# GATE Questions & Answers of Unit hydrographs

## What is the Weightage of Unit hydrographs in GATE Exam?

Total 18 Questions have been asked from Unit hydrographs topic of Hydrology subject in previous GATE papers. Average marks 1.78.

The ordinates of a 2-hour unit hydrograph for a catchment are given as

 Time (h) 0 1 2 3 4 Ordinate (m3/s) 0 5 12 25 41

The ordinate (in m3/s) of a 4-hour unit hybrograph for this catchment at the time of 3 h would be _________

An effective rainfall of 2-hour duration produced a flood hydrograph peak of 200 m3/s. The flood hydrograph has a base flow of 20m3/s. If the spatial average rainfall in the watershed for the duration of strom is 2 cm and the average loss rate is 0.4 cm/hour, the peak of 2-hour unit hydrograph (in m3/s-cm, up to one decimal place) is _____________

At a station, Storm I of 5 hour duration with intensity 2 cm/h resulted in a runoff of 4 cm and Storm II of 8 hour duration resulted in a runoff of 8.4 cm. Assume that the $?$-index is the same for both the storms.

The Φ-index (in cm/h) is:

At a station, Storm I of 5 hour duration with intensity 2 cm/h resulted in a runoff of 4 cm and Storm II of 8 hour duration resulted in a runoff of 8.4 cm. Assume that the $?$-index is the same for both the storms.

The intensity of storm II (in cm/h) is:

The ratio of actual evapo-transpiration to potential evapo-transpiration is in the range

The top width and the depth of flow in a triangular channel were measured as 4 m and 1 m, respectively. The measured velocities on the centre line at the water surface, 0.2 m and 0.8 m below the surface are 0.7 m/s, 0.6 m/s and 0.4 m/s, respectively. Using two-point method of velocity measurement, the discharge (in m3/s) in the channel is

Group I contains parameters and Group II lists methods/instruments.

 Group I Group II P. Streamflow velocity 1. Anemometer Q. Evapo-transpiration rate 2. Penman’s method R. Infiltration rate 3. Horton’s method S. Wind velocity 4. Current meter The CORRECT match of Group I with Group II is

The drainage area of a watershed is 50 km2. The $\mathrm\phi$ index is 0.5 cm/hour and the base flow at the outlet is 10 m3/s. One hour unit hydrograph (unit depth = 1 cm) of the watershed is triangular in shape with a time base of 15 hours. The peak ordinate occurs at 5 hours.

The peak ordinate (in m3/s/cm) of the unit hydrograph is

The drainage area of a watershed is 50 km2. The $\mathrm\phi$ index is 0.5 cm/hour and the base flow at the outlet is 10 m3/s. One hour unit hydrograph (unit depth = 1 cm) of the watershed is triangular in shape with a time base of 15 hours. The peak ordinate occurs at 5 hours.

For a storm of depth of 5.5 cm and duration of 1 hour, the peak ordinate (in m3/s) of the hydrograph is

A watershed got transformed from rural to urban over a period of time. The effect of urbanization on storm runoff hydrograph from the watershed is to

The ordinates of a 2-h unit hydrograph at 1 hour intervals starting from time t=0, are 0,3,8,6,3,2 and 0 m3/s. use trapzodial rule for numerical intergration, if required.

What is the catchment area represented by the unit hydrograph?

The ordinates of a 2-h unit hydrograph at 1 hour intervals starting from time t=0, are 0,3,8,6,3,2 and 0 m3/s. use trapzodial rule for numerical intergration, if required.

A storm of 6.6 cm occurs uniformly over the catchment in 3 hours if ∅ -index is equal to 2mm/h and base flow is 5 m3/s, what is the peak flow due to the storm?

The correct match of Group-I with Group-II is

 Group-I Group-II P. Evapotranspiration 1. Penman method Q. Infiltration 2. Snyder’s method R. Synthetic unit hydrograph 3. Muskingum method S. Channel Routing 4.Horton’s method

One hour triangular unit hydrograph of a watershed has the peak discharge of 60m3/sec.cm at 10 hours and time base of 30 hours. The $\phi$ index is 0.4 cm per hour and base flow is 15 m3/sec.

The catchment area of the watershed is

One hour triangular unit hydrograph of a watershed has the peak discharge of 60m3/sec.cm at 10 hours and time base of 30 hours. The $\phi$ index is 0.4 cm per hour and base flow is 15 m3/sec.

If these is rainfall of 5.4 cm in 1 hour, the ordinate of the flood hydrograph at 15th hour is

An isolated 4-hour storm occurred over a catchment as follows

 Time 1st hour 2nd hour 3rd hour 4th hour Rainfall (mm) 9 28 12 7

The $\mathrm\phi$ index for the catchment is 10 mm/h. The estimated runoff depth from the catchment due to the above storm is

Ordinates of a 1-hour unit hydrograph at 1 hour intervals, starting from time t = 0, are 0, 2, 6, 4, 2, 1 and 0 m3/s.

Catchment area represented by this unit hydrograph is