Hydrology and Ground Water

21. A well penetrates to 30 m below the static water table. After 24 hours of pumping at 31.40 litres/minute, the water level in a test well at a distance of 80 m is lowered by 0.5 m and in a well 20 m away water is lowered by 1.0 m. The transmissibility of the aquifer, is

1. 1.185 m²/minute
2. 1.285 m²/minute
3. 1.385 m²/minute
4. 1.485 m²/minute

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22. Absolute humidity in air

1. Decreases at higher altitudes
2. Increases at higher altitudes
3. Remains constant at all altitudes
4. None of these

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23. According to Khosla's theory, the exit gradient in the absence of a downstream cut-off is

1. 0
2. Unity
3. Infinity
4. Very large

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24. According to Robert E. Horton, the equation of infiltration capacity curve, is (where letters carry their usual meanings)

1. f = f_c (f_o - fc) e_kt
2. f = f_t - (f_o - fc) e-_kt
3. f = f_t + (f_o - fc) e-_kt
4. f = f + (f_o - fc) e_kt

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25. Aetted perimeter of regime channel for a discharge of 64 cumecs as per Lacey's theory will be

1. 9 m
2. 8 m
3. 7 m
4. 6 m

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26. An aggrading river is a

1. Silting river
2. Scouring river
3. Both silting and scouring river
4. Neither silting nor scouring river

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27. An intense rain is falling at a uniform rate of 7.5 cm/hour for a period of 60 minutes on a basin whose area is 500 hectares. If the average infiltration capacity during the entire rain period is assumed to be 1.5 cm/hr, the maximum run-off rate based on 10 minute peak percentage of 16% from distributing graph of the basin, is

1. 40 cumecs
2. 60 cumecs
3. 80 cumecs
4. 100 cumecs

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28. As compared to crest of the normal portion of the weir, the crest of the under sluice portion of weir is kept at

1. Lower level
2. Higher level
3. Same level
4. Any of the above depending on the design

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29. As compared to gravity dams, earthen dams

1. Are costlier
2. Are less susceptible to failure
3. Require sound rock foundations
4. Require less skilled labour

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30. As per Lacey's theory, the silt factor is

1. irectly proportional to average particle size
2. nversely proportional to average particle size
3. irectly proportional to square root of average particle size
4. ot related to average particle size

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