Unit - 1

Basics of Water Supply Engineering

1.1 Introduction to Water supply scheme:

• Water deliver is the availability of water through public utilities, industrial organizations, network endeavors or through individuals, generally thru a device of pumps and pipes.
• Aspects of carrier exceptional consist of continuity of deliver, water exceptional and water pressure. The institutional duty for water deliver is organized in a different way in distinct nations and regions (city as opposed to rural). It generally consists of problems surrounding coverage and regulation, carrier provision and standardization.
• The price of providing water consists, to a totally huge quantity, of constant charges (capital charges and employee’s charges) and most effective to a small quantity of variable charges that rely on the quantity of water consumed (specially electricity and chemicals).
• Almost all carrier companies with inside the global price lists to get better a part of their charges. Water deliver is a separate subject matter from irrigation, the exercise and structures of water deliver on a bigger scale, for a greater diversity of purposes, commonly agriculture.
• Water delivery system, infrastructure for the collection, transmission, treatment, storage, and distribution of water for homes, industrial establishments, industry, and irrigation, in addition to for such public wishes as firefighting and road flushing. Of all municipal services, provision of potable water is possibly the maximum vital.
• People rely on water for drinking, cooking, washing, sporting away wastes, and different home wishes. Water delivers structures have to additionally meet necessities for public, industrial, and commercial activities. In all cases, the water have to satisfy each pleasant and amount necessities.
• Water became a crucial aspect with inside the area of the earliest settled communities, and the evolution of public water deliver structures is tied at once to the boom of cities.
• In the improvement of water assets past their herbal circumstance in rivers, lakes, and springs, the digging of shallow wells became probable the earliest innovation. As the want for water improved and gear have been developed, wells have been made deeper.
• Brick-covered wells have been constructed via way of means of town dwellers with inside the Indus River basin as early as 2500 BCE, and wells nearly 500 meters (greater than 1, six hundred feet) deep are recognized to had been utilized in historical China.
• Construction of quants, barely sloping tunnels pushed into hillsides that contained groundwater, probable originated in historical Persia approximately seven-hundred BCE. From the hillsides the water became conveyed via way of means of gravity in open channels to close by cities or cities.

Key takeaways:

• The price of providing water consists, to a totally huge quantity, of constant charges (capital charges and employee’s charges) and most effective to a small quantity of variable charges that rely on the quantity of water consumed (specially electricity and chemicals).

1.2 Importance of Water Infrastructure and introduction to water infrastructure in India:

• The water delivers and sanitation in India has stepped forward significantly from 1980 to present. However, many human beings lack get admission to smooth water, toilets, and sewage infrastructure.
• Various authorities’ packages at national, state, and network degree have introduced speedy upgrades in sanitation and the consuming water deliver. Some of those packages are ongoing.

The reason that responsible to make water infrastructure:

A form of interrelated factors are involved, including:

• Water is an ignored and marginalized sector of infrastructure, in contrast with others. Water does now not enjoy high-quality political assist and has fewer “champions” than exclusive sectors.
• Water infrastructure is capital-significant and its development consists of an extended planning and implementation cycle.
• Water prices are generally too low to cover on-going charges, sooner or later operators rely on state fee variety subsidies. This makes water unattractive to commercial reasserts of finance and discourages private operators.
• Water infrastructure is costly, and its heavy funding desires are hard to fulfill from national financial reasserts. However, financing opportunities are setting up.
• Long term finance for infrastructure has been greater tough to raise while you bear in mind that 2008, and many countries keep to war with macroeconomic and monetary pressures which constrain investment. At the same time, now might be an exquisite time to enhance funding for infrastructure while you bear in mind that borrowing charges are at incidental lows.
• A growing chorus of influential voices are arguing in favor of government borrowing for infrastructure development: a globally coordinated try of infrastructure investment is probably a prime enhance to international growth.
• Treatment procedures normally feature both via the bodily elimination of contaminants via filtration, settling (frequently aided via way of means of a few shapes of chemical addition) or organic elimination of microorganisms.
• It is traditional for remedy to be in some of stages, with preliminary pretreatment via way of means of settling or pre-filtration via coarse media, sand filtration (speedy or slow) accompanied via way of means of chlorination.
• This is referred to as the couple of barrier principle. There are many distinct remedy methods to be had and whose suitability is a feature of the supply water quality, stage of operator schooling and sources to be had for operation and maintenance.
• It is vital that the choice of era for remedy plant life is completed taking the above into attention to make certain that they stay sustainable.

Water infrastructure in India

Protect the Source

Maintaining water Resources Now and into the future

1. Practice Conservation

One of the best ways to ensure sustainable water resources for the future is to practice conservation and smart water use practices today.

2. Support Watersheds

Watershed health is essential to protecting water supply. Most water infrastructure spending focuses on built infrastructure, but investment in watershed conservation is essential to ensure water security.

3. Ensure Quality

From source to faucet to waste, maintaining water quality requires an intersectional approach. Contaminants can enter waterways from runoff, groundwater pollution and older infrastructure.

4. Grow Green Infrastructure

Green infrastructure is an important part of how drinking, wastewater, stormwater agencies can provide innovative, effective, affordable water services.

Key takeaways:

• Water is an ignored and marginalized sector of infrastructure, in contrast with others. Water does now not enjoy high-quality political assist and has fewer “champions” than exclusive sectors.

1.3 Data collection required for implementing water supply schemes, components and layouts:

Fig. 1: Data collection

• A water deliver community or water deliver gadget is a gadget of engineered hydrologic and hydraulic additives that offer water deliver.
• A water deliver gadget generally consists of the following: A drainage basin (see water purification – reasserts of consuming water) A uncooked water series point (above or underneath ground) wherein the water accumulates, inclusive of a lake, a river, or groundwater from an underground aquifer. Raw water can be transferred the usage of exposed ground-degree aqueducts, protected tunnels, or underground water pipes to water purification centers.
• Water purification centers. Treated water is transferred the usage of water pipes (normally underground). Water garage centers inclusive of reservoirs, water tanks, or water towers. Smaller water structures can also additionally shop the water in cisterns or stress vessels. Tall homes might also want to shop water domestically in stress vessels so as for the water to attain the top floors.
• Additional water pressurizing additives inclusive of pumping stations can also additionally want to be located at the hole of underground or aboveground reservoirs or cisterns (if gravity float is impractical).
• A pipe community for distribution of water to consumers (which can be non-public homes or industrial, commercial, or group establishments) and different utilization points (inclusive of hearth place hydrants) Connections to the sewers (underground pipes, or aboveground ditches in a few growing countries) are usually observed downstream of the water consumers, however the sewer gadget is taken into consideration to be a separate gadget, instead of a part of the water deliver gadget.

Key takeaways:

• Water purification centers. Treated water is transferred the usage of water pipes (normally underground). Water garage centers inclusive of reservoirs, water tanks, or water towers. Smaller water structures can also additionally shop the water in cisterns or stress vessels.

1.4 Components of water supply scheme:

Fig 2. Components of water supply scheme

• That part of a public water device transporting water from the remedy plant to the customers is referred to as the distribution device. Physical elements consisting of the design, creation. And operation of such structures may have critical effects on water high-satisfactory.
• The complexity of and needs on those structures lead them to the maximum pricey unmarried detail with inside the water deliver device. To keep away from feasible infection and due to the fact it's far brought to the customers below stress, handled or completed water is transported in conduits or pipes instead of with the aid of using open channels.
• In addition to a community of interconnecting mains or pipes, water distribution structures commonly consist of garage centers, valves, hearth place hydrants, provider connections to person centers, and possibly pumping centers. The cap potential of a distribution device to supply an good enough amount of water to fulfill the prevailing and projected needs of the domestic, business, and business customers and to offer the vital waft for hearth place safety relies upon the wearing ability of the device's community of pipes.
• In all however the most important structures. The waft this is vital to fight a first-rate hearth place is typically the principal component figuring out necessities for the quantity of water to be saved, the scale of mains with inside the device, and the stress to be maintained. Fire waft requirements require a minimal residual water stress of 20 kilos consistent with rectangular inch gauge (psig) for the duration of waft.
• It is not unusual place exercise to keep pressures of 60 to seventy-five psig in business and business regions and 30 to 50 psig in residential regions. Distribution device mains and pipes have to be designed to face up to those pressures.
• The waft of water distribution structures can be managed both with the aid of using gravity or with the aid of using stress (pumping). Often, public water deliver structures use a few aggregate of both.
• In gravity structures, water is impounded at strategic places sufficiently improved to create the running stress required to transport the water to the factors of call for. When improved impoundment or garage is impractical, the specified running stress is supplied with the aid of using pumps with inside the device. In those stress structures, the pumps are commonly positioned on the remedy plant and possibly with inside the distribution device. In blended structures, centers for water garage are frequently supplied together with provision for pumping.
• This kind of device offers for the garage of water for the duration of instances of least call for even as assuring that a enough amount is to be had to fulfill the height call for.
• Typically, water is pumped immediately into the distribution device. The amount of water exceeding the call for routinely feeds right into a garage facility or reservoir. A device can also be designed in order that pumps deliver the water garage facility immediately; the water, in turn, would possibly circulate the distribution device with the aid of using gravity. Reservoirs can be positioned at the start of a distribution device, i.e., right now following water remedy, or at an intermediate factor with inside the device.
• The saved water can be used to fulfill fluctuating needs or to equalize prices of waft or running pressures at the device. The reservoirs can be categorized as underground, floor stage, improved, or standpipe. An underground reservoir or basin, both open and protected, can be at or under grade stage and fashioned both with the aid of using excavation or embankment.
• It is standard to line such reservoirs with concrete, Unite, asphalt or an asphalt membrane, or butyl rubber. A standpipe includes a cylindrical shell with a flat backside resting on a basis at floor stage. An improved reservoir is a tank supported above floor with the aid of using a structural framework. Steel and timber were used with inside the creation of standpipes and improved tanks, which might be commonly protected.
• It is most desirable to apply protected reservoirs for handled water due to the fact water in open reservoirs is problem to falling dust, dust-borne microorganisms, and soot; to infection with the aid of using animals, inclusive of birds and human beings; and to algal increase.
• It can be vital to manipulate algae and microbial slime growths in open distribution reservoirs with the aid of using including copper sulfate and/or chlorine to the water. Furthermore, to make certain good enough disinfection, it's far usually believed that there have to be an enough chlorine residual at some stage in the distribution device. In a massive distribution device, chlorination of the water can be required. This is frequently executed on the distribution reservoirs.

Key Takeaways:

• The waft of water distribution structures can be managed both with the aid of using gravity or with the aid of using stress (pumping). Often, public water deliver structures use a few aggregate of both.

1.5 Layouts required for water supply scheme:

• From the technical factor of view, the subsequent 3 fundamental questions must be replied for the duration of the making plans segment of a water deliver scheme:
• Which uncooked water supply need to be used for the water deliver scheme?
• If remedy is necessary, what form of remedy scheme need to be favored?
• How plenty water need to be disbursed to the consumers, and at what carrier level?
• Source choice is a completely primary selection entailing several results for the destiny water deliver scheme. The exceptional nearby water reassess must be evaluated with recognize to their quantity, exceptional and accessibility. The destiny water call for ought to be included with the aid of using the chosen supply with the high-satisfactory viable water exceptional, and placed as near as viable to the deliver area.

Fig. 3: Layout required for water supply scheme

• Since water remedy is normally the maximum tough detail in any water deliver scheme, it has to be prevented every time possible. The preferred assertion that no remedy is the nice remedy specially applies to rural water deliver schemes which usually showcase a terrible infrastructural and institutional framework to safely hold water remedy facilities. The use of higher water pleasant reassess is, consequently, an opportunity with the intention to continually need to be taken into critical consideration.
• If no different opportunity is available, rural water remedy should focus on enhancing the bacteriological water pleasant through regionally sustainable remedy processes.
• Water distribution structures rely upon the kind of water supply used, at the topography, and at the furnished deliver provider stage. Individual water supplies, e.g. Rainwater harvesting and shallow groundwater wells geared up with hand pumps normally do now no longer want piped deliver structures. Treated floor water, however, is commonly dispensed through a piped gadget.
• An appropriate topography regularly lets in the setup of a gravity gadget with the intention to enhance reliability and deliver continuity. Since pumped water deliver schemes rely upon the dependable deliver of strength and spare parts, they may be very liable to brief standstills. Finally, the provider stage of water deliver strongly governs water demand.
• Water utilization will increase notably with the furnished provider stage, e.g. Public stand post, backyard connection, a couple of faucet residence connection. Water deliver is continually interlinked with wastewater disposal. The fitness scenario of a network furnished with handled water does now no longer always enhance, especially if public fitness and wastewater disposal problems are neglected.
• The important additives important to noticeably enhance the general public fitness scenario of a network are consequently a dependable and secure water deliver, an good enough waste disposal gadget and a complete hygiene schooling programmer.
• As schematized in Fig., floor water needs to be collected, handled and saved earlier than it reaches the consumer. These sports may be met through specific water deliver format options. Figs. 15 and sixteen most effective illustrate a few association examples.

Key takeaways:

• If no different opportunity is available, rural water remedy should focus on enhancing the bacteriological water pleasant through regionally sustainable remedy processes.

1.6 Design periods: factors affecting design periods

• Design duration might be described because the range of years with inside the close to destiny wherein the deliver will surpass the demand. Or, it is the range of years with inside the close to destiny wherein the given facility is offered to meet the demand.
• The water supply of any settlement covers huge dams to develop a reservoir.
• The water treatment plant is constructed with huge network of pipelines to search the consumers. As the population goes on increasing the demand of water is also increasing but it is not easy change existing water supply scheme or to increase its capacity.

The major motives at the back of presenting Design Periods are:

• It is prodigiously strenuous or unfeasible to provide frequent.
• It is inexpensive to deliver one immense unit in lieu of building plenty of bijou ingredients.

Factors Affecting the Design Period:

(i)                Useful existence of aspect systems and the possibilities in their turning into vintage and obsolete. Design intervals must now no longer exceed the ones respective values.

(ii)              Ease and problem this is probable to be confronted in expansions, if undertaken at destiny dates. For example, extra hard expansions imply selecting a better fee of the layout length.

(iii)           Amount and availability of extra funding probable to be incurred for extra provisions. For example, if the budget isn’t available, one has to maintain a smaller layout length.

(iv)            Anticipated fee of populace growth, which include viable shifts in communities, industries and business establishments. For example, if the fee of boom of populace is less, a better discern for the layout length can be chosen.

(v)                The fee of hobby at the borrowings and the extra cash invested. For example, if the hobby fee is small, a better fee of the layout length can be economically justified and, therefore, adopted.

Life of the shape

• Life of shape is the wide variety of years in destiny for which the layout duration is bodily appropriate to offer the supposed facility. So, it has to be much less than lifestyles of shape.

Ease or issue in extension

• For the initiatives whose extension is without problems possible, it's far stored low. For instance, we will despoliation new tube wells at any time, so we do now no longer want to put in all tube wells which could be required after 20 years. But for the initiatives whose extension is difficult, their layout duration is stored greater. For instance, dams and reservoirs can't be prolonged without problems.

Rate of populace boom

• If the fee of populace boom is higher, then for that place shorter layout duration is required.

Lead time

• It is the time from the graduation of a task to its completion. Design duration have to be more than lead time.

Economy of scale

• The lower in common value as the scale of facility growth is called financial system of scale. If the financial system of scale is small, smaller layout duration may be used. It is reasonable to construct a huge structure, for longer layout duration.

Performance time

• Structures are checked beneath Neath operating circumstance for some time, which have to now no longer be taken into consideration in layout duration. During this time, it isn't always presenting facility to community.

Key takeaways:

• The water supply of any settlement covers huge dams to develop a reservoir.

1.7 Quantity: Rate of water consumption for various purposes like domestic, industrial, institutional, commercial

Quantity:

• Water amount is the timing and overall yield of water from a watershed, and is measured via way of means of overall yield and height glide over a certain duration of time. Water pleasant is the suitability of water for drinking, leisure uses, and as habitat for aquatic organisms and different wildlife.

Rate of water consumption for various purposes:

Water Quantity Estimation

• The quantity of water required for municipal uses for which the water supply scheme has to be designed requires following data:

1. Water consumption rate (Per Capita Demand in liters per day per head)
2. Population to be served.

Quantity= Per capita demand x Population

Water Consumption Rate

• It is very difficult to precisely assess the quantity of water demanded by the public, since there are many variable factors affecting water consumption. The various types of water demands, which a city may have, may be broken into following classes:
• Water Consumption for Various Purposes:

Factors affecting per capita demand:

a. Size of the city: Per capita call for huge towns is typically massive compared to that for smaller cities as huge towns have skewered houses.

b. Presence of industries.

c. Climatic conditions.

d. Habits of human beings and their financial status.

e. Quality of water: If water is aesthetically as human beings will now no longer motel to non-public wells, etc.

f. Pressure with inside the distribution system.

1.8 Fire demand and water system losses, factors affecting rate of demand, population forecasting, including numerical

Fire demand:

• The water required for unexpected fire accidents and undesirable situation with fire is already designed during the water demand planning system. 
• The demand is calculated based on empirical formulas. For all the formulas given below, Q is the discharge calculated in liters per minute and P is the population measured in thousands.

1. Kuichling's Formula

Q = 3182P1/2

2.     Buston's Formula

Q = 5663P1/2

3.     Freeman's Formula

Q = 1136[0.2P + 10]

4.     National Board of Underwater Formula

Q = 4637P1/2[1 - 0.01P1/2]

Example 1

Compute the fire demand for a city of 2 lakh population by any two formulae (including that of the National Board of Fire Underwriters)

Solution

(i) The rate of fire demand as per National Board of fire Under writers Formula for a central congested city whose population is less than or equal to 2 lakh is given by

(ii) Kuchling’s formula

Example 2 Calculate the fire fighting water requirement by using Bustons formula for a settlement having 10,000 population.

Solution:

Bustons formula:

Q = 5663

Q = The quantity of water required for fire fighting liters/per minute.

Q = 5663

Q = 5663 = 5663100 = 5,66,300

The total water requirement for settlement having 10,000 populations for fire fighting will be 5,66,300 Liters/minute.

Example 3 Using Kuichling formula calculate the water demand for fire dighting for a settlement with 10,000 population.

Solution:

Kuichling formula:

Q = 3182

Where,

Q = Quantity of water / in liters/ per minute

P = Population of the settlement

Q = 3182 = 3183 100

Q = 3,18,200

So, the settlement will require to have 3,18,200 liters water per minute for fire fighting.

Example 4 Find fire demand for a city having population of 20 lakh by Kuichling formula.

Solution:

Kuichling formula:

Q = 3182

Q = 3182

Q = 142.3 lit/min

So, the settlement will require to have 142.3 lit/min water per minute for fire fighting.

Example 5 Find fire demand for a city having population of 20 lakh by Bustons formula.

Solution:

Bustons formula:

Q = 5663

Q = 5663

Q = 253. 25 lit/min

Factors affecting rate of demand:

1. Climatic Conditions:

• The requirement of water is extra at locations having warm and dry weather than at locations having bloodless and humid weather. This is so due to the fact at locations having warm and dry weather extra water is needed for bathing, washing of clothes, air coolers, air conditioning, garden watering, gardening, etc. Similarly, the requirement of water is extra in summer time season than in winter.
• Further in extraordinarily bloodless climates water can be wasted because of faucets being usually stored open to keep away from freezing of pipes, which can also additionally bring about improved charge of consumption.

2.     Cost of Water:

• The fee at which water is furnished to the clients may additionally have an effect on the fee of call for of water. If the charges at which water is furnished are high, lesser amount of water can be ate up through the people, and vice versa. However, the overall commentary is that the intake of water reduces best barely because the fee is increased.

3.     Pressure with inside the Distribution System:

• The intake of water will increase with the boom with inside the distribution stress. This is because of boom in loss and waste of water at excessive stress. For example, a boom of stress from 196 kN/m2 (2 kg/cm2) to 294 kN/m2 (three kg/cm2) can also additionally result in a boom in intake of water through approximately 25 to 30 in step with cent.

4.     Economic Status of Consumers:

• The consumption charge of water is without delay based upon the economic recognition of the consumers. Rich and better beauty people normally consume more water due to their better well known of living. On the other hand, middle beauty people have not unusual place charge of consumption of water on the equal time because the horrific slum dwellers have a mile’s lower charge of water consumption.

Water system losses:

• Water loss from the pipe community, usually the bete noire of the operations engineer, has lengthy been a function of operations control, even in international locations with a well-advanced infrastructure and suitable running practices; but losses tackle a brand new size in growing international locations wherein terrible infrastructure, terrible sanitation, and intermittent materials can pose a severe fitness risk.
• Not all losses end result from terrible infrastructure and leaking pipes. "Appa-rent" losses from the community and immoderate use or misuse of water regularly end result from nearby customs, mixed with low tariff systems or insufficient metering policies.
• The creation of call for control and water conservation programmes along tasks to address leakage and enhance the pipe community can regularly lessen those losses and water overuse. Together, those programmes shape an approach for restoring a doubtlessly massive misplaced resource.

Factor affecting rate of demand:

For average Indian towns or cities, the rate of demand of water varies from 100 to 300 litres per head per day. The variation in the rate of demand of water is due to several factors which must be carefully studied and analyzed before fixing the rate of demand of water for a particular town or city.

1. Climatic Condition:

The requirement of water is more at places having hot and dry climate than at places having cold and humid climate. This is so because at places having hot and dry climate more water is required for bathing, washing of clothes, air coolers, air conditioning, lawn watering, gardening, etc.

2.     Cost of water:

The charge at which water is provided to the clients can also have an effect on the charge of call for of water. If the charges at which water is provided are high, lesser amount of water can be fed on through the people, and vice versa. However, the overall remark is that the intake of water reduces handiest barely because the fee is increased.

3.     Pressure in the Distribution System:

The intake of water will increase with the boom withinside the distribution strain. This is because of boom in loss and waste of water at excessive strain. For example, a boom of strain from 196 kN/m2 (2 kg/cm2) to 294 kN/m2 (three kg/cm2) can also additionally cause a boom in intake of water via way of means of approximately 25 to 30 according to cent.

4.     Economic Status of Consumers:

The intake price of water is immediately established upon the monetary reputation of the consumers. Rich and higher magnificence human beings commonly eat greater water because of their higher trendy of living. On the opposite hand center magnificence human beings have common price of intake of water at the same time as the terrible slum dwellers have miles decrease price of water intake.

5.     Number of Commercial Establishments and Industries:

In well-known the presence of industrial and different institutions and industries in a metropolis or town might boom the price of call for of water. The price of call for of water might in addition boom with the boom withinside the range of such institutions and industries. However, if the industries broaden their very own water deliver system, then there might not be a whole lot boom withinside the price of call for of water for the general public water deliver system.

6.      Method of Charging—Metered or Unmetered Water Supply System (or Policy of Metering):

The public water deliver device can be both metered or unmetered. In the case of metered water deliver, meters are outfitted at the top of the man or woman residence connections, which report the amount of water absolutely ate up through the purchasers. The purchasers are charged for the real amount of water ate up through them as recorded through the meters.

Population Forecasting:

• Population forecasting is described because the approach of figuring out the anticipated populace for a specific layout duration of a water deliver machine with the assist of the examine and evaluation of destiny activities and to be had records. The populace is a critical parameter this is decided for the layout of the water machine of a specific area.
• Water deliver structures are designed for a populace anticipated for a sure layout duration in preference to thinking of the prevailing populace of the area. There are numerous mathematical techniques that may be used to decide the populace for a layout duration.

Population Forecasting Methods

• The populace forecasting strategies require the values of gift and beyond populace data to go through the calculation. The nearby census data of a specific place offer the cost of gift and beyond populations. The classes of strategies used for populace forecasting are:

1. Short Term Methods
2. Long Term Methods

The short-term methods include:

1. Arithmetic Progression
2. Geometric Progression
3. IllerBankasi Method
4. Decreasing Rate of Growth method
5. Graphical Extension Method

The long-term methods include:

1. Comparative Method
2. Ratio and Correlation Method
3. Component Method
4. Logistic Method

Short Term Methods for Population Forecasting

The different short-term methods for forecasting population are:

1. Arithmetic Increase Method

• This method is applied to areas where it is found that the rate of increase of population with time is constant i.e. dP/dt = Constant;
• If, Pn = Population of an area after any time 't' or Population after 'n' decades, Po = Last known Population of that area; n = number of decades (10 years = 1 decade); X' = average increase in population.

Pn = Po + nX' (Eq.1)

Example:

Find population forecasting using arithmetic for the year 2021.

Solution:

Pn = P1+(ia+ic)

P2021= 22500+1(4833+750)

= 28033

Geometric Progression Method

• The method is used for the condition dP/dt = Kg. P. Where, Kg is called as the geometric constant, P is the population.

Kg = [(LnP'' -LnP')/ (t'' - t')] (Eq.2)

• Then the future population Pn is given by,

Ln Pn = Ln Po + K’g (tn - to); (Eq.3)

• K'g is Average of Kg which is equal to below relation.

Eq.4

3. IllerBankasi Method or Geometric Increase Method

• This method is employed in an area where the population is rapidly increasing. Here the future population Pn is given by,

Eq.5

• Here, r = Assumed growth rate in percentage, n is in decades and Po is the last known population of the city.
• The value of 'r' is calculated differently based on the data available.

1. If Initial Population P' and Final Population P'' are given, then

Eq.6

2. Arithmetic Increase method

r = (r1 + r2 + .... Rn)/n Eq.7

3. Geometric Method

  Eq.8

4. Decreasing Rate of Growth Method

• The method is applied to a city that owns a limiting saturation population. In this type, the rate of growth is a function of its population deficit. That means,

DP/dt = Kd(S-P) 

Where, P is the population, S is the saturation population and Kd is the constant.

Then, Kd and Kd average is given by,

Then, future population is given by,

5. Graphical Extension Method

• In this method, the population of the past few decades is plotted in the graph correctly following a proper scale. The obtained population curve is extended to obtain the future population. The extension of the curve is performed by a person who has proper experience and judgement.

Long Term Methods for Population Forecasting

• The long term methods for forecasting population are:

1. Comparative Method

In this method, population curve of different cities with similar population growth is studied. The different factors that are taken into consideration are:

• The likeness of Economic Base
• Proximity of geography
• Access to similar transportation systems

2. Ratio and Correlation Method

• The method works based on the concept that the ratio of the population of the city studied compared to a larger group continues to change in the future similar to the manner that has occurred in past years. The concept is explained in the figure below.

Fig 4: Ratio and Correlation method

is constant and

Population forecast for t he area under study

Population of the area under study at the last census

population of the region at the census

3. Component Method

• The population change is observed due to birth, death and migration. So, estimation of these factors helps to understand the increase or decrease of the population. During calculation, migration is estimated first followed by the estimation of births and deaths.

4. Logistic Method

• This method is also called as mathematical curve fitting. The method follows an assumption that the rate of growth at low population with a rate that is declining as the given city approach some value of limiting population.
• In order to proceed with this method, last three census is taken. If so the population is calculated by the formula,

S is the saturation population and m and c are constants

The Saturation population is calculated by the formula,

is the population at the last census, is the population one before the last census and is the population one before

  where

Key takeaways:

• The water required for unexpected fire accidents and undesirable situation with fire is already designed during the water demand planning system. 

1.9 Quality: physical, chemical, radioactivity and bacteriological characteristics, heavy metals. Standards as per IS 10500:2012

Quality:

• Man cannot survival without water but this water may be causes by bacteria if it is polluted by harmful agencies and used for drinking purpose. Pure water cannot be expected when the rain water flows as runoff if passes through the ground surface and gets collected in river lake and ponds on its way the water gets collected in river lake and ponds on its way the water get polluted by harmful salts, acids, minerals, pathogenic bacteria etc. hence odour test and disease causing microorganism.
• In early days, this types of surface water was consume by human being for drinking, bathing, washing, etc. in these days man did not have a technical knowledge for purifying pollutant water as a result man had to suffer water borne diseases like typhoid, cholera, etc.

There are several types of impurities they are as follows:

1. Physical Impurities:

• Turbidity
• Colour
• Test and odour
• Floating matters

2.     Chemical impurities:

• Acids
• Organic and inorganic compounds

Therefore, for removal of such type of bacterial impurities some test are to be conducted, and then we able to decide it is usable water or no

Radioactivity characteristics:

Some of the radionuclides which can be accountable for the herbal radioactivity in ingesting water come from radioactive elements, and their decay products, that have been included withinside the earth at its formation, and others are produced constantly with the aid of using cosmic ray bombardment.

Tritium is produced with the aid of using cosmic ray interactions with atmospheric oxygen and nitrogen. It is then oxidized to tritiated water, which combines into the hydrosphere. Tritium concentrations in water elements range from approximately 10 to twenty-five pCi/liter (Jacobs, 1968).

Bacteriological characteristics:

• Bacteriological fine is one of the crucial parameters of water potability. It is measured via way of means of the presence of a pollutant’s indicator of organisms, in particular, general germs and fecal coliforms (Escherichia coli). Total germs constitute the density of the bacterial populace in ingesting water.

Heavy metals:

• Heavy metals like Chromium (Cr), Cadmium (Cd), Mercury (Hg), Lead (Pb), Nickel (Ni), and Thallium (Tl) are probably risky in blended or elemental forms. Heavy metals are especially soluble withinside the aquatic environments and consequently they may be absorbed without problems through dwelling organisms.
• Previous research have detected heavy metals withinside the gills, liver, and muscle mass tissues of diverse species of fish in infected marine ecosystems2.
• Once the heavy metals input the meals chain, they'll emerge as collecting withinside the human body3. Since maximum heavy metals are broadly carried out in industries, publicity and infection of the employees and citizens close to such centers is possibly to occur. Heavy metals above allowable limits will regularly cause disadvantageous consequences in humans, different organisms and the surroundings at large

Standard limits that are used for daily use they are as follows:

Drinking Water Quality Standards

Water Quality Parameters and Bis Standards for Various Chemical and Biological Constituents

Water quality criteria

Ground water quality scenario in India

• Indian Sub-Continent is endowed with several geological formations from oldest Achaeans to Recent alluviums and characterized with the resource of the use of numerous climatic conditions in one-of-a-type additives of the USA of the us.
• The natural chemical content material cloth of ground water is prompted with the resource of the use of depth of the soils and sub-ground geological formations thru which ground water remains in contact.
• In general, extra part of the USA of the us, ground water is of exquisite quality and suitable for ingesting, agricultural or business features. Ground water in shallow aquifers is normally suitable for use for one-of-a-type features and is particularly of Calcium Bicarbonate and Mixed type. However, one-of-a-kind sorts of water are also available such as Sodium-Chloride water. The quality in deeper aquifers moreover varies from place to place and is normally determined suitable for now no longer unusual place uses.
• There is salinity problem withinside the coastal tracts and immoderate incidence of Fluoride, Arsenic, Iron and heavy metals and lots of others in isolated pockets have moreover been said. The distributions of various substances determined in ground water in one-of-a-type additives of the USA of the us is as follows.

Salinity

• Salinity in ground water can be appreciably categorized into types, i.e., Inland Salinity and Coastal salinity.

Inland Salinity

• Inland salinity in floor water is universal particularly withinside the arid and semi-arid areas of Rajasthan, Haryana, Punjab and Gujarat and to a lesser quantity in Uttar Pradesh, Delhi, Madhya Pradesh Maharashtra, Karnataka, Bihar and Tamil Nadu. About 2 lakhs sq.km location has been expected to be tormented by saline water of Electrical Conductivity in extra of 4000 μS/cm. There are numerous locations in Rajasthan and southern Haryana wherein EC values of floor water is extra than ten thousand μS /cm making water nonportable.
• Inland salinity is likewise brought on because of exercise of floor water irrigation without attention of floor water status. The sluggish upward thrust of floor water tiers with time has ended in water logging and heavy evaporation in semi-arid areas cause salinity trouble in command regions. As consistent with current evaluation approximately 2. Forty-six m ha of the location below floor water irrigation initiatives is water logged or threatened with the aid of using water logging.

Coastal Salinity

• Coastal regions constitute zones wherein land and sea meet and incorporates range of complicated environments together with deltas, estuaries, bays, marshes, dunes and beaches. Coastal aquifers have barriers in touch with seawater and are continually below dynamic equilibrium with it. Withdrawal of sparkling floor water from those aquifers may also end result in in equilibrium ensuing in intrusion of saline water in coastal aquifers.
• The Indian subcontinent has a dynamic coast line of approximately 7500 km length. It stretches from Rann of Kutch in Gujarat to Konkan and Malabar coast to Kanyakumari with inside the south to northwards alongside the Coromandal coast to Sunder bans in West Bengal.
• The western coast is characterized with the aid of using extensive continental shelf and is marked with the aid of using backwaters and dust flats whilst the jap coast has a slim continental shelf and is characterized with the aid of using deltaic and estuarine land forms. Ground water in coastal regions happens below unconfined to confined situations in an extensive variety of unconsolidated and consolidated formations.

Key Takeaways:

Population forecasting, Fire demand, Arithmetic incremental increase method, water system losses, factors affecting fire demand

References:

1. Environmental Engineering, Peavy and Rowe, McGraw Hill Publication
2. Optimal Design of Water Distribution Networks, P.R. Bhave, Narosa Publishing House
3. Rain Water Harvesting: Making water Every Bodys business, vcentre for science and Environment
4. Environmental Remote sensing from Regional to global Scales, Ed. Giles Foody, Wiley
5. Water supply Engineering, Harold FatonBabbit& James Joseph Doland, Tata Mcgraw Hill
6. Environmental Engineering Laboratory Manual and Dr. N. Kumarswamy. NEERI, Nagpur