21) The porosity (v) and the hydraulic conductivity (k) of four soil formations is shown below. Assume that all four formations have approximately the same dimensions, are located at approximately the same depth and are completely saturated. At which formation would you choose to drill in order to pump water.
- -n=31, k=0.1 m/day
- -n=18, k=800 m/day
- -n=19, k=1 m/day
- -n=39, k=0.05 m/day
22) You are responsible for assessing whether a saturated soil formation is potentially exploitable. Which of the following characteristics of the formation are most useful for this preliminary evaluation?
- Area, layer thickness, porosity (n)
- Area, layer thickness, hydraulic conductivity (K)
- Area, layer thickness, specific yield (Sy)
- Layer thickness, hydraulic conductivity (K), specific yield (Sy)
23) A plastic tank has a volume of 1 m3 and it is filled with sand. We start adding water to the tank until the voids between sand particles are filled with water and the water reaches the top level of the tank (just before it overflows). The total water added was 400 L. Then we opened the tank drain valve until the sand was completely drained. The water that escaped through the faucet was 200 L. What is the specific yield of that soil material?
- 40%
- 20%
- 12%
- Δεν μπορεί να υπολογιστεί με τα δεδομένα που δίνονται.
24) The runoff of a river ends up in a reservoir with a capacity of 20 MCM. The reservoir is used exclusively for the water supply of a city. Which of the following is WRONG in relation to the main statistical difference between the average monthly Qin inflow to the reservoir and the average monthly Qout outflow to the city.
- The standard deviation of the mean monthly Qin is greater than the standard deviation of the mean monthly Qout
- The standard deviation of the mean monthly Qin is smaller than the standard deviation of the mean monthly Qout
- The mean monthly Qout is more predictable than the mean monthly Qin
25) The photo depicts a coastal area. The area with shades of yellow and red is the sea. Based on the legend, what does the color red indicate?
- An area with lower salinity due to the escape of fresh water from an inland aquifer to the sea.
- An area with lower temperature due to the escape of fresh water from an inland aquifer to the sea.
- An area with higher temperature due to the escape of fresh water from an inland aquifer to the sea.
26) With regards to water well drilling, which of the following is WRONG?
- The perforated filter (screen) in combination with the layer of gravel retains the soil material so that cavitation is prevented and the well is not filled with soil particles from the aquifer.
- Grouting cement protects against possible contamination.
- The shield holds the walls of the well and protects it from possible contamination. Shielding the drill is not always required.
- Drilling by hand can only be done for shallow depths and drilling diameters less than 30 cm
27) In the context of water resources management in Cyprus, the preparation of annual water scenarios for the management of the Public Water Development Works is done by:
- The Municipalities and the final approval is given by the Department of Water Development.
- The Department of Water Development and the final approval is given to the President of the Republic.
- The Department of Water Development and the final approval is given by the Council of Ministers.
- The Irrigation Committees and the final approval is given by the Department of Water Development.
28) Between River 1 and River 2 in the figure below, there is a flow through a permeable land formation which is uneven. Roughly speaking, we can assume that the formation is divided into three areas: low, medium and high hydraulic conductivity. Which of the following is correct?
- Κ3>Κ2>Κ1
- Κ1< Κ3< Κ2
- Κ1>Κ2>Κ3
- Κ1>Κ2<Κ3
29) The following statement is CORRECT OF INCORRET
In areas where there are dams with large reservoirs, it does not make sense to invest in large projects for exploiting any upstream aquifers since most of the potential of those aquifers can be captured at the reservoir.
30) Statement: “The degradation of the water level at unconfined aquifer as well as the extraction of significant amounts of water from confined aquifers can cause soil settlement. This is because as the hydraulic pressure decreases and the weight of overburden soil is balanced to a greater extent by forces developed between the soil particles”
- The above statement is incorrect. Water pumping cannot cause ground settlement.
- The above statement is correct
- I agree that water pumping from an aquifer can cause settlement but not due to the reasons mentioned in the above statement.