31) Which of the following statement is INCORRECT with regard to groundwater over-pumping:
- The lowering the water level at unconfined aquifers or the lowering of the pressure at confined aquifers, increases the pumping costs in a linear ratio.
- Groundwater over-pumping causes soil subsidence.
- Groundwater over-pumping can lead to damage to the perforated filter and the gravel layer around the filter resulting in the failure of a water well.
- Over-pumping and consequent lower of the water horizon of the aquifer can cause complete depletion in adjacent shallow boreholes.
- Over-pumping of water in coastal areas causes seawater to penetrate.
32) The total freshwater on the Earth consists of groundwater (98.5%) and surface water (1.5%). Nevertheless, most of the water needs are currently met by surface water because:
- The use of surface water is less costly.
- The rate of replenishment of surface water is faster than the rate of replenishment of groundwater.
- The collecting and storage of surface water is technically easier.
- All of the above.
33) Suppose two similar aquifers (same dimensions, same soil material) with the only difference that the one is confined and the other is unconfined. The storage capacity of the unconfined aquifer compared to that of the unconfined is:
- Equal in both cases, because the storage depends only on the material and size of the aquifers.
- It is smaller because the water in the confined aquifers is under pressure
- It is much larger, because the contribution of gravitational drainage in the porous medium is much greater than the compressibility of the water and the soil particles.
(34) In the flat part of a river basin there is an large alluvial aquifer. If the groundwater is extensively exploited, then the surface water resources of the basin are expected to:
- Remain unchanged
- Increase.
- Decrease.
35) When considering a time period of one month, in which of the following cases can we calculate the change in storage at a higher accuracy using the water balance equation:
- For the case of drainage basin
- For the case of an aquifer
- For the case of dam reservoir
36) The water that recharges a groundwater aquifer, after being filtered into the ground,
- accumulates in the aquifer and remains there until it is pumped.
- flows underground but can also flow to the surface.
- flows underground exclusively until it reaches the sea (unless it is pumped by drilling).
37) Is the following statement True or False:
During a test-pumping at an unconfined aquifer, after 20 hours of pumping the water level drop at 30 meters distance from the well was 30 cm and at 60 meters it was 60 cm.
38) During a test pumping in an unconfined aquifer the water level drop s(t, r) was measure at times t1 = 10 min and t2 = 100 min in two observation wells that are r1 = 10 m and r2 = 100 m away from the pumping well. The level of the aquifer s(t, r) is a function of the time from the start of the pumping and the distance from the center of the drilling. Which of the following relationships is WRONG:
- s(t1,r1)> s(t1,r2)
- s(t2,r1)> s(t2,r2)
- s(t1,r1)>s(t2,r1)
39) The water level drop in unconfined aquifers during pumping:
- Is higher for aquifers with higher conductivity (k)
- Is lower for aquifers with higher conductivity (k)
- It increases as the distance from the center of the well increases.
- It decreases as the distance from the center of the well increases.
40) The Akrotiri aquifer is recharged by:
- Direct rainfall and underground escapes from the Kouris reservoir
- Groundwater inflows from the northern part of the hydrological basin connected to the aquifer.
- Irrigation returns and artificial enrichment
- All of the above