Water Demand Notes | Study Environmental Engineering - Civil Engineering (CE)

Civil Engineering (CE): Water Demand Notes | Study Environmental Engineering - Civil Engineering (CE)

The document Water Demand Notes | Study Environmental Engineering - Civil Engineering (CE) is a part of the Civil Engineering (CE) Course Environmental Engineering.
All you need of Civil Engineering (CE) at this link: Civil Engineering (CE)

Fire Demand

Rate of fire demand is sometimes treated as a function of population and is worked out on the basis of empirical formulas:

  1. As per GO Fire Demand
    = 100(P)1/2
  2. Kuichling’s Formula
    Water Demand Notes | Study Environmental Engineering - Civil Engineering (CE)
    Where Q = Amount of water required in liters/minute.
    P = Population in thousand.
  3. Freeman Formula
    Water Demand Notes | Study Environmental Engineering - Civil Engineering (CE)
  4. National Board of Fire Under Writers Formula
    (i) For a central congested high valued city
    (a) Where population < 200000
    Water Demand Notes | Study Environmental Engineering - Civil Engineering (CE)
    (b) where population > 200000
    Q = 54600 lit/minute for first fire
    and Q = 9100 to 36,400 lit/minute for a second fire.
    (ii) For a residential city.
    (a) Small or low building,
    Q = 2,200 lit/minutes.
    (b) Larger or higher buildings,
    Q = 4500 lit/minute.
    (c) High value residences, apartments, tenements
    Q = 7650 to 13,500 lit/minute.
    (d) Three storeyed buildings in density built-up sections,
    Q = 27000 lit/minute.
  5. Buston’s Formula
    Water Demand Notes | Study Environmental Engineering - Civil Engineering (CE)
    The probability of occurrence of a fire, which, in turn, depends upon the type of the city served, has been taken into consideration in developing a above formula on the basis of actual water consumption in fire fighting for Jabalpur city of India. The formula is given as
    Water Demand Notes | Study Environmental Engineering - Civil Engineering (CE)
    Where,
    R = Recurrence interval of fire i.e., period of occurrence of fire in years, which will be different for residential, commercial and industrial cities.

Per Capita Demand (q)
Water Demand Notes | Study Environmental Engineering - Civil Engineering (CE)

Assessment of Normal Variation
Water Demand Notes | Study Environmental Engineering - Civil Engineering (CE)

Population forecasting Methods
  1. Arithmetic increase method
    Water Demand Notes | Study Environmental Engineering - Civil Engineering (CE)
    Where,
    Prospective or forecasted population after n decades from the present (i.e., last known census)
    Population at present (i.e., last known census)
    n = Number of decades between now & future.
    Average (arithmetic mean) of population increases in the known decades.
  2. Geometric Increase Method
    Water Demand Notes | Study Environmental Engineering - Civil Engineering (CE)
    where,
    Po = Initial population.
    Pn = Future population after ‘n’ decades.
    r = Assumed growth rate (%).
    Water Demand Notes | Study Environmental Engineering - Civil Engineering (CE)
    where,
    P2 = Final known population
    P1 = Initial known population
    t = Number of decades (period) between P1 and P2.
    Water Demand Notes | Study Environmental Engineering - Civil Engineering (CE)
  3. Incremental Increases Method
    Water Demand Notes | Study Environmental Engineering - Civil Engineering (CE)
    Where,
    Water Demand Notes | Study Environmental Engineering - Civil Engineering (CE) Average increase of population of known decades
    Water Demand Notes | Study Environmental Engineering - Civil Engineering (CE) Average of incremental increases of the known decades.
  4. Decreasing rate of growth method
    Since the rate of increase in the population goes on reducing, as the cities reach towards saturation, a method which makes use of the decrease in the percentage increase, in many times used, and gives quite rational results. In this method, the average decrease in the percentage increase is worked out, and is then subtracted from the latest percentage increase for each successive decade. This method is, however, applicable only in cases, where the rate of growth shows a downward trend.
  5. Logistic Curve Method
    (a)
    Water Demand Notes | Study Environmental Engineering - Civil Engineering (CE)
    Where,
    Po = Population of the start point.
    Ps = Saturation population
    P = Population at any time t from the origin.
    k = Constant.
    Water Demand Notes | Study Environmental Engineering - Civil Engineering (CE)

The document Water Demand Notes | Study Environmental Engineering - Civil Engineering (CE) is a part of the Civil Engineering (CE) Course Environmental Engineering.
All you need of Civil Engineering (CE) at this link: Civil Engineering (CE)
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