Yield of a Confined Aquifer

Q. A well of diameter $20\text{cm}$ fully penetrates a confined aquifer. After a long period of pumping at a rate of $2720\text{L/min}$, the observations of drawdown taken at $10\text{m}$ and $100\text{m}$ distances from the centre of the well are found to be $3\text{m}$ and $0.5\text{m}$ respectively. The transmissivity of the aquifer is ________.

1. $676{\text{m}}^2/\text{day}$
2. $576{\text{m}}^2/\text{day}$
3. $526{\text{m}}^2/\text{day}$
4. $249{\text{m}}^2/\text{day}$

Q. A well diameter 30 cm fully penetrated a confined aquifer of 25 m thick. After a long period of pumping at a steady state, the observations drawdown taken at 25 m and 75 meters distances from the centre of the main well are found to be 5 m and 1.5 m respectively. If the coefficient of permeability of the aquifer is 12 m/day, the steady state discharge from the main well would be ____ liter/min.

1. 4170.25

Q. A tube well of 30 cm diameter penetrates fully into an artesian aquifer. The strainer length is 15 m. The yield from the well under a drawdown of 3 m through the aquifer consisting of sand of effective size of 0.2 mm and coefficient of permeability of 50 m/day, with radius of drawdown of 150 m, is nearly

1. $240l/s$
2. $120l/s$
3. $24l/s$
4. $12l/s$

Q. A fully penetrating confined aquifer is pumped at a constant rate of $Q{m}^3/sec$. The drawdowns at an observation well at a distance r from pumping well are in the ratio of 3 : 4 after one and two hours of pumping respectively. The storage coefficient is s, the transmissibility of the aquifer (in $m^2/sec$) is :

1. $32r^{2}S/9$
2. $r^{2}S/9$
3. $2r^{2}S/2025$
4. None of above

Q. An aquifer confined at top and bottom by impermeable layers is stratified into three layers as follows:
$\begin{array}{ccc}\text{Layer}& \text{Thickness}& \text{Permeability}\\ & \text{(m)}& \text{(m/day)}\\ \text{Top layer}& 4& 30\\ \text{Middle layer}& 2& 10\\ \text{Bottom layer}& 6& 20\end{array}$

The transmissivity (${\text{m}}^2$/day) of the aquifer is

1. 260
2. 227
3. 80
4. 23

Q. For steady flow to a fully penetrating well in a confined aquifer, the drawdowns at radial distances of $r_1$ and $r_2$ from the well have been measured as $s_1$ and $s_2$ respectively, for a pumping rate of $Q$. The transmissivity of the aquifer is equal to

1. $\frac{Q}{2\pi }\left[\frac{ln\frac{r_2}{r_1}}{s_1-s_2}\right]$
2. $\frac{Q}{2\pi }\left[\frac{ln(r_2-r_1)}{s_1-s_2}\right]$
3. $\frac{Q}{2\pi }ln\left[\frac{\frac{r_2}{r_1}}{\frac{s_2}{s_1}}\right]$
4. $2\pi Q\frac{r_2-r_1}{ln\left(\frac{s_2}{s_1}\right)}$

Q. The surface joining the static levels in several non-pumping wells penetrating a continuous confined aquifer represents

1. Water table surface
2. Capillary fringe
3. Piezometric surface of the aquifer
4. Physical top surface of the aquifer

Q. Match List-I (Equation) with List-II (Applicability or principle of equation) and select the correct answer using the codes given below the lists:

List- I
A. Thiem's equation
B. Dupit's assumption
C. Bernoulli's equation
D. Continuity equation

List - II
1. is based on energy conservation principle
2. is based on mass conservation principle
3. is applicable to steady flow towards a well in a confined aquifer.
4. is applicable to steady flow in an unconfined aquifer.

1. A-4, B-3, C-2, D-1
2. A-3, B-4, C-2, D-1
3. A-4, B-3, C-1, D-2
4. A-3, B-4, C-1, D-2

Q. A tube well of 30 cm diameter penetrates fully into an artesian aquifer. The strainer length is 15 m. The yield from the well under a drawdown of 3 m through the aquifer consisting of sand of effective size of 0.2 mm and coefficient of permeability of 50 m/day, with radius of drawdown of 150 m, is nearly

1. $240l/s$
2. $120l/s$
3. $24l/s$
4. $12l/s$