Properties of Aquifer

Q. An unconfined aquifer of porosity 30% permeability 35m/day and specific yield of 0.20 has an area of $100{\text{km}}^2$. If the water table falls by 0.25 m during a drought, the volume of water lost from storage, in million cubic metres, is

1. 2.0
2. 5.0
3. 1.0
4. 4.0

Q. Volume of water given by unit area of confined aquifer when Piezometric surface falls by unity is called.

1. Specific yield
2. Specific storage
3. Specific retention
4. Storativity

Q. When 3.5 million ${\text{m}}^3$ of water is pumped out from an unconfined aquifer of $6.3{\text{km}}^2$ areal extent, the water table was observed to go down by 2.5 m. The specific yield of the aquifer is best approximated as

1. 32%
2. 28%
3. 25%
4. 22%

Q. Water table of an aquifer drops by $100\text{cm}$ over an area of $1000{\text{km}}^2$. The porosity and specific retention of the aquifer material are $25\%$and $5\%$ respectively. The amount of water drained out (expressed in $k{m}^3$) from the area is _____

1. 0.2

Q. A groundwater basin consists of $10k{m}^2$ area of plains. The maximum groundwater table fluctuation has been observed to be 1.5 m. Consider specific yield of the basin as 10%. What is the available groundwater storage in million cubic metres?

1. 1.0
2. 1.5
3. 2.5
4. 2.0

Q. An unconfined aquifer of porosity 35%, permeability 40 m/day and specific yield of 0.15 has an area of $100{\text{km}}^2$. If the water table falls uniformly throughout the aquifer area by 0.2 m during a drought, the volume of water lost from storage is ________.

1. $1.5{\text{Mm}}^3$
2. $3.0{\text{Mm}}^3$
3. $7.0{\text{Mm}}^3$
4. $8.0{\text{Mm}}^3$

Q. What would be the volume of water stored in a saturated column with a porosity of 0.35 with a cross-sectional area of $1{\text{m}}^2$ and depth of 3 m ?

1. $2.0{\text{m}}^3$
2. $0.105{\text{m}}^3$
3. $1.05{\text{m}}^3$
4. $3.0{\text{m}}^3$

Q. Water table drops by 4 m in a field having 180 ha area. If the porosity of soil in the field is 0.25 and the specific retention is 0.15, then the change in volume of storage (in $M{m}^3)$ in the aquifer is:

1. 0.72
2. 1.80
3. 7.20
4. 18.0