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# GATE CE 2022: Environmental Engineering Quiz #2

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Question 1

The ground water is pumped through an aquifer having an area of 1.80 sq km which has a porosity of 0.65.Specific retention of the medium is 0.15. Find the change in the ground water storage (in Mm3) when the water table drops from 10 m to 35 m.

Question 2

Two wells are fully penetrating in a confined aquifer at two different locations. The ratio of permeability and thickness of the two wells in aquifer are 5 and 10, respectively. The transmissivity ratio (nearest integer) of these two wells is ________.

Question 3

An infiltration gallery is placed at a depth of 5 m from the ground water table, The coefficient of permeability of soil of the aquifer is 100m/day. The drawdown of the gallery should not exceed 3 m. Find the length of the gallery if 200 m3 of water is required to be obtained per day. Assume the radius of influence to be 80 m.

Question 4

A fully penetrating artesian well is discharging at a rate of 25 l/sec. storage coefficient and transmissibility of aquifer us 4.5 × 10–4 & 0.15 m2/min. Find drawdown at distance 5 m after two hour

Question 5

During a recuperative test, the water is pumped out 2.8 m initially and allowed to recuperate. It was observed that the water level rises by 1.45m in 80 minutes. If the diameter of the well is 3.45m, determine by what amount the diameter need to be increased to get a yield of 5 litre per sec under a depression head of 1.65m.

Question 6

A tube-well of 20 cm diameter fully penetrates a horizontal, homogeneous and isotropic confined aquifer of infinite horizontal extent. The aquifer is of 30 m uniform thickness. A steady pumping at the rate of 40 litres/s from the well for a long time results in a steady drawdown of 4 m at the well face. The subsurface flow to the well due to pumping is steady, horizontal and Darcian and the radius of influence of the well is 245 m. The hydraulic conductivity of the aquifer (in m/day, round off to integer) is_____.
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