# Hydrology & Irrigation

## Trending Questions

**Q.**On rolling land, the method of applying water is

- Check flooding
- Free flooding
- Border flooding
- Furrow flooding

**Q.**There are four raingauge stations existing in the catchment of a river. The average annual rainfall values at these stations are 780, 640, 400, 520 mm. Allowable percentage error in mean value of rainfall is 10%. The optimum number of rain gauges in the catchment should be ________.

- 8

**Q.**A 6-hour Unit Hydrograph (UH) of a catchment is triangular in shape with a total time base of 36 hours and a peak discharge of 18 m3/s. The area of the catchment (in sq. km) is

- 233
- 117
- 1.2
- Sufficient information not available

**Q.**A tropical cyclone in a northern hemisphere is a wind stream with

- High pressure zone of anticlockwise rotation.
- High pressure zone of clockwise rotation
- Low pressure zone of anticlockwise rotation
- Low pressure zone of clockwise rotation

**Q.**The parameter in Horton's infiltration equation [f(t)=fc+(f0−fc)e−kt] are given as, f0=7.62 cm/hour , fc=1.34 cm/hour, and k=−4.182/hour. For assumed continuous ponding the cumulative infiltration at the end of 2 hours is

- 2.68 cm
- 1.50 cm
- 1.34 cm
- 4.18 cm

**Q.**A 45 cm diameter well penetrates an unconfined aquifer of 30 m thick. Under the steady pumping rate for a long time, the drawdown at two observation wells 10 m and 20 m from the pumping well are 5 m and 3.5 m respectively. What will be the discharge (cubic metre per sec), if the permeability of the aquifer is given as 20 m/day.

- 0.05
- 0.067
- 0.08
- 1.12

**Q.**Calculate the permanent wilting point if the depth of water in the root zone at the permanent wilting point per meter depth of soil is 0.4m. The dry density of the soil is 16 KN/m³.

- 0.025
- 0.245
- 0.4
- 0.64

**Q.**If the field capacity of a soil is 35%, permanent wilting point is 15%, density of soil is 1.6 g/cm2, effective depth of root zone is 75 cm and daily consumptive use of water for given crop is 14 mm, then the watering frequency to ensure efficient irrigation to the given crop will be ____ days. [Readily available moisture is same as available moisture]

- 17

**Q.**A catchment has six rainguage stations. In a year, the annual rainfall record by the gauges are as follows

Station | A | B | C | D | E | F |

Rainfall (cm) | 76 | 85 | 101 | 130 | 88 | 110 |

For the 12% error in the estimation of mean rainfall, the optimum number of stations required in the catchment are

- 1
- 2
- 3
- 4

**Q.**

What do you mean by integral value?

**Q.**Dickens formula predicts maximum flood discharge, Q, in terms of the area, A, and the coefficient, c, as Q=cAn. The value of n is

- 0.25
- 0.50
- 0.67
- 0.75

**Q.**

What does $\mathrm{S}$ mean in math?

**Q.**The Muskingum method of flood routing is a

- Form of hydraulic routing of a flood
- Form of reservoir routing
- Complete numerical solution of St. Venant equations
- Hydrological channel routing method

**Q.**A launching apron is to be designed at downstream of a weir for discharge intensity of 6.5 m3/s/m. For the design of launching aprons, the scour depth is taken two times of Lacey scour depth. The silt factor of the bed material is unity. If the tailwater depth is 4.4 m, the length of the launching apron in the launched position is

- √5 m
- 4.7 m
- 5 m
- 5√5 m

**Q.**Rainfall hyetograph shows the variation of_____.

- Cumulative rainfall with time
- Rainfall intensity with time
- Rainfall depth over an area
- Rainfall intensity with the cumulative rainfall

**Q.**Specific capacity of a well is the

- Volume of water that can be extracted by the force of gravity from a unit volume of aquifer
- discharge per unit drawdown of the well
- drawdown per unit discharge of the well
- rate of flow through a unit width and entire thickness of aquifer

**Q.**Depth-Area-Duration curves of precipitation are drawn as

- minimizing envelopes through the appropriate data points
- maximizing envelopes through the appropriate data points
- best fit mean curves through the appropriate data points
- best fit mean straight lines through the appropriate data points

**Q.**The intensity of Irrigation means

- Percentage of cultivable commanded area to be irrigated annually
- Percentage of gross commanded area to be irrigated annually
- Percentage of the mean of culturable commanded area and the gross commanded area to be irrigated annually
- The total depth of water supplied by the number of waterings

**Q.**The field irrigation requirement is computed as ___.

- Consumptive use + field application losses
- Net irrigation requirement + field application losses
- Net irrigation requirement + conveyance losses
- Consumptive use + conveyance losses

**Q.**The rate of rainfall for successive 30 minutes period of a 4−hour storm are as follows:

3.5, 6.5, 8.5, 7.5, 6.4, 4.0, 4.0, 6.0 cm/hr. If the value of ϕ−index is 4.5 cm/hr, then the value of W- index (cm/hr) is

- 5.5
- 4.13
- 4.25
- 3.9

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

- 676 m2/day
- 576 m2/day
- 526 m2/day
- 249 m2/day

**Q.**The area between the two isohyetes 45 cm and 55 cm is 100 km2 and that between 55 cm and 65 cm is 150 km2. What is the average depth of annual precipitation over the basin of 250 km2

- 50 cm
- 52 cm
- 56 cm
- 60 cm

**Q.**The return period for the annual maximum flood of a given magnitude is 8 years. The probability that this flood magnitude will be exceeded once during the next 5 years is

- 0.625
- 0.366
- 0.487
- 0.529

**Q.**

Lacey's scour depth for a stream carrying a discharge of 3 cumecs per meter width having a silt factor 1.2 is_____m

- 2.64

**Q.**The Thiessen polygon is

- a polygon obtained by joining adjoining rainguage stations.
- a representative area used for weighing the observed station precipitation.
- an area used in the construction of depth area curves
- the descriptive term for shape of a hydrograph

**Q.**Which one is the best method of the reclaimation of the acidic soil ?

- Leaching
- Provision of good drainage
- Use gypsum as a soil amendment
- Use limestone as a soil amendment

**Q.**A small catchment of area 150 ha received a rainfall of 10.5 cm in 90 minutes, due to a storm. At the outlet of the catchment, the stream draining the catchment was dry before the storm and experiences a runoff for 10 hours with an average discharge value of 2.5 m3/sec.The stream was again dry after the runoff event. The amount of water which was not available to runoff due to combined effect of infiltration, evaporation and transpiration is ____ m3

- 96×104
- 67500
- 247500
- 114×104

**Q.**An accurate estimate of average rainfall in a particular catchment area can be obtained by

- arithmetic mean method
- isohyetal method
- normal ratio method
- Thiessen method

**Q.**A 6-hour rainstorm with hourly intensities of 7, 18, 25, 12, 10 and 3 mm per hour produced a run-off of 33 mm. Then the ϕ− index is

- 7 mm/h
- 3 mm/h
- 10 mm/h
- 8 mm/h

**Q.**If the irrigation efficiency is 80%, conveyance losses are 20% and the actual depth of watering is 16 cm, the depth of water required at the canal outlet is

- 10 cm
- 15 cm
- 20 cm
- 25 cm