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Question 1
ప్రశ్న 1
Which statement best defines a streamflow hydrograph at a specified river section?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
A streamflow hydrograph shows how discharge at a particular river section varies with time. The vertical axis represents discharge, commonly in cubic metres per second, while the horizontal axis represents time. A storm or flood hydrograph therefore displays the catchment's integrated response to rainfall and other hydrologic processes. Its shape reflects runoff generation, catchment storage, routing, interflow and base flow. Therefore Option A is correct.
వివరణ:
Question 2
ప్రశ్న 2
Which description best represents a typical single-storm flood hydrograph?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
A catchment generally begins from some pre-storm streamflow condition. Storm-generated runoff causes discharge to increase along the rising limb. The hydrograph then reaches a crest region containing the maximum discharge. As runoff inputs diminish and catchment storage drains, discharge decreases along the recession limb. Therefore Option A correctly describes the usual form of a single-event flood hydrograph.
వివరణ:
Question 3
ప్రశ్న 3
In conventional storm-hydrograph analysis, which relationship is most appropriate?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The measured discharge during a storm normally contains both relatively rapid storm response and slower background flow. The rapid portion is commonly classified as direct runoff after an appropriate base-flow separation. Base flow is supplied mainly from groundwater and other relatively slow natural storage. Thus the observed storm hydrograph can conceptually be decomposed into direct runoff plus base flow. Therefore Option A is correct.
వివరణ:
Question 4
ప్రశ్న 4
What does the rising limb of a flood hydrograph primarily indicate?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The rising limb begins when discharge increases appreciably in response to the storm. Runoff generated from different portions of the catchment reaches the stream network and outlet after different travel times. As these contributions accumulate, stream discharge rises. The steepness of the limb depends on rainfall characteristics and catchment properties such as slope, drainage efficiency, storage and imperviousness. Therefore Option A is correct.
వివరణ:
Question 5
ప్రశ్న 5
Which statement best describes the crest segment of a flood hydrograph?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The crest segment is the upper portion of the flood hydrograph around its highest discharge. The maximum ordinate within this region is the peak discharge. The crest may be sharp when runoff is highly synchronized or broader when rainfall duration and basin storage spread the response through time. It is not required to be horizontal or to have a fixed duration. Therefore Option A is correct.
వివరణ:
Question 6
ప్రశ్న 6
What is the principal hydrologic interpretation of the recession limb after the main storm input has diminished?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The recession limb represents declining streamflow after the major storm-generated inflow has passed. Catchment and channel storages continue to release water even after effective rainfall decreases or stops. This produces a gradual rather than instantaneous return toward lower flow. Recession behaviour therefore contains information about catchment storage and drainage characteristics. Hence Option A is correct.
వివరణ:
Question 7
ప్రశ్న 7
For a particular flood hydrograph, direct runoff begins at 02:00 and peak discharge occurs at 08:00. If time to peak is defined from the beginning of the rising limb to the peak, what is the time to peak?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Time to peak is explicitly defined in the question from the start of the direct-runoff rise to the hydrograph peak. The rising limb begins at 02:00. Peak discharge occurs at 08:00. The elapsed time is therefore 08:00 minus 02:00, which equals 6 hours. Hence Option B is correct.
వివరణ:
Question 8
ప్రశ్న 8
Direct runoff from a storm begins at elapsed time 3 h and becomes negligible at elapsed time 18 h. What is the base time of the direct-runoff hydrograph?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The time base is the total duration from the beginning to the end of direct runoff. Direct runoff begins at 3 hours and ends at 18 hours. The time base is therefore 18 - 3 = 15 hours. This quantity should not be confused with agricultural terminology such as crop base period. Therefore Option B is correct.
వివరణ:
Question 9
ప్రశ్న 9
The centroid of effective rainfall for a storm occurs at elapsed time 4.5 h, while the direct-runoff hydrograph reaches its peak at 9.0 h. If basin lag is defined as the time from the centroid of effective rainfall to the runoff peak, what is the lag?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The definition of basin lag is stated explicitly in the question. The effective-rainfall centroid occurs at 4.5 hours. The runoff peak occurs at 9.0 hours. Their time difference is 9.0 - 4.5 = 4.5 hours. Therefore the basin lag is 4.5 hours and Option B is correct.
వివరణ:
Question 10
ప్రశ్న 10
For a storm, the direct-runoff hydrograph starts at 2 h, the centroid of effective rainfall occurs at 4 h, and the hydrograph peak occurs at 8 h. Using time to peak from the start of direct runoff and lag from the effective-rainfall centroid to the peak, what are the two values respectively?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Time to peak is measured from the beginning of direct runoff at 2 hours to the peak at 8 hours. It is therefore 8 - 2 = 6 hours. Lag under the definition supplied in the question is measured from the effective-rainfall centroid at 4 hours to the peak at 8 hours. It is therefore 4 hours. Hence the correct pair is 6 h and 4 h, making Option B correct.
వివరణ:
Question 11
ప్రశ్న 11
Why can stream discharge continue to increase for some time after rainfall over the catchment has stopped?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Rainfall does not reach the catchment outlet instantaneously as runoff. Water generated in remote subareas requires finite time to move across slopes and through the channel network. Catchment and channel storage can also delay the outflow response. Thus discharge at the outlet can continue increasing after local or basin rainfall has ceased. Therefore Option A is correct.
వివరణ:
Question 12
ప్రశ్న 12
Which statement about base flow during a flood hydrograph is most appropriate?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Base flow is primarily sustained by groundwater discharge and other slowly draining natural storage. It commonly exists before the storm and continues beneath the storm hydrograph. Its variation is usually slower than that of direct storm runoff. Base flow therefore does not need to become zero when a flood occurs. Hence Option A is correct.
వివరణ:
Question 13
ప్రశ్న 13
At one instant during a storm, observed stream discharge is 120 m³/s and the estimated base-flow contribution is 25 m³/s. What is the corresponding direct-runoff discharge?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
At any instant, the separated direct-runoff ordinate is obtained by subtracting estimated base flow from observed total streamflow. Thus the direct-runoff discharge is 120 - 25 = 95 m³/s. The calculation depends on the adopted base-flow separation estimate. The total streamflow itself remains the actually observed quantity. Therefore Option B is correct.
వివరణ:
Question 14
ప్రశ్న 14
Why should a base-flow separation line beneath a storm hydrograph generally be regarded as an estimate rather than an exactly observed physical boundary?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
A stream gauge measures the combined discharge passing the section. It does not directly identify which water particles originated as surface runoff, interflow or groundwater. Hydrologists therefore apply conceptual or graphical separation procedures to estimate base flow beneath a storm hydrograph. Different reasonable procedures can yield somewhat different direct-runoff volumes. Therefore Option A is correct.
వివరణ:
Question 15
ప్రశ్న 15
In the simple straight-line method of base-flow separation, which assumption is commonly made?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The straight-line approach is one of the simplest graphical separation techniques. In its basic form, base flow is assumed approximately constant beneath the direct-runoff event. A line is drawn from the beginning of the hydrograph rise toward a suitable point on the recession limb. The resulting area above the separation line is interpreted as direct runoff. Therefore Option A is correct.
వివరణ:
Question 16
ప్రశ్న 16
A storm hydrograph has total-discharge ordinates of 20, 60, 100, 60 and 20 m³/s at times 0, 2, 4, 6 and 8 h respectively. If base flow is assumed constant at 20 m³/s, what direct-runoff volume is obtained using trapezoidal integration?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Subtracting the constant base flow gives direct-runoff ordinates of 0, 40, 80, 40 and 0 m³/s. With a 2-hour spacing, trapezoidal integration gives an area of 320 m³/s-hours. Converting hours to seconds gives 320 × 3600 = 1,152,000 m³. This equals 1.152 million m³. Therefore Option B is correct.
వివరణ:
Question 17
ప్రశ్న 17
A direct-runoff hydrograph has ordinates 0, 40, 80, 40 and 0 m³/s at 2-hour intervals over a 16 km² catchment. Using trapezoidal integration, what is the equivalent direct-runoff depth?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Trapezoidal integration of the stated ordinates gives a direct-runoff volume of 1,152,000 m³. The catchment area is 16 km², or 16,000,000 m². Dividing volume by area gives 0.072 m of runoff depth. Converting metres to millimetres gives 72 mm. Therefore Option C is correct.
వివరణ:
Question 18
ప్రశ్న 18
An idealized triangular direct-runoff hydrograph has a peak discharge of 150 m³/s and a base time of 10 h. What is its direct-runoff volume?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The area under a triangular discharge-time hydrograph is one-half times its base duration times its peak ordinate. The base time is 10 h, or 36,000 s. Thus the volume is 0.5 × 150 × 36,000 m³. This equals 2,700,000 m³, or 2.70 million m³. Therefore Option B is correct.
వివరణ:
Question 19
ప్రశ్న 19
Why does the area under a discharge-versus-time hydrograph represent a water volume?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Discharge is a volumetric flow rate, commonly expressed in cubic metres per second. Multiplying a constant discharge by a time interval produces a volume. For a varying discharge, the same operation is performed through integration with respect to time. Numerically, discrete hydrograph ordinates can be integrated using methods such as the trapezoidal rule. Therefore Option A is correct.
వివరణ:
Question 20
ప్రశ్న 20
An idealized recession is represented by q(t) = q0 e^(-kt), where q0 = 80 m³/s and k = 0.15 h^-1. What discharge is predicted 6 h later?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Substitution gives q = 80e^(-0.15×6). The exponent is -0.90. The value of e^-0.90 is approximately 0.4066. Therefore q is approximately 80 × 0.4066 = 32.5 m³/s. Hence Option B is correct.
వివరణ:
Question 21
ప్రశ్న 21
For the same intense storm, how would extensive urbanization with directly connected impervious surfaces generally alter a small catchment flood hydrograph compared with a more permeable undeveloped condition?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Impervious surfaces reduce infiltration and convert a greater fraction of storm rainfall into rapid surface runoff. Storm sewers and paved drainage paths can also decrease travel time to the channel. Contributions from different parts of the urban catchment therefore tend to arrive more rapidly. The result is commonly a sharper hydrograph with a higher and earlier peak for a comparable storm. Therefore Option A is correct.
వివరణ:
Question 22
ప్రశ్న 22
Two otherwise similar catchments receive the same storm, but one is already very wet before rainfall begins. What hydrograph response is generally more likely from the wetter catchment?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
A wet catchment has already used a substantial part of its soil-moisture and subsurface storage capacity. Additional rainfall can therefore generate runoff more efficiently. Saturated or nearly saturated areas may also expand during the event. These effects can increase direct-runoff volume and produce a stronger flood response. Therefore Option A is correct.
వివరణ:
Question 23
ప్రశ్న 23
Which change would generally tend to attenuate and delay a flood hydrograph peak, other factors being comparable?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Temporary storage retains part of the inflowing runoff and releases it over a longer period. This delays the arrival of some water at the downstream outlet. The spreading of runoff through time commonly reduces the maximum discharge while lengthening the response. Such storage effects are fundamental to flood attenuation and routing. Therefore Option A is correct.
వివరణ:
Question 24
ప్రశ్న 24
A recorded flood hydrograph contains two distinct peaks during a prolonged storm. Which interpretation is most reasonable?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Real storms can contain multiple periods of intense rainfall. Runoff from separate rainfall bursts can reach the outlet at different times and produce distinct rises. Spatially variable rainfall and different travel times among subcatchments can also generate multiple peaks. A second peak therefore does not by itself demonstrate measurement error. Hence Option A is correct.
వివరణ:
Question 25
ప్రశ్న 25
Consider the following statements about flood hydrographs: I. The rising limb represents increasing stream discharge associated with the arrival of storm runoff. II. Base time is the duration from the beginning to the end of direct runoff. III. Direct-runoff hydrograph ordinates are obtained by subtracting estimated base flow from total stormflow ordinates. IV. The recession limb reflects drainage of catchment and channel storage after major storm input diminishes. Which option is correct?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Statement I correctly describes the increasing-discharge portion of a storm hydrograph. Statement II gives the conventional meaning of the direct-runoff time base. Statement III correctly describes how the direct-runoff hydrograph is obtained once a base-flow separation has been adopted. Statement IV correctly interprets the falling or recession limb as progressive drainage and routing of stored water. Therefore all four statements are correct and Option D is the valid answer.
వివరణ:
Answer Key సమాధానాల పట్టిక
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Question 1 ప్రశ్న 1Answer: A. A plot of stream discharge against time సమాధానం: A.
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Question 2 ప్రశ్న 2Answer: A. Discharge rises above pre-storm flow, reaches a crest or peak, and subsequently recedes toward lower flow సమాధానం: A.
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Question 3 ప్రశ్న 3Answer: A. Observed streamflow = direct runoff + base flow సమాధానం: A.
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Question 4 ప్రశ్న 4Answer: A. Increasing discharge as storm runoff from progressively contributing parts of the catchment reaches the outlet సమాధానం: A.
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Question 5 ప్రశ్న 5Answer: A. It is the region around the maximum discharge, including the hydrograph peak సమాధానం: A.
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Question 6 ప్రశ్న 6Answer: A. Stored water in channels, hillslopes, soils and subsurface pathways is progressively draining from the catchment సమాధానం: A.
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Question 7 ప్రశ్న 7Answer: B. 6 h సమాధానం: B.
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Question 8 ప్రశ్న 8Answer: B. 15 h సమాధానం: B.
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Question 9 ప్రశ్న 9Answer: B. 4.5 h సమాధానం: B.
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Question 10 ప్రశ్న 10Answer: B. 6 h and 4 h సమాధానం: B.
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Question 11 ప్రశ్న 11Answer: A. Runoff generated in distant portions of the catchment can still be travelling through hillslopes and channels toward the outlet సమాధానం: A.
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Question 12 ప్రశ్న 12Answer: A. It is the relatively slow-flow component associated mainly with groundwater and other delayed storage and need not become zero during a flood సమాధానం: A.
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Question 13 ప్రశ్న 13Answer: B. 95 m³/s సమాధానం: B.
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Question 14 ప్రశ్న 14Answer: A. Only total streamflow is directly observed, and the division between rapidly responding flow and slower base flow requires assumptions or analytical methods సమాధానం: A.
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Question 15 ప్రశ్న 15Answer: A. Base flow is represented approximately by a straight, often horizontal, line from the start of direct runoff until it meets the recession side of the hydrograph సమాధానం: A.
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Question 16 ప్రశ్న 16Answer: B. 1.152 million m³ సమాధానం: B.
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Question 17 ప్రశ్న 17Answer: C. 72 mm సమాధానం: C.
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Question 18 ప్రశ్న 18Answer: B. 2.70 million m³ సమాధానం: B.
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Question 19 ప్రశ్న 19Answer: A. Because discharge has units of volume per unit time, so integrating it with respect to time gives volume సమాధానం: A.
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Question 20 ప్రశ్న 20Answer: B. 32.5 m³/s సమాధానం: B.
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Question 21 ప్రశ్న 21Answer: A. It generally produces a steeper rising limb, shorter response time and higher peak discharge సమాధానం: A.
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Question 22 ప్రశ్న 22Answer: A. Greater direct-runoff volume and potentially a higher, faster flood response because less additional storage is available సమాధానం: A.
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Question 23 ప్రశ్న 23Answer: A. Greater temporary storage in wetlands, lakes, floodplains or other detention features సమాధానం: A.
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Question 24 ప్రశ్న 24Answer: A. Separate rainfall bursts or differently timed runoff contributions can produce a multi-peaked hydrograph సమాధానం: A.
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Question 25 ప్రశ్న 25Answer: D. I, II, III and IV సమాధానం: D.