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University of Zambia School of Engineering Department of Civil and Environmental CEE 4311 ASSIGNMENT # 5 Question 1 The static level of water table in an unconfined aquifer was 30 m above the underlying impermeable stratum. A 150 mm diameter well, penetrating the aquifer to its full depth, was pumped at the rate of 20 litres per second. After several weeks of pumping, the drawdown in observation wells 20 m and 50 m from the well were 3.5 m and 2 m respectively, and the observed drawdowns were increasing very slowly. a) Assuming equilibrium conditions, estimate the hydraulic conductivity and transmissivity of the aquifer. b) Estimate the drawdown just outside the pumped well. c) What will be the yield of a 300 mm diameter well which will produce the same drawdowns just outside the well and at the 50 m distance observation well in (2)? What would be the drawdown at a nearer observation well? Question 2 A well penetrates an unconfined aquifer having a saturated depth of 100 m. The discharge is 250 litres per minute at 12 m drawdown. Assuming equilibrium flow conditions and a homogeneous aquifer, estimate the discharge at 18 m drawdown. The distance from the well where the drawdown influence are not appreciable may be taken to be equal for both cases. Question 3 Gravity well is 50 cm in diameter. The depth of water in the well is 30 meters before the start of pumping. Upon pumping at a rate of 2,100 liters per minute, Water level into a well located about 10 meters away fell by 3 meters, and in another well 20 meters away it reached 1.5 meters. Find: the zero draw down, permeability coefficient, and the drawdown in the well. Date: 20 th June 2022 Dr J. Kabika - Lecturer of Hydrology

          University of Zambia
School of Engineering
Department of Civil and Environmental
CEE 4311 ASSIGNMENT # 5

Question 1

The static level of water table in an unconfined aquifer was 30 m above the underlying impermeable stratum. A 150 mm diameter well, penetrating the aquifer to its full depth, was pumped at the rate of 20 litres per second. After several weeks of pumping, the drawdown in observation wells 20 m and 50 m from the well were 3.5 m and 2 m respectively, and the observed drawdowns were increasing very slowly.
a) Assuming equilibrium conditions, estimate the hydraulic conductivity and transmissivity of the aquifer.
b) Estimate the drawdown just outside the pumped well.
c) What will be the yield of a 300 mm diameter well which will produce the same drawdowns just outside the well and at the 50 m distance observation well in (2)? What would be the drawdown at a nearer observation well?

Question 2
A well penetrates an unconfined aquifer having a saturated depth of 100 m. The discharge is 250 litres per minute at 12 m drawdown. Assuming equilibrium flow conditions and a homogeneous aquifer, estimate the discharge at 18 m drawdown. The distance from the well where the drawdown influence are not appreciable may be taken to be equal for both cases.

Question 3

Gravity well is 50 cm in diameter. The depth of water in the well is 30 meters before the start of pumping. Upon pumping at a rate of 2,100 liters per minute, Water level into a well located about 10 meters away fell by 3 meters, and in another well 20 meters away it reached 1.5 meters. Find: the zero draw down, permeability coefficient, and the drawdown in the well.

Date: 20 th June 2022
Dr J. Kabika - Lecturer of Hydrology

University of Zambia
School of Engineering
Department of Civil and Environmental
CEE 4311 ASSIGNMENT # 5

Question 1

The static level of water table in an unconfined aquifer was 30 m above the underlying impermeable stratum. A 150 mm diameter well, penetrating the aquifer to its full depth, was pumped at the rate of 20 litres per second. After several weeks of pumping, the drawdown in observation wells 20 m and 50 m from the well were 3.5 m and 2 m respectively, and the observed drawdowns were increasing very slowly.
a) Assuming equilibrium conditions, estimate the hydraulic conductivity and transmissivity of the aquifer.
b) Estimate the drawdown just outside the pumped well.
c) What will be the yield of a 300 mm diameter well which will produce the same drawdowns just outside the well and at the 50 m distance observation well in (2)? What would be the drawdown at a nearer observation well?

Question 2
A well penetrates an unconfined aquifer having a saturated depth of 100 m. The discharge is 250 litres per minute at 12 m drawdown. Assuming equilibrium flow conditions and a homogeneous aquifer, estimate the discharge at 18 m drawdown. The distance from the well where the drawdown influence are not appreciable may be taken to be equal for both cases.

Question 3

Gravity well is 50 cm in diameter. The depth of water in the well is 30 meters before the start of pumping. Upon pumping at a rate of 2,100 liters per minute, Water level into a well located about 10 meters away fell by 3 meters, and in another well 20 meters away it reached 1.5 meters. Find: the zero draw down, permeability coefficient, and the drawdown in the well.

Date: 20 th June 2022
Dr J. Kabika - Lecturer of Hydrology

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