Source Of Water Supply Distribution System And Well Hydraulics Practice Questions

A $30 \mathrm{~cm}$ diameter well fully penetrates an unconfined aquifer of saturated thickness 20 $\mathrm{m}$ with hydraulic conductivity of $10 \mathrm{~m}$ day. Under the steady pumping rate for a long time, the drawdowns in two observation wells located at $10 \mathrm{~m}$ and $100 \mathrm{~m}$ from the pumping well are $5 \mathrm{~m}$ and $1 \mathrm{~m}$ . respectively. The corresponding pumping rate (in $\mathrm{m}^{3}$ day) from the well is (rounded off to 2 decimal places).

The concentration $s(x,t)$ of pollutants in a one-dimensional reservoir at position $x$ and time $t$ satisfies the diffusion equation $\frac{\partial s(x,t)}{\partial t}=D\frac{\partial^2 s(x,t)}{\partial x^2}$ on the domain $0 \leq x \leq L$ , where $D$ is the diffusion coefficient of the pollutants. The initial condition $s(x, 0)$ is defined by the step-function shown in the figure. The boundary conditions of the problem are given by $\frac{\partial s(x,t)}{\partial x}=0$ at the boundary points $x = 0$ and $x = L$ at all times. Consider $D = 0. 1 m^2/s, s_0 = 5 \mu mol/m$ , and $L = 10 m$ . The steady-state concentration $\tilde{S}\left ( \frac{L}{2} \right )=S\left ( \frac{L}{2},\infty \right )$ , at the center $x=\frac{L}{2}$ of the reservoir (in $\mu$ mol/m) is ___________. (in integer)

A lake has a maximum depth of 60 m. If the mean atmospheric pressure in the lake region is 91 kPa and the unit weight of the lake water is $9790 \mathrm{~N} / \mathrm{m}^{3}$ , the absolute pressure (in kPa,round off to two decimal places) at the maximum depth of the lake is ___________

Dupuit's assumptions are valid for

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

A tracer takes 100 days to travel from Well-1 to Well-2 which are 100 m apart. The elevation of water surface in Well-2 is 3m below that in Well-1. Assuming porosity equal to 15%, the coefficient of permeability (expressed in m/day) is

The relationship between porosity ( $\eta$ ), specific yield ( $S_{y}$ ) and specific retention ( $S_{r}$ ) of an unconfined aquifer is:

In an aquifer extending over 150 hectare, the water table was 20m below ground level. Over a period of time the water table dropped to 23m below the ground level. If the porosity of aquifer is 0.40 and the specific retention is 0.15, what is the change in ground water storage of the aquifer?

A well of diameter 20 cm fully penetrates a confined aquifer. After a long period of pumping at rate of 2720 litres per minute, the observations of drawdown taken at 10 m and 100 m distances from the centre of the well are found to be 3m and 0.5m respectively. The transmissivity of the aquifer is

The relationship among specific yield ( $S_{y}$ ), specific retention ( $S_{r}$ ) and porosity ( $\eta$ ) of an aquifer is

A volume of $3.0 \times 10^{6} m^{3}$ of groundwater was pumped form an unconfined aquifer uniformly from an area of 5 $km^{2}$ . The pumping lowered the water table form initial level of 102 m to 99 m. The specific yield of the aquifer is

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

Match the following

Two observation wells penetrated into a confined aquifer and located 1.5 km apart in the direction of flow, indicate head of 45 m and 20 m. If the coefficient of permeability of the aquifer is 30 m/day and porosity is 0.25, the time of travel of an inert tracer from one well to another is

Water is pumped from a well tapping an unconfined aquifer at a certain discharge rate and the steady state draw down (X) in an observation well is monitored. Subsequently, the pumping discharge is doubled and the steady state draw down in the same observation well is found to be more than double (i.e., more than 2X). This disproportionate draw down is caused by

When there is an increase in the atmospheric pressure, the water level in a well penetrating in a confined aquifer