Question

Consider a sand aquifer that is confined. The aquifer is 5.5 m thick, has a specific storage of 1.2×10−⁴ m−¹ , and a specific yield of 0.12. Between 2000 and 202090,000 m³ of water were pumped from the aquifer for agricultural irrigation. Calculate the decline in head over a 1.5 km² area of the aquifer as a result of this 90,000 m³ withdrawal.

Answer 1

The decline in head over a 1.5 km² area of the aquifer as a result of the 90,000 m³ withdrawal is 660,000,000 meters.

Step-by-step explanation:

To calculate the decline in head over a 1.5 km² area of the aquifer as a result of the 90,000 m³ withdrawal, we need to use the specific storage and specific yield values. First, we need to calculate the change in volume of the aquifer due to the withdrawal. This can be done by multiplying the specific yield by the thickness of the aquifer and the area of the withdrawal: 0.12 x 5.5 m x 1.5 km² = 0.99 km³. Next, we convert the change in volume from cubic kilometers to cubic meters: 0.99 km³ x 1,000,000,000 m³/km³ = 990,000,000 m³.

Finally, we can calculate the decline in head by dividing the change in volume by the area of the withdrawal: 990,000,000 m³ / 1.5 km² = 660,000,000 m. Therefore, the decline in head over a 1.5 km² area of the aquifer as a result of the 90,000 m³ withdrawal is 660,000,000 meters.