JNTU B.Tech III ENVIRONMENTAL ENGINEERING Previous Question Paper (January/February - 2021 - R16)

The per capita demand for water supply is the average amount of water used by one person in a day, calculated by dividing the total annual water consumption by the population and 365 days. Several factors influence this demand:

• Size of the city: Larger cities often have higher per capita demand due to extensive commercial, industrial, and public water requirements.
• Standard of living: Higher economic status and lifestyle standards lead to increased usage of modern appliances like dishwashers, washing machines, and showers.
• Industrial and commercial activities: The presence of water-intensive industries or large commercial hubs significantly increases the total demand.
• Climatic conditions: In hot and dry climates, water consumption for gardening, cooling, and personal hygiene is significantly higher than in cold regions.
• Quality of water supply: If the supplied water is of high quality and pressure, consumption tends to be higher. Poor pressure or quality may lead to lower usage or reliance on alternative sources.
• System pressure: High pressure in the distribution system increases the volume of water drawn and also exacerbates leakage losses.
• Metering and pricing: Metered connections and progressive water tariffs generally encourage water conservation, thereby reducing per capita demand.
• System efficiency: The extent of leakage, wastage, and unauthorized connections in the distribution network directly affects the total per capita supply required.

The Geometric Increase Method is a population forecasting technique based on the assumption that the percentage growth rate of a population remains constant over time. It is particularly suitable for young, rapidly growing cities where industrialization and economic expansion drive significant migration and development.

The formula for the population after n decades is:

Where:

• P_n: Future population after n decades.
• P_0: Last known census population.
• r: Assumed geometric growth rate (percentage).
• n: Number of decades.

The significance of this method lies in its ability to account for the compounding effect of population growth. Unlike the arithmetic method, which assumes a constant linear increase, the geometric method reflects the reality that population growth is often proportional to the existing population size, making it a more accurate tool for predicting infrastructure requirements in developing urban centers.