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Target 2021 weekly quiz (App update required to attempt this test)

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Question 1

If permissible error in estimation of mean rainfall is reduced by half, the additional number of rain gauges required will be __________ times the present number of rain gauges.

Question 2

Find the evaporation from a 8m wide canal from its total length of 160 kms. It is given that the average evaporation measured from class A pan was 0.63 cm/day. Then the volume of water evaporated in one month is ____ m3

Question 3

Initially the depth of water in an evaporation pan was 6.25 mm. After 7 days, the depth of water was 7.80 mm. In this period a rainfall of 5.72 mm occurred, and 1.5 mm of water was taken out from it. Assuming pan coefficient = 0.7 estimate the evaporation from a reservoir having similar conditions.

Question 4

Which one of the following are the methods to determine Potential Evapotranspiration (PET)
1) Thornwaite method
2) Modified Penman Method
3) Jansen-Haise method
4) Hargreaves method
Choose the correct option using below codes:

Question 5

The level of water in the reservoir is 1.25 m. If there is a rainfall of 38 cm occurring in a month, during this period evaporation as measured by the class A pan is 32 cm. What is the level of water in m at the end of the month.

Question 6

Five rain gauge stations A, B, C, D and E recorded rainfall of 120cm, 80cm, 100cm, 90cm and 130cm respectively. The rain gauge stations are located on a circular shape catchment having diameter 40km as shown in the figure. Calculate the mean rainfall over the catchment using Thiessen’s Polygon method.

Question 7

Following is the set of observed data for successive 15 minutes period of 90-minutes storm in a catchment.

If the value of Φ-index is 3 cm/hour, the value of w-index will be

Question 8

Five rain gauges are located on a basin as shown in figure. What will be the mean rainfall (in cm) over the basin using Thiessen Polygon method, if the rainfall at stations A, B, C, D and E are 10 cm, 8 cm, 11 cm, 12 cm and 9 cm respectively?

Question 9

A catchment is idealized as a 25 km x 25 km square. It has five rain gauges, one at each corner and one at the center, as shown in the figure.

During a month, the precipitation at these gauges is measured as G1 = 300 mm, G2 = 285 mm, G3 = 272mm, G4 = 290mmand G5 =288mm. The average precipitation (in mm, up to one decimal place) over the catchment during this month by using the Thiessen polygon method is ______

Question 10

A reservoir has an average area 20 km2 throughout an year. The mean inflow rate = 20 m3/s, mean outflow rate = 15 m3/s, monthly rainfall = 10 cm, annual seepage loss = 21.6 cm and change in storage is 16 million m3. Find the total evaporation in one year in million m3.

Question 11

A catchment has an area of 120ha and a runoff to rainfall ratio of 0.35. If due to 10cm rainfall over the catchment the stream flow lasts for 6h, the average stream flow in this period is ______ m3/s.

Question 12

During a 3 hour storm event, it was observed that all abstractions other than infiltration are negligible. The rainfall was idealized as 3 one hour storms of intensity 10 mm/hr, 20 mm/hr and 10 mm/hr respectively and the infiltration was idealized as a Horton curve, f = 6.8 + 8.7 exp (- t) (f in mm/hr and t in hr). What is the effective rainfall?

Question 13

The rainfall during three successive 2 hour periods are 0.5, 2.8 and 1.6 cm. The surface runoff resulting from this storm is 3.2 cm. The 100% index value of this storm is

Question 14

The infiltration capacity of a soil follows the Horton's exponential model, f = c, During and experiment, the initial infiltration capacity was observed to be 200 mm/h. After a long time, the infiltration capacity was reduced to 25 mm/h. If the infiltration capacity after 1 hour was 90 mm/h, the value of the decay rate constant, k (in 11', up to two decimal places) is____

Question 15

Rainfall over a basin in three consecutive hours are 3.5 cm, 4 cm and 3 cm respectively. The infiltration loss can be estimated using the following Horton equation

f = 0.9 + 3.8 e-2t

where f is infiltration in cm/hr and t = time in hour from start of rainfall.

Assuming negligible surface retention and evaporation losses, the surface run off from the basin is _______ cm [Rounded to two decimal places]

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