GATE Questions & Answers of Hydrology Civil Engineering

Hydrology 46 Question(s)

For routing of flood in a given channel using the Muskingum method, two of the routing coefficients are estimated as $\style{font-family:'Times New Roman'}{C_0=-0.25\;and\;C_1=0.55}$. The value of the third coefficient $C_2$ would be ______

Rainfall depth over a watershed is monitored through six number of well distributed rain gauges. Gauged data are given below

 Rain Gauge Number 1 2 3 4 5 6 Rainfall Depth (mm) 470 465 435 525 480 510 Area of Thiessen Polygon ($\style{font-family:'Times New Roman'}\times$104 m2) 95 100 98 80 85 92

The Thiessen mean value (in mm, up to one decimal place) of the rainfall is ______

The infiltration rate $\style{font-family:'Times New Roman'}f$ in a basin under ponding condition is given by $\style{font-family:'Times New Roman'}{f=30+10\;e^{-2t}}$, where, $\style{font-family:'Times New Roman'}f$ is in mm/h and t is time in hour. Total depth of infiltration (in mm, up to one decimal place) during the last 20 minutes of a storm of 30 minutes duration is ______

Dupuit’s assumptions are valid for

A culvert is designed for a flood frequency of 100 years and a useful life of 20 years. The risk involved in the design of the culvert (in percentage, up to two decimal places) is ______

The total rainfall in a catchment of area 1000 km2 , during a 6 h storm, is 19 cm. The surface runoff due to this storm computed from triangular direct runoff hydrograph is $1\times10^8$m3 . The $\phi_{index}$ for this storm (in cm/h, up to one decimal place) is ______

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 _____________

During a storm event in a certain period, the rainfull intensity is 3.5 cm/hour and the $\style{font-family:'Times New Roman'}{\mathrm\Phi}$ -index is 1.5 cm/hour. The intensity of effective rainfall (in cm/hour, up to one decimal place)  for this period is _____________

The infiltration capacity of a soil follows the Horton's exponetial model, $\style{font-family:'Times New Roman'}{f=c_1+c_2e^{-kt}}$. During an experiment the inital 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 h-1 up to two decimal places) is ____________.

A catchment is idealized as a 25km × 25km 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=272 mm, G4=290 mm and G5=288 mm. The average precipitation (in mm, up to one decimal place) over the catchment  during this month by using the Thiessen polygon method is _____________

The direct runoff hydrograph in response to 5 cm rainfall excess in a catchment is shown in the figure. The area of the catchment (expressed in hectares) is _________. The type of flood routing (Group I) and the equation (s) used for the purpose (Group II) are given below.

 Group I Group II P   Hydrologic flood routing 1.  Continuity equation Q   Hydraulic flood routing 2.  Momentum equation 3.  Energy equation

Water table of an aquifer drops by 100 cm over an area of 1000 km2. The porosity and specific retention of the aquifer material are 25% and 5%, respectively. The amount of water (expressed in km3) drained out from the area is _________

The ordinates of a one-hour unit hydrograph at sixty minute interval are 0, 3, 12, 8, 6, 3 and 0 m3/s. A two-hour storm of 4 cm excess rainfall occurred in the basin from 10 AM. Considering constant base flow of 20 m3/s, the flow of the river (expressed in m3/s) at 1 PM is _________

A tracer takes 100 days to travel from Well-1 to Well-2 which are 100 m apart. The elevation of water surface in Well-2 is 3 m below that in Well-1. Assuming porosity equal to 15%, the coefficient of permeability (expressed in m/day) is

In a catchment, there are four rain – gauge stations, P,Q,R, and S. Normal annual precipitation values at these stations are 780 mm, 850 mm, 920 mm, and 980 mm, respectively. In the year 2013, stations QR, and S, were operative but P was not. Using the normal ratio method, the precipitation at station P for the year 2013 has been estimated as 860 mm. If the observed precipitation at stations Q and R for the year 2013 were 930 mm and 1010 mm, respectively, what was the observed precipitation (in mm) at station S for that year ?

The 4-hr unit hydrograph for a catchment is given in the table below. What would be the maximum ordinate of the S-curve (in m3/s) derived from this hydrograph ?

 Time (hr) 0 2 4 6 8 10 12 14 16 18 20 22 24 Unit hydrograph ordinate (m3/s) 0 0.6 3.1 10 13 9 5 2 0.7 0.3 0.2 0.1 0

A hydraulic jump takes place in a frictionless rectangular channel. The pre-jump depth is yp. The alternate and sequent depths corresponding to yp are ya and ys respectively. The correct relationship among yp, ya and ys is:

The relationship between porosity ($\eta$), specific yield (Sy) and specific retention (Sr) of an unconfined aquifer is:

A triangular gate with a base width of 2 m and a height of 1.5 m lies in a vertical plane. The top vertex of the gate is 1.5 m below the surface of a tank which contains oil of specific gravity 0.8. Considering the density of water and acceleration due to gravity to be 1000 kg/m3 and 9.81 m/s2 respectively, the hydrostatic force (in kN) exerted by the oil on the gate is _________.

In reservoirs with an uncontrolled spillway, the peak of the plotted outflow hydrograph

An isolated 3-h rainfall event on a small catchment produces a hydrograph peak and point of inflection on the falling limb of the hydrograph at 7 hours and 8.5 hours respectively, after the start of the rainfall. Assuming, no losses and no base flow contribution, the time of concentration (in hours) for this catchment is approximately

The Muskingum model of routing a flood through a stream reach is expressed as O2=K0I2+K1I1+K2O1 where K0,K1 and K2 are the routing coefficients for the concerned reach, I1 and I2 are the inflows to the reach, and O1 and O2 are the outflows from the reach corresponding to time steps 1 and 2 respectively. The sum of ,K0 K1 and K2 of the model is

A 1-h rainfall of 10 cm magnitude at a station has a return period of 50 years. The probability that a 1-h rainfall of magnitude 10 cm or more will occur in each oftwo successive years is:

An isohyet is a line joining points of

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

The depth of flow in an alluvial channel is 1.5 m. If critical velocity ratio is 1.1 and Manning’s n is 0.018, the critical velocity of the channel as per Kennedy’s method 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.

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

A flood wave with a known inflow hydrograph is routed through a large reservoir. The outflow hydrograph will have

A stable channel is to be designed for a discharge of Q m3/s with silt factor f as per Lacey’s method. The mean flow velocity (m/s) in the channel is obtained by

As per the Lacey’s method for design of a alluvail channels, identify the TRUE statement from the following:

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