Infiltration Runoff And Hydrographs Practice Questions

The peak of flood hydrograph due to a 3-hour duration storm in a catchment is 180 $\text{m}^3/\text{s}$ . The total rainfall depth is 6.6 cm. It can be assumed that the average infiltration loss is 0.2 cm/h. There are no other losses. The base flow is constant at a value of 30 $\text{m}^3/\text{s}$ . The peak value of the 3-hour unit hydrograph for this catchment (in $\text{m}^3/\text{s}$ ) is ______ (round off to the nearest integer).

To derive the total flood hydrograph at a catchment outlet from an isolated storm, the order in which the following methods are applied, from the first method to the last method, is P. Obtaining the hyetograph Q. Addition of baseflow R. Estimation of initial and infiltration losses S. Application of unit hydrograph

The ordinates of a 1-hour unit hydrograph $(\mathrm{UH})$ are given below. These ordinates are used to derive a 3-hour UH. The peak discharge (in $\mathrm{m}^{3} / \mathrm{s}$ ) for the derived 3-hour UH is ______(rounded off to the nearest integer).

A storm with a recorded precipitation of $11.0 \mathrm{~cm}$ , as shown in the table, produced a direct run-off of $6.0 \mathrm{~cm}$

The $\phi$ -index of this storm is ____ $\mathrm{cm} / \mathrm{hr}$ (rounded off to 2 decimal places)

Which one of the following options provides the correct match of the terms listed in Column-I and Column-2 ?

In Horton's equation fitted to the infiltration data for a soil, the initial infiltration capacity is $10 \mathrm{~mm} / \mathrm{h}$ ; final infiltration capacity is $5 \mathrm{~mm} / \mathrm{h}$ ; and the exponential decay constant is $0.5 \mathrm{~h}$ . Assuming that the infiltration takes place at capacity rates, the total infiltration depth (in $\mathrm{mm}$ ) from a uniform storm of duration $12 \mathrm{~h}$ is ____. (round off to one decimal place)

The ordinates of a one-hour unit hydrograph for a catchment are given below :

Using the principle of superposition, a D-hour unit hydrograph for the catchment was derived from the one-hour unit hydrograph. The ordinate of the D-hour unit hydrograph were obtained as $3 \mathrm{~m}^{3} / \mathrm{s}$ at $t=1$ hour and $10 \mathrm{~m}^{3} / \mathrm{s}$ at $t=2$ hour. the value of $D$ (in integer) is _____

A 12-hour storm occurs over a catchment and results in a direct runoff depth of $100 \mathrm{~mm}$ . The time-distribution of the rainfall intensity is shown in the figure (not to scale). The $\phi$ -index of the storm is (in $\mathrm{mm}$ , rounded off to two decimal places)_____

A two-hour duration storm event with uniform excess rainfall of 3 cm occurred on a watershed. The ordinates of streamflow hydrograph resulting from this event are given in the table.

Considering a constant baseflow of 10 $m^3/s$ , the peak flow ordinate (in $m^3/s$ ) of one-hour unit hydrograph for the watershed is ________ . (in integer)

A 12-hour unit hydrograph (of 1 cm excess rainfall) of a catchment is of a triangular shape with a base width of 144 hour and a peak discharge of $23 \mathrm{~m}^{3} / \mathrm{s}$ . The area of the catchment (in $\mathrm{~km}^{2}$ ,round off to the nearest integer) is _______

The value of abscissa (x) and ordinate (y) of a curve are as follows:

By Simpson's $1 / 3^{\mathrm{rd}}$ rule, the area under the curve (round off to two decimal places) is ______________

The hyetograph in the figure corresponds to a rainfall event of 3 cm. If the rainfall event has produced a direct runoff of 1.6 cm, the $\phi$ -index of the event (in mm/hour,round off to one decimal place) would be

The probability that a 50 year flood may NOT occur at all during 25 years life of a project (round off to two decimal places), is _______.

A triangular direct runoff hydrograph due to a storm has a time base of 90 hours. The peak flow of 60 $m^3/s$ occurs at 20 hours from the start of the storm. The area of catchment is 300 $km^2$ . The rainfall excess of the storm (in cm), is

The ordinates, u, of a 2-hour unit hydrograph (i.e., for 1 cm of effective rain), for a catchment are shown in the table. A 6-hour storm occurs over the catchment such that the effective rainfall intensity is 1 cm/hour for the first two hours, zero for the next two hours, and 0.5 cm/hour for the last two hours. If the base flow is constant at 5 $m^3/s$ , the peak flow due to this storm (in $m^3/s$ ,round off to 1 decimal place) will be _____

An inflow hydrograph is routed through a reservoir to produce an outflow hydrograph. The peak flow of the inflow hydrograph is $P_I$ and the time of occurrence of the peak is $t_I$ . The peak flow of the outflow hydrograph is $P_O$ and the time of occurrence of the peak is $t_O$ . Which one of the following statements is correct?

The hyetograph of a storm event of duration 140 minutesis shown in the figure. The infiltration capacity at the start of this event (t=0) is 17 mm/hour, which linearly decreases to 10 mm/hour after 40 minutes duration. As the event progresses, the infiltration rate further drops down linearly to attain a value of 4 mm/hour at t=100 minutes and remains constant thereafter till the end of the storm event. The value of the infiltration index, $\phi$ (in mm/hour, round off to 2 decimal places), is _______

The total rainfall in a catchment of area $1000\: km^{2}$ , during a 6 h storm, is 19 cm. The surface runoff due to this storm computed from triangular direct runoff hydrograph is $1 \times 10^8 m^{3}$ . The $\phi _{index}$ for this storm (in cm/h, up to one decimal place) is ______

The infiltration rate f in a basin under ponding condition is given by $f=30+10e^{-2t}$ , where, 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 ______