JNTU B.Tech III ENVIRONMENTAL ENGINEERING Previous Question Paper (November/December - 2020 - R16)

To estimate the population for the years 2020 and 2040, the Incremental Increase Method is the most appropriate approach as it accounts for the changing rate of growth.

Average increase (x̄) = 23,500 / 3 = 7,833.33. Average incremental increase (ȳ) = 6,500 / 2 = 3,250.

The formula for future population is P_n = P_o + n(x̄) + [n(n+1)/2]ȳ, where P_o is the last known population (32,500 in 1990) and n is the number of decades.

For 2020 (n = 3 decades):
P₂₀₂₀ = 32,500 + 3(7,833.33) + [3(4)/2](3,250)
P₂₀₂₀ = 32,500 + 23,500 + 19,500 = 75,500

For 2040 (n = 5 decades):
P₂₀₄₀ = 32,500 + 5(7,833.33) + [5(6)/2](3,250)
P₂₀₄₀ = 32,500 + 39,166.65 + 48,750 = 120,416.65

The probable population is 75,500 in 2020 and approximately 120,417 in 2040.

An intake structure is a hydraulic facility designed to withdraw water from a surface source, such as a river, lake, or reservoir, and convey it to the water treatment plant. Its primary functions are to ensure a continuous supply of water, protect the conveyance system from debris and ice, and allow for the selection of water from different depths to optimize quality.

A reservoir intake is typically constructed in a dam or near the embankment of a reservoir. Because water levels in reservoirs fluctuate significantly due to seasonal demand and rainfall, these intakes are designed to draw water at varying elevations.

Key components and operation of a reservoir intake include:

• Intake Tower: A vertical masonry or concrete structure located in the reservoir, equipped with multiple intake ports (gates) at different levels to allow withdrawal of water from the best available quality zone.
• Conduit: A pipe or tunnel that transports the water from the intake tower through or under the dam to the treatment plant.
• Trash Rack: A screen placed at the entrance of the intake ports to prevent floating debris, fish, or large objects from entering the system.
• Operating Mechanism: Valves or sluice gates located within the tower that are operated from a bridge or the top of the tower to control the flow and select the intake level.

In a typical sketch, the reservoir intake is represented as a tower structure situated within the reservoir basin. The diagram would show the water surface level, the intake ports at various heights along the tower face, the trash racks covering these ports, the internal piping system, and the conduit leading through the dam body to the downstream side. The tower is usually connected to the dam crest by a footbridge to provide access for maintenance and operation of the control valves.