Irrigation (181-200)

Updated: Apr 25, 2020

181. According to Indian standards, the number of raingauge stations for an area of 5200 km² in plains should be 10


182. For a storm of given duration, if the intensity of storm corresponding to a

return period of T is I, then the intensity of storm for same duration but corresponding to a return period of T (where T > T) will be greater than I


183. What is the probability of a flood equal to or greater than 25 years flood occurring twice in the next three years ? 72/15625


184. The rainfall in four successive 12 hours period on a catchment are 40, 80, 90 and 30 mm. If the infiltration index Φ for the storm is 5 mm/hour, then the total surface run off will be 50 mm


185. The 6-hour unit hydrograph of a catchment of area 180km2 ia triangular in

shape. If the peak ordinate of this hydrograph is 10 mVsec, then the time

base is 100 hours


186. Percentage of raingauge stations which should be equipped with self recording gauges for knowing the intensity of rainfall should be about 10%


187. If the same catchment area is situated in three zones X, Y, Z where X, Y and Z

represent flat regions of tropical zone, mountaneous region of tropical zone and

arid zone respectively, then the relation between the desirable number of

raingauge stations in these three zones Nx ,Ny and Nz respectively is

Ny > Nx > Nz


188. If the coefficient of variation of rainfall values at 4 raingauge stations is 30% and permissible error in the estimation of mean rainfall is 10%, then the additional number of raingauge stations required in the catchment is 5


189. Assertion A : Under identical conditions, the evaporation from sea water is less than that from fresh water.

Reason R : Vapour pressure of sea water is less than that of pure water

Both A and R are true and R is the correct explanation of A


190. In a siphon aqueduct the most severe condition of uplift on the floor occurs

when canal is dry and drain is at high flood level


191. The double mass analysis is adopted to check the consistency of data


192. Retrogression of downstream levels, generally considered in the design of

weirs or barrages, is higher at low water levels stage than at high flood stage


193. Cross-regulators in main canals are provided to head up water for adequate supply into the off-taking channel


194. For a barrage, the exit gradient is independent of the depth of upstream cutoff


195. For the upstream slope of an earth dam, the most critical condition is sudden draw down condition


196. Bligh's creep theory of seepage assumes equal weightage to horizontal and

vertical creeps


197. The sequent peak algorithm is a method used in the estimation of the

minimum reservoir capacity needed to meet a given demand


198. The probable maximum flood is an extremely large but physically

possible flood in the region


199. The probable maximum precipitation at a station is the greatest rainfall for a given duration that is physically possible


200. The flow duration curve is a plot of the stream discharge against the

percentage of time the flow is equalled or exceeded

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