of an engineer to determine water demand and then to find a probable source from where the demand can be met.
- 4. Various Quantities need to be assessed • Total annual volume (V) in liters or ML • Annual average rate of draft in lit/day i.eV/365 • Annual avg. rate of draft in lit/day/person called per capita demand • Average rate of draft in lit/day per service i.e. (V/365) X (1/No. of services) • Fluctuations in flows expressed in terms of percentage ratios of maximum or minimum yearly, monthly, daily or hourly rates to their corresponding average values.
- 5. Factors to be known before Designing Water Supply System Population PerCapita Demand ofWater Base and Design period
- 6. Determining quantity of water The quantity of water required for a city can be tackled by twofactors: 1. Rate of demand: The requirements of water for various uses are properly analyzed and ultimately, the rate of consumption per capita per day is calculated. 2. Population: The population to be served by the water supply scheme is estimated and estimate of future population is worked out with help of population forecastmethod.
- 7. 1. Domestic water demand 2. Industrial water demand 3. Institution and commercial water demand 4. Demand for public uses 5. Fire demand 6. Water required to compensate losses in wastes and thefts Types of water demands
- 9. This includes the water requirement of people for drinking, cooking, bathing, lawn sprinkling, gardening, sanitary purposes, etc. The domestic consumption completely depends upon the economic status of the people: 200 lit/head/day for rich living 135 lit/head/day for middle class living •The total domestic demand is equal to 50-60% of the total water consumption.
- 10. Use Consumption in litres per head per day Drinking 5 Cooking 5 Bathing 75 Washing clothes 25 Washing of utensils 15 Washing and cleaning of houses and residences 15 Lawn watering and gardening 15 Flushing of water closets, etc. 45 TOTAL 200
- 11. Use Consumption in litres per head per day Drinking 5 Cooking 5 Bathing 55 Washing clothes 20 Washing of utensils 10 Washing and cleaning of houses and residences 10 Flushing of water closets, etc. 30 TOTAL 135 Minimum Domestic water consumption for weaker sections and LIG colonies in small Indian towns and cities
- 12. The quantity of industrial water demand will vary with the type and number of industries. In industrial cities the per capita water demand computed as 450 l/h/day for high scale industrial zones and as 50 l/h/day for small scale industrial zones.
- 13. S. No. Name of industry and product Unit of production or raw material used Appropriate quantity of water required per unit of production or raw material in kilo litres 1 Auto mobiles vehicle 40 2 Distillery (Alcohol) Kilo litre 122-170 3 Fertilizer Tonne 80-200 4 Leather (tanned) Tonne 40 5 Paper Tonne 200-400 6 Special quality paper Tonne 400-1000 7 Petroleum refinery Tonne 1-2 8 Steel Tonne 200-250 9 Sugar Tonne 1-2 10 Textile Tonne 80-140
- 14. The water requirements of institutions, hospitals, hotels, restaurants, schools, offices, etc. come under this category. The quantity will vary with the nature of the city and with the number and type of commercial establishments. On an average, a per capita demand of 20-50 l/h/day is usually considered for such demand.
- 15. Indivisual water requirement S. No. Type of Institution or Commercial establishment Avg demand in l/h/d 1 offices 45-90 2 Hostels 135-180 3 Restaurants 70 per seat 4 schools a) day school 45-90 b) Residential 135-225 5 Factories a) Where bath rooms are provided 45-90 b) No bath rooms provided 30-60 6 Hospitals ( Including laundry) a) beds less than 100 340 per bed b) beds more than 100 450 per bed 7 Nurses homes & medical quarters 135-225 8 Cinema hall 15 9 Airports 70 10 Railway station 23-70
- 16. This includes the quantity of water required for public utility purposes, such as Watering of public parks Gardening Washing and sprinkling on roads Use in public fountains, etc. A figure of 10 l/h/day is usually considered for this demand.
- 17. PurposeWater Public parks Street washing Sewer cleaning Requirements 1.4 litres/m2/day 1.0-1.5 litres/m2/day 4.5 litres/head/day The requirements of water for public utility shall be taken as…
- 18. In thickly populated and industrial areas, fires generally break out and may lead to serious damages, if not controlled effectively. There fore, a provision should be made in modern water supply schemes for fighting fires. The quantity of water for extinguishing fires, should be easily available and kept always in storage reservoirs. Fire demand
- 19. Kuichling’s formula: Q = 3182 √𝑃 where, P = Population Q = Quantity of water demand Freeman’s formula: 10 Q = 1136 𝑃 + 10 where, P = Population Q = Quantity of water demand
- 20. National Board of Fire Under Writer’s formula Population < 2,00,000 Q = 4637 sq.rt.(P)[1-0.01sq.rt.(p)] Population > 2,00,000 Q = 54,600 l/min and more 9600 to 36400 l/min
- 21. Loses and wastes • Losses due to defective pipe joints, cracked and broken pipes, faulty valves and fittings. • Losses due to, continuous wastage of water. • Losses due to unauthorised and illegal connections. • While estimating the total quantity of water of a town; allowance of 15% of total quantity of water is made to compensate for losses, thefts and wastage of water.
- 22. Water Consumption forVarious Purposes Types of Normal Average % Consumption Range (lit/capita/da y) 1 Domestic Consumption 65-300 160 35 2 Industrial and Commercial Demand 45-450 135 30 3 Public Uses including Fire Demand 20-90 45 10 4 Losses and Waste 45-150 62 25 38
- 23. Per Capita Demand ofWater • Average quantity of water consumption or water demand for various purposes per person per day • Usually expressed in liters per capita per day(lpcd) V P ×365 • Per Capita demand in lpcd = Where, V= total quantity required per year in litres P= population It varies from person to person, place to place and time to time • Water demands in liters/d= Per capita demand ×Population
- 24. Break up of Per Capita Demand for an Average Indian City USE Demand in l/h/d Domestic use 200 Industrial use 50 Commercial use 20 Civic use or public use 10 Wastes & thefts, etc 55 Total 335 = per capita Demand (q)
- 25. Factors affecting per capita demand 1. Size of the city: Per capita demand for big cities is generally large as compared to that for smaller towns . 2. Presence of industries & commercial activities 3. Climatic conditions 4. Habits of people and their economic status 5. Pressure in the distribution system 6. Quality of water supplied 7. Development of sewerage facility 8. System of supply 9. Cost of water 10. policy of metering & Method of charging
- 26. 11. Quality of water: If water is aesthetically & medically safe, the consumption will increase 12. Efficiency of water works administration: Leaks in water mains and services; and unauthorized use of water can be kept to a minimum by surveys. 13.Cost of water. 14. Policy of metering and charging method: Water tax is charged in two different ways: on the basis of meter reading and on the basis of certain fixed monthly rate.
- 27. FACTORE AFFECTINGTHEWATER DEMAND Big city • Size of the city Small towns Example: Delhi 244 l/c/d Vijayawada 135 l/c/d • Climate condition less in winter more in summer • Cost of water rate demand rate demand
- 28. • Supply system Bad Supply • Distribution System Good supply demand Pressure high Pressure low demand demand demand
- 29. • Industry • Quality of water good demand demand bad demand demand industry industry • Habit of people EWS demand MIG demand (Living style)
- 30. Variations in demand and its effects on design of components of water supply scheme • Variations in demand : • Seasonal variation : • Water Consumption :Winter , Summer, Rainy season • DailyVariations • Household & industrial activity. • Water consumption – more holidays • Hourly variations: • Assessment of normal variations : to design supply pipes , service reservoirs , distributary pipes etc..
- 31. Design Periods & Population Forecast This quantity should be worked out with due provision for the estimated requirements of the future . The future period for which a provision is made in the water supply scheme is known as the design period. It is suggested that the construction of sewage treatment plant may be carried out in phases with an initial design period ranging from 5 to 10 years excluding the construction period.
- 32. Design period is estimated based on the following: •Useful life of the component, considering obsolescence, wear, tear, etc. •Expandability aspect. •Anticipated rate of growth of population, including industrial, commercial developments & migration-immigration. •Available resources. •Performance of the system during initial period.
- 34. Population forecasting Design of water supply and sanitation scheme is based on the projected population ofa particular city, estimated for the design period. Any underestimated value will make system inadequate for the purpose intended; similarly overestimated value will make it costly. Changes in the population of the city over the years occur, and the system should be designed taking into account of the population at the end of the design period. Factors affecting changes in population are: increase due to births decrease due to deaths increase/ decrease due to migration
- 35. Population forecasting Methods 1. ARITHMETICAL INCREASE METHOD 2. GEOMETRICAL INCREASE METHOD (ORGEOMETRICAL PROGRESSION METHOD 3. INCREMENTAL INCREASE METHOD 4. GRAPHICAL METHOD 5. COMPARATIVEGRAPHICALMETHOD 6. MASTER PLAN METHOD 7. LOGISTICCURVEMETHOD
- 36. ARITHMETIC INCREASE METHOD This method is suitable for large and old city with considerable development. If it is used for small, average or comparatively new cities, it will give lower population estimate than actual value. In this method the average increase in population per decade is calculated from the past census reports. This increase is added to the present population to find out the population of the next decade.Thus, it is assumed that the population is increasing at constantrate. Hence, dP/dt = C i.e., rate of change of population with respect to time is constant. Therefore, Population after nth decade will be Pn= Po+ n.x Where, Pn is the population after ‘n’ decades and ‘P’ is present population
- 42. GRAPHICAL METHOD In this method, the populations of last few decades are correctly plotted to a suitable scale on graph. The population curve is smoothly extended for getting future population. This extension should be done carefully and it requires proper experience and judgment. The best way of applying this method is to extend the curve by comparing with population curve of some other similar cities having the similar growth condition.
- 45. MASTER PLAN METHOD • The big and metropolitan cities are generally not developed in haphazard manner, but are planned and regulated by local bodies according to master plan. • The master plan is prepared for next 25 to 30 years for the city. • According to the master plan the city is divided into various zones such as residence, commerce and industry. • The population densities are fixed for various zones in the master plan. From this population density total water demand and wastewater generation for that zone can be worked out. By this method it is very easy to access precisely the design population.
- 46. LOGISTIC CURVE METHOD • This method is used when the growth rate of population due to births, deaths and migrations takes place under normal situation and it is not subjected to any extraordinary changes like epidemic, war, earth quake or any natural disaster, etc., • and the population follows the growth curve characteristics of living things within limited space and economic opportunity. • If the population of a city is plotted with respect to time, the curve so obtained under normal condition looks like S-shaped curve and is known as logistic curve.