Question

An unconfined aquifer has an initial thickness of 15.80 m. The initial water table is horizontal and located 4.7 m below the ground surface. A 15-cm diameter well is driven to the bottom of the aquifer and pumped at 3000 Lpm until steady state conditions are achieved. At this time the drawdown at the well is 4.35 m and the drawdown in an observation well located 850 m away is 0.12 m.

(a) Make a sketch that defines the problem. The sketch should be neat and should fit the full width of a sheet of paper. It should be scaled appropriately; the horizontal and vertical scales can differ. Label the ground surface, the aquifer bottom, the initial and final water tables, and dimension lines that indicate the following six numbers from the problem statement: 15.80 m, 4.7 m, 15 cm, 4.35 m, 850 m, 0.12 m.

(b) Estimate the hydraulic conductivity. Report your answer in m/s.

(c) The pumping rate is increased to 3500 Lpm and pumping continues until a new steady state is achieved. Determine the drawdown in the pumping well if the drawdown at 850 m increases to 0.13 m.

Answer 1

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