Test 6 - Runoff Process and Factors Affecting Runoff

Question 1 ప్రశ్న 1

In catchment hydrology, what is a watershed or drainage basin?

A The land area from which water drains toward a common outlet B Only the channel occupied by the main river C The saturated groundwater zone below every catchment D The portion of a basin that never contributes water to a stream

Question 2 ప్రశ్న 2

Which statement best describes surface runoff or overland flow?

A Water flowing over the land surface toward channels after relevant surface abstractions and infiltration limitations are satisfied B Water moving only through deep saturated aquifers C Water vapour returning from vegetation to the atmosphere D Water permanently retained in soil pores

Question 3 ప్రశ్న 3

What is interflow or subsurface storm flow?

A Relatively shallow lateral movement of infiltrated storm water through the subsurface toward a stream B Only deep groundwater flow through a regional confined aquifer C Direct rainfall falling onto a river channel D Surface water stored permanently in a lake

Question 4 ప్రశ్న 4

Which description best represents base flow in a stream?

A The relatively slow streamflow contribution supplied mainly by groundwater discharge B The rainfall intensity above infiltration capacity C Only water flowing across pavement during a storm D The maximum instantaneous flood discharge

Question 5 ప్రశ్న 5

In conventional storm-hydrograph analysis, what is meant by direct runoff?

A The storm-response portion of streamflow above the separated base-flow contribution, potentially including overland flow and prompt interflow B Only groundwater flow occurring before the storm C Only rainfall falling directly onto the stream surface D Total streamflow including all pre-existing base flow

Question 6 ప్రశ్న 6

Which condition most directly produces infiltration-excess overland flow?

A Rainfall intensity exceeds the soil infiltration capacity for a sufficient period B Rainfall intensity remains below infiltration capacity throughout the event C Groundwater levels decline far below the land surface D Evapotranspiration exceeds precipitation during a dry season

Question 7 ప్రశ్న 7

Which situation is most characteristic of saturation-excess runoff?

A Rain falls on an area whose soil profile or near-surface zone is already saturated, causing additional water to become surface runoff B Rainfall is always less than infiltration capacity over a deep dry soil C The water table falls rapidly during a storm D All rainfall evaporates before reaching the ground

Question 8 ప్రశ్న 8

Two otherwise identical catchments receive the same storm, but Catchment A was very wet before the storm whereas Catchment B was relatively dry. Which response is generally more likely?

A Catchment A will generally have greater and more rapid runoff because less additional soil-water storage is available B Catchment B must always generate more runoff because dry soil contains less water C Antecedent moisture cannot influence runoff D Both hydrographs must be identical because rainfall is identical

Question 9 ప్రశ్న 9

For a permeable catchment, what is the likely effect of increasing rainfall intensity from well below to well above the prevailing infiltration capacity, with other factors unchanged?

A The potential for infiltration-excess surface runoff increases B Surface runoff must decrease to zero C The soil infiltration capacity necessarily becomes infinite D Base flow instantly becomes the entire streamflow

Question 10 ప్రశ్న 10

A uniform storm has rainfall intensity 45 mm/h for 2 hours over a soil whose infiltration capacity is assumed constant at 15 mm/h. If all rainfall above infiltration capacity becomes runoff and other abstractions are neglected, what is the runoff depth?

A 30 mm B 45 mm C 60 mm D 90 mm

Question 11 ప్రశ్న 11

For storms of similar average intensity, why can increasing rainfall duration substantially increase runoff from a catchment?

A Longer rainfall can progressively satisfy interception, depression and soil-moisture deficits and allow a greater fraction of later rainfall to become runoff B Longer rainfall always increases infiltration capacity indefinitely C Storm duration has no connection with runoff volume D A long storm necessarily produces less runoff than every short storm

Question 12 ప్రశ్న 12

Why does the spatial distribution of rainfall over a watershed matter for outlet runoff?

A Rain falling over hydrologically active portions of the watershed may produce a different runoff volume and timing than the same basin-average depth distributed differently B Only basin-average rainfall depth matters under every circumstance C Rainfall location matters only for groundwater and never for surface flow D Rain over the upper watershed can never reach the outlet

Question 13 ప్రశ్న 13

For an elongated basin, why can the direction of storm movement affect the flood peak at the outlet?

A Storm movement can alter the timing with which runoff contributions from different subareas arrive and may increase or decrease their synchronization B Storm direction changes the basin area C Storm movement has no possible effect on hydrograph timing D A moving storm always produces zero runoff

Question 14 ప్రశ్న 14

For two otherwise similar watersheds, what is the usual effect of a steeper land and channel slope on the runoff hydrograph?

A It generally promotes faster drainage and a shorter, sharper response with potentially higher peak discharge B It necessarily eliminates surface runoff C It always increases infiltration enough to remove the flood peak D It makes travel time independent of channel velocity

Question 15 ప్రశ్న 15

What does a relatively high drainage density generally imply about catchment runoff response, other factors being comparable?

A A more closely spaced channel network can collect and route water rapidly, tending toward a faster basin response B The catchment contains no stream channels C Runoff must remain entirely underground D Travel distance to a channel must always increase

Question 16 ప్రశ్న 16

Two basins have equal area, similar slopes, land use and rainfall, but one is compact and the other strongly elongated. Which hydrograph tendency is generally expected?

A The compact basin may produce a higher and earlier peak because travel times from different areas are more nearly similar B The elongated basin must always have the higher peak C Basin shape cannot affect hydrograph timing D The compact basin can produce runoff only from groundwater

Question 17 ప్రశ్న 17

For a given spatially uniform rainfall-excess depth, what is the most direct effect of increasing catchment area?

A The total runoff volume increases in proportion to contributing area, although hydrograph timing also depends on basin size and routing B Runoff volume necessarily decreases in direct proportion to area C Catchment area affects neither volume nor hydrograph response D Larger catchments cannot generate direct runoff

Question 18 ప్రశ్న 18

Which soil condition generally promotes greater storm runoff, other factors being comparable?

A Low-permeability or compacted soil with limited infiltration B Highly permeable soil with substantial available storage C Deep coarse soil containing effective macropores and low antecedent moisture D A permeable soil profile that readily accepts rainfall

Question 19 ప్రశ్న 19

How does healthy vegetation generally influence storm runoff compared with severely disturbed bare soil, assuming other factors are comparable?

A Vegetation can increase interception and surface roughness and improve infiltration, tending to reduce and delay rapid surface runoff B Vegetation necessarily increases runoff coefficient to one C Vegetation eliminates infiltration by sealing the soil D Vegetation has no influence on runoff timing or losses

Question 20 ప్రశ్న 20

What is the general hydrologic effect of replacing a large fraction of a natural catchment with roads, roofs and other directly connected impervious surfaces?

A Reduced infiltration and storage opportunity, with greater and faster storm runoff and commonly a higher peak discharge B Increased infiltration through the pavement and lower runoff C Elimination of all drainage to streams D No effect on runoff because catchment area is unchanged

Question 21 ప్రశ్న 21

How do lakes, wetlands, ponds and substantial depression storage within a watershed generally affect a flood hydrograph?

A They can temporarily store runoff, delay its release and attenuate the downstream peak B They always increase the peak discharge instantaneously C They remove all water permanently from the hydrologic cycle D They have no effect on runoff timing

Question 22 ప్రశ్న 22

A storm produces 100 mm of rainfall over a basin and the resulting direct-runoff depth is 35 mm. What is the event runoff coefficient defined as direct-runoff depth divided by rainfall depth?

A 0.25 B 0.35 C 0.65 D 2.86

Question 23 ప్రశ్న 23

A 40 km² watershed produces an event runoff depth of 25 mm. What runoff volume leaves the watershed, assuming the stated depth is spatially averaged over the entire area?

A 0.10 million m³ B 0.40 million m³ C 1.00 million m³ D 10.0 million m³

Question 24 ప్రశ్న 24

During a storm, total streamflow volume measured at a catchment outlet is 1.20 million m³. Base-flow analysis indicates that 0.40 million m³ of this volume was groundwater-derived base flow. If catchment area is 20 km², what is the direct-runoff depth?

A 20 mm B 40 mm C 60 mm D 80 mm

Question 25 ప్రశ్న 25

A 25 km² watershed contains a total mapped stream-channel length of 75 km. What is its drainage density?

A 0.33 km/km² B 1.0 km/km² C 3.0 km/km² D 1875 km/km²

Question 26 ప్రశ్న 26

Consider the following statements about runoff response: I. Wet antecedent soil conditions generally favour greater storm runoff than dry conditions. II. Increased imperviousness generally reduces infiltration opportunity and accelerates runoff. III. High drainage density can contribute to a relatively rapid catchment response. IV. Base flow generally varies more slowly than surface runoff during an individual storm. Which option is correct?

A I and II only B I, II and III only C II, III and IV only D I, II, III and IV

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