A 45 cm diametre well penetrates an unconfined aquifer of 30 m thick. Under the steady pumping rate for a long time, the drawdown's at two observation wells 10 m and 20 m from the pumping well are 5 m and 3.5 m respectively. What will be the discharge (cumec), if the permeability of the aquifer is given as 20 m/day?
10 m thick confined aquifer gives the steady state discharge of 0.03 m³/s through the well of 50 cm radius. Due to pumping the height of water in the well is dropped from 15 m to 10 m and the radius of influence is obtained as 500 m. What is the coefficient of permeability (mm/s)?
K = Q ln(R/Rw)/(2 pi D Sw) = 6.59x10^-4 m/s = 0.66 mm/s.
Question 7Hard
In the falling head permeability test, in the duration of 3 hours the initial head of 1000 mm is dropped to 350 mm. The diameter of the stand pipe is 0.5 cm. The length and diameter of the soil specimen are 20 cm and 10 cm respectively. What is the coefficient of permeability (mm/s) of the soil?
n = e/(1+e) = 1/3; seepage velocity Vs = V/n = 18x10^-7 m/s.
Question 9Hard
Falling head permeability test is carried out on a soil specimen having cross-sectional area of 60 sq. cm. and height of 15 cm. The water level in the stand pipe of diametre of 0.5 cm drops from 100 cm to 40 cm in half an hour. What is the coefficient of permeability (cm/s)?