Please keep at least one language enabled. || కనీసం ఒక భాషను ఎంచుకోండి.
Question 1
ప్రశ్న 1
Which statement correctly defines a D-hour unit hydrograph of a catchment?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
A unit hydrograph represents the direct-runoff response of a particular catchment. The rainfall input is one unit depth of effective rainfall rather than gross precipitation. That effective rainfall is assumed to be uniformly distributed over the basin and supplied at a uniform rate during the specified duration D. The duration is therefore an essential part of the definition of a unit hydrograph. Hence Option A is correct.
వివరణ:
Question 2
ప్రశ్న 2
Why must effective rainfall rather than gross storm rainfall be used when deriving or applying a conventional unit hydrograph?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Gross precipitation includes water that may be lost to interception, infiltration, depression storage and other abstractions. The rainfall that remains available to produce the modeled direct-runoff response is termed effective rainfall or rainfall excess. Unit-hydrograph theory establishes a transformation between this effective rainfall and the direct-runoff hydrograph. Using gross rainfall without accounting for losses would generally overestimate the input responsible for direct runoff. Therefore Option A is correct.
వివరణ:
Question 3
ప్రశ్న 3
Under the proportionality assumption of unit-hydrograph theory, if 1 cm of D-hour effective rainfall produces a unit-hydrograph ordinate of 30 m³/s at a certain time, what ordinate is produced at the corresponding time by 2.5 cm of effective rainfall of the same duration and distribution?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The proportionality assumption states that direct-runoff ordinates are directly proportional to effective-rainfall depth for inputs of the same duration. A depth of 2.5 cm is 2.5 times the unit depth of 1 cm. Therefore the corresponding discharge ordinate is 2.5 × 30 = 75 m³/s. The hydrograph time scale remains unchanged under this simple scaling assumption. Hence Option C is correct.
వివరణ:
Question 4
ప్రశ్న 4
What does time invariance mean in conventional unit-hydrograph theory?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Time invariance means that the response characteristics of the modeled catchment are assumed not to change with the absolute time at which an input occurs. If an identical effective-rainfall pulse is delayed by several hours, its runoff response is correspondingly delayed by the same amount. The shape and magnitude of the response remain unchanged under the assumption. Real catchments may deviate from this ideal because antecedent moisture and routing conditions can change. Therefore Option A is correct.
వివరణ:
Question 5
ప్రశ్న 5
Which statement is consistent with the basic unit-hydrograph assumptions for two storms having effective rainfall of the same duration over the same catchment?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Conventional unit-hydrograph theory treats the catchment as an approximately linear system for the intended range of application. Effective-rainfall inputs having the same duration are therefore represented using the same unit-hydrograph response pattern. Increasing the effective-rainfall depth scales the direct-runoff ordinates through proportionality. The time base is not assumed to increase merely because the rainfall-excess depth is larger. Hence Option A is correct.
వివరణ:
Question 6
ప్రశ్న 6
Which sequence is most appropriate for deriving a D-hour unit hydrograph from a suitable isolated storm?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The observed storm hydrograph contains both direct runoff and base flow. Base-flow separation is therefore first required to isolate the direct-runoff hydrograph. The area under that hydrograph gives direct-runoff volume, which can be expressed as an equivalent depth over the catchment. Under the unit-hydrograph assumptions, each direct-runoff ordinate is then normalized by the corresponding effective-runoff depth expressed in unit-depth terms. Therefore Option A gives the correct derivation sequence.
వివరణ:
Question 7
ప్రశ్న 7
An isolated storm of 2-hour effective-rainfall duration produces 2.5 cm of effective rainfall. Its direct-runoff hydrograph ordinates at 2-hour intervals are 0, 25, 75, 50 and 0 m³/s. What is the peak ordinate of the corresponding 2-hour, 1-cm unit hydrograph?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The direct-runoff hydrograph is produced by 2.5 cm of effective rainfall. Under proportionality, the 1-cm unit hydrograph is obtained by dividing every direct-runoff ordinate by 2.5. The peak ordinate therefore becomes 75/2.5 = 30 m³/s. The other ordinates would similarly become 0, 10, 30, 20 and 0 m³/s. Therefore Option B is correct.
వివరణ:
Question 8
ప్రశ్న 8
A unit hydrograph is defined for 1 cm of effective rainfall over a 20 km² catchment. If the unit hydrograph is idealized as a triangle with a base time of 10 h, what peak discharge is required so that its volume satisfies the unit-depth condition?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
One centimetre of runoff over 20 km² corresponds to 0.01 × 20,000,000 = 200,000 m³. The area under the triangular hydrograph must equal this volume. Its area is 0.5 × Qp × 10 × 3600. Setting this equal to 200,000 gives Qp = 400,000/36,000 = approximately 11.1 m³/s. Therefore Option B is correct.
వివరణ:
Question 9
ప్రశ్న 9
A 3-hour unit hydrograph has ordinates 0, 15, 45, 30 and 0 m³/s at successive 3-hour intervals. What direct-runoff hydrograph results from 3 cm of uniformly distributed effective rainfall lasting 3 hours?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The given hydrograph corresponds to one unit depth of effective rainfall. The required effective-rainfall depth is 3 cm and has the same duration. By proportionality, each unit-hydrograph ordinate is multiplied by three. This gives 0, 45, 135, 90 and 0 m³/s. Hence Option C is correct.
వివరణ:
Question 10
ప్రశ్న 10
If the same D-hour unit effective-rainfall pulse occurs 4 hours later than another identical pulse, what does time invariance imply about its direct-runoff hydrograph?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Time invariance allows a catchment response to be shifted in time without changing the response function itself. The second effective-rainfall pulse is identical to the first except for its occurrence time. Its direct-runoff hydrograph therefore has the same ordinates and shape. Every point on that response simply occurs 4 hours later. Therefore Option A is correct.
వివరణ:
Question 11
ప్రశ్న 11
What is meant by the principle of superposition in unit-hydrograph analysis?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Superposition follows from the assumed linearity of the unit-hydrograph model. Each block of effective rainfall produces a scaled copy of the appropriate unit hydrograph. The copies are shifted according to the occurrence times of their corresponding rainfall blocks. Where several responses overlap, their discharges are added at the same time ordinate. Therefore Option A is correct.
వివరణ:
Question 12
ప్రశ్న 12
A 1-hour unit hydrograph has ordinates 0, 10, 30, 20 and 0 m³/s at times 0, 1, 2, 3 and 4 h. Consecutive 1-hour effective-rainfall depths are 2 cm followed by 1 cm. What is the peak discharge of the resulting direct-runoff hydrograph?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The first 2-cm pulse produces ordinates 0, 20, 60, 40 and 0 m³/s. The second 1-cm pulse produces the original unit hydrograph shifted by one hour. Adding the two responses gives 0, 20, 70, 70, 20 and 0 m³/s. The maximum direct-runoff discharge is therefore 70 m³/s. Hence Option C is correct.
వివరణ:
Question 13
ప్రశ్న 13
In discrete unit-hydrograph convolution, what does each direct-runoff ordinate represent?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Each effective-rainfall block generates its own scaled unit-hydrograph response. Because these responses persist for several time intervals, several shifted hydrographs may overlap at a particular time. The direct-runoff discharge at that time is the sum of all such active contributions. Mathematically this is a discrete convolution of effective rainfall with the unit-hydrograph ordinates. Therefore Option A is correct.
వివరణ:
Question 14
ప్రశ్న 14
A 1-hour unit hydrograph has ordinates 0, 10, 30, 20 and 0 m³/s. The first 1-hour rainfall-excess block is 1 cm and the second consecutive block has unknown depth x. If the direct-runoff ordinate at time 2 h is 50 m³/s, what is x?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
At time 2 h, the first 1-cm pulse contributes the unit-hydrograph ordinate of 30 m³/s. The second pulse began one hour later and therefore contributes x times the 1-hour unit-hydrograph ordinate of 10 m³/s. Thus 30 + 10x = 50. Solving gives x = 2 cm. Therefore Option B is correct.
వివరణ:
Question 15
ప్రశ్న 15
After a unit-hydrograph calculation has produced a direct-runoff hydrograph, what is generally required to obtain a corresponding total streamflow or flood hydrograph?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
A conventional unit hydrograph represents the direct-runoff component rather than total streamflow. Observed flood flow can also contain groundwater-derived base flow and other slow-flow contributions. After the direct-runoff hydrograph is generated, an appropriate base-flow estimate may therefore be added ordinate by ordinate. The resulting sum represents the modeled total stormflow hydrograph. Hence Option A is correct.
వివరణ:
Question 16
ప్రశ్న 16
A storm produces 5 cm of gross rainfall during the unit duration, but hydrologic abstractions amount to 3 cm, leaving 2 cm of effective rainfall. Which depth should multiply the unit-hydrograph ordinates?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The unit hydrograph transforms effective rainfall into direct runoff. Of the 5 cm gross rainfall, 3 cm is removed by the stated abstractions. Only 2 cm remains as rainfall excess. Therefore the unit-hydrograph ordinates must be scaled by 2 rather than by 5. Hence Option A is correct.
వివరణ:
Question 17
ప్రశ్న 17
A 2-hour unit hydrograph is available, but the effective-rainfall input is to be represented as uniform 4-hour blocks. Which statement is most appropriate?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Unit-hydrograph duration is tied to the duration of the effective-rainfall pulse that defines it. A 2-hour unit hydrograph therefore represents a different input pulse from a 4-hour unit hydrograph. Before directly applying uniform 4-hour effective-rainfall blocks, the response function should be converted to the corresponding duration. For integer multiples, superposition provides a convenient conversion procedure. Therefore Option A is correct.
వివరణ:
Question 18
ప్రశ్న 18
A 2-hour unit hydrograph has ordinates 0, 20, 50, 30 and 0 m³/s at 2-hour intervals. Using superposition, what are the ordinates of the corresponding 4-hour unit hydrograph at 2-hour intervals?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Place two copies of the 2-hour unit hydrograph consecutively, with the second shifted by 2 hours. Their summed ordinates are 0, 20, 70, 80, 30 and 0 m³/s. This combined response corresponds to 2 units of effective rainfall uniformly supplied over the total 4-hour period. Dividing the ordinates by two restores one unit depth and gives 0, 10, 35, 40, 15 and 0 m³/s. Therefore Option B is correct.
వివరణ:
Question 19
ప్రశ్న 19
If an nD-hour unit hydrograph is to be obtained from a D-hour unit hydrograph where n is a positive integer, which procedure is correct under the unit-hydrograph assumptions?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Each D-hour unit hydrograph corresponds to one unit depth supplied over D hours. Placing n such inputs consecutively produces n units of effective rainfall over nD hours. Their runoff hydrographs are shifted by D hours and added through superposition. The combined hydrograph therefore corresponds to n units rather than one unit. Dividing all ordinates by n gives the required nD-hour unit hydrograph, so Option A is correct.
వివరణ:
Question 20
ప్రశ్న 20
What does an S-hydrograph or S-curve represent in unit-hydrograph analysis?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
An S-hydrograph is formed by repeatedly applying the available D-hour unit effective-rainfall pulse. Successive D-hour unit hydrographs are therefore lagged by D hours and summed. This represents a continuous effective-rainfall supply of constant intensity extending indefinitely. The S-curve eventually approaches an equilibrium discharge when the catchment response to the continuous input becomes steady. Therefore Option A is correct.
వివరణ:
Question 21
ప్రశ్న 21
An S-curve is constructed from a D-hour unit hydrograph. To derive a T-hour unit hydrograph, the S-curve is subtracted from a copy lagged by T hours. Why must the resulting difference hydrograph be multiplied by D/T?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The original S-curve represents continuous effective rainfall at a rate of one unit depth per D hours. A difference between two such curves separated by T hours therefore isolates an effective-rainfall block having depth T/D units. The resulting difference hydrograph is consequently not yet a one-unit hydrograph unless T equals D. Multiplication by D/T normalizes the runoff response to one unit depth. Therefore Option A is correct.
వివరణ:
Question 22
ప్రశ్న 22
An S-curve has been formed from a 3-hour unit hydrograph. At a particular time, the difference between the original S-curve and a copy lagged by 6 hours is 80 m³/s. What is the corresponding ordinate of the derived 6-hour unit hydrograph?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The available unit duration is D = 3 hours and the desired duration is T = 6 hours. The S-curve difference corresponds to T/D = 6/3 = 2 units of effective rainfall. To obtain a one-unit 6-hour hydrograph, the difference ordinate must be multiplied by D/T = 3/6 = 0.5. Thus the required ordinate is 0.5 × 80 = 40 m³/s. Therefore Option B is correct.
వివరణ:
Question 23
ప్రశ్న 23
Why is the S-curve method especially useful for unit-hydrograph duration conversion?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Simple superposition is particularly convenient when the desired duration is an integer multiple of the available duration. The S-curve provides a more general duration-conversion framework. By lagging the S-curve by the desired duration, differencing it and applying the appropriate depth correction, shorter or longer durations can be obtained even when the desired duration is not an integer multiple. The method still relies on the fundamental assumptions underlying unit-hydrograph theory. Therefore Option A is correct.
వివరణ:
Question 24
ప్రశ్న 24
Which circumstance most directly challenges the accuracy of conventional unit-hydrograph predictions?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The conventional unit-hydrograph method relies on approximate linearity and time invariance. Real catchments can violate these assumptions when soil saturation, floodplain storage, channel routing or runoff-producing areas change greatly with storm magnitude or antecedent conditions. Under such circumstances, a hydrograph obtained by simple proportional scaling may not represent the actual response accurately. Unit choice alone does not create such a physical limitation if conversions are handled consistently. Therefore Option A is correct.
వివరణ:
Question 25
ప్రశ్న 25
Consider the following statements about unit-hydrograph theory: I. A D-hour unit hydrograph corresponds to one unit depth of effective rainfall occurring uniformly over the catchment during D hours. II. Under proportionality, multiplying effective-rainfall depth by a factor multiplies corresponding direct-runoff ordinates by the same factor. III. Superposition permits shifted runoff responses from successive effective-rainfall blocks to be added ordinate by ordinate. IV. Base flow should normally be added after the direct-runoff hydrograph is obtained if total flood hydrograph ordinates are required. Which option is correct?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Statement I gives the standard definition of a duration-specific unit hydrograph. Statement II expresses the proportionality component of the linear unit-hydrograph model. Statement III describes superposition and discrete convolution of successive effective-rainfall inputs. Statement IV correctly distinguishes the direct-runoff hydrograph from total storm streamflow containing base flow. Therefore all four statements are correct and Option D is the valid answer.
వివరణ:
Answer Key సమాధానాల పట్టిక
-
Question 1 ప్రశ్న 1Answer: A. It is the direct-runoff hydrograph resulting from one unit depth of effective rainfall uniformly distributed over the catchment at a uniform rate during D hours సమాధానం: A.
-
Question 2 ప్రశ్న 2Answer: A. Because the unit hydrograph transforms only the rainfall remaining after hydrologic abstractions into direct runoff సమాధానం: A.
-
Question 3 ప్రశ్న 3Answer: C. 75 m³/s సమాధానం: C.
-
Question 4 ప్రశ్న 4Answer: A. The catchment response to the same effective-rainfall pulse is assumed to have the same shape and ordinates even if that pulse occurs at a different time, apart from the corresponding time shift సమాధానం: A.
-
Question 5 ప్రశ్న 5Answer: A. Their direct-runoff responses are assumed to have compatible time bases, while their ordinates scale with effective-rainfall depth సమాధానం: A.
-
Question 6 ప్రశ్న 6Answer: A. Obtain the observed streamflow hydrograph → separate base flow → obtain the direct-runoff hydrograph → determine its runoff volume and equivalent effective-rainfall depth → divide direct-runoff ordinates by that depth in unit-depth terms సమాధానం: A.
-
Question 7 ప్రశ్న 7Answer: B. 30 m³/s సమాధానం: B.
-
Question 8 ప్రశ్న 8Answer: B. 11.1 m³/s సమాధానం: B.
-
Question 9 ప్రశ్న 9Answer: C. 0, 45, 135, 90 and 0 m³/s సమాధానం: C.
-
Question 10 ప్రశ్న 10Answer: A. It has the same ordinates and shape but is shifted 4 hours later సమాధానం: A.
-
Question 11 ప్రశ్న 11Answer: A. Runoff responses to separate effective-rainfall pulses may be scaled, shifted to their correct times, and added ordinate by ordinate సమాధానం: A.
-
Question 12 ప్రశ్న 12Answer: C. 70 m³/s సమాధానం: C.
-
Question 13 ప్రశ్న 13Answer: A. The sum of contributions at that time from all earlier effective-rainfall pulses whose shifted unit-hydrograph responses are still active సమాధానం: A.
-
Question 14 ప్రశ్న 14Answer: B. 2 cm సమాధానం: B.
-
Question 15 ప్రశ్న 15Answer: A. Add an appropriate estimated base-flow hydrograph to the direct-runoff ordinates సమాధానం: A.
-
Question 16 ప్రశ్న 16Answer: A. 2 cm సమాధానం: A.
-
Question 17 ప్రశ్న 17Answer: A. The 2-hour unit hydrograph should first be converted to an appropriate 4-hour unit hydrograph before directly applying the 4-hour effective-rainfall blocks సమాధానం: A.
-
Question 18 ప్రశ్న 18Answer: B. 0, 10, 35, 40, 15, 0 m³/s సమాధానం: B.
-
Question 19 ప్రశ్న 19Answer: A. Add n D-hour unit hydrographs successively lagged by D hours and divide the resulting ordinates by n సమాధానం: A.
-
Question 20 ప్రశ్న 20Answer: A. The runoff response produced by a continuous uniform effective-rainfall input of indefinite duration, constructed by summing a sequence of equal-duration unit hydrographs lagged by their unit duration సమాధానం: A.
-
Question 21 ప్రశ్న 21Answer: A. Because the difference corresponds to T/D units of effective-rainfall depth, so multiplication by D/T converts it back to one unit depth సమాధానం: A.
-
Question 22 ప్రశ్న 22Answer: B. 40 m³/s సమాధానం: B.
-
Question 23 ప్రశ్న 23Answer: A. It permits derivation of a unit hydrograph for a desired duration that need not be an integer multiple of the available duration సమాధానం: A.
-
Question 24 ప్రశ్న 24Answer: A. Catchment response becomes strongly nonlinear because runoff-generation or routing characteristics change substantially between storms సమాధానం: A.
-
Question 25 ప్రశ్న 25Answer: D. I, II, III and IV సమాధానం: D.