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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 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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