CHAPTER 6

Question 1

It is the process and pathways through which excess water becomes streamflow’; excess water is that part of the total rainfall amount which runs off the land surface, and that which drains from the soil and is not consumed in evapotranspiration.

Answer 1

Runoff

Question 2

It is the pathway in which rain falls directly into the stream chennel.

Answer 2

Channel Interception

Question 3

It is the pathway in which excess water flows over the soil surface.

Answer 3

Surface Runoff or Overland Water Flow

Question 4

It is a tabular or graphical representation of streamflow discharge against time.

Answer 4

Streamflow Hydrograph

Question 5

Precipitation must satisfy the demands of evaporation, interception, infiltration, surface storage, surface detention, and channel detention before runoff can occur.

Answer 5

Runoff Process

Question 6

Give the factors affecting runoff:

Answer 6

• Rainfall
• Watershed
• Control section

Question 7

It is the duration, intensity and areal distribution.

Answer 7

Rainfall

Question 8

It is the size, shape, orientation, topography, geology and surface culture.

Answer 8

Watershed

Question 9

TRUE OR FALSE:

Intensity influences total runoff.

Answer 9

False

DURATION influences total runoff.

Question 10

TRUE OR FALSE:

Intensity influences rate and volume of runoff.

Answer 10

True

Question 11

TRUE OR FALSE:

An intense storm decreases infiltration rate because of its destructive action on soil structure at the surface.

Answer 11

True

Question 12

TRUE OR FALSE:

Duration of rainfall influences rate and volume of runoff.

Answer 12

False

AREAL DISTRIBUTION of rainfall influences rate and volume of runoff.

Question 13

TRUE OR FALSE:

Runoff is decreased for storms moving upstream.

Answer 13

True

Question 14

TRUE OR FALSE:

Flat areas have low runoff.

Answer 14

True

Question 15

TRUE OR FALSE:

Structures, soil materials and vegetation affect infiltration rate hence, runoff.

Answer 15

False

GEOLOGY, soil materials and vegetation affect infiltration rate hence, runoff.

Question 16

TRUE OR FALSE:

Structures such as dams affect runoff rate.

Answer 16

True

Question 17

Measurement of streamflow:

Answer 17

• Stage
• Rating curve

Question 18

It is the height of water in a stream.

Answer 18

Stage

Question 19

It is the graph of the stage and streamflow discharge.

Answer 19

Rating Curve

Question 20

It is the section of stream for which a rating curve will be developed.

Answer 20

Control Section

Question 21

Give the measurement of Stage:

Answer 21

• Staff Gauge
• Continuous water level recorder

Question 22

It is a graduated staff used for the visual observation of water level.

Answer 22

Staff Gauge

Question 23

Give the measurement of velocity:

Answer 23

• Float Method
• Current meter method
• Weirs
• Flumes

Question 24

It is the time required for a floating object that is tossed into the stream to travel a specified distance on the surface of the water is observed.

Answer 24

Float Method

Question 25

It is when the average velocity is multiplied by cross-sectional area of the stream to estimate streamflow discharge.

Answer 25

Float Method

Question 26

It is an instrument in which a wheel is made to rotate about its axis by the force of current.

Answer 26

Current Meter Method

Question 27

It is the speed of the rotation depends upon the velocity of water.

Answer 27

Current Meter Method

Question 28

The general relationship between the numbers of revolutions and the velocity of streamflow is V = a + bN

Answer 28

Current meter method

Question 29

The ___________ is estimated by measuring the average velocity of each section with the current meter.

Answer 29

Streamflow Velocity

Question 30

It is the barriers placed across the stream over which water flows; provides a simple and accurate means of measuring water.

Answer 30

Weirs

Question 31

It is the height of water above the crest.

Answer 31

Head

Question 32

It is the edge or surface over which the water flows.

Answer 32

Crest

Question 33

It has a blade with a sharp upstream edge, so that the passing water touches only a thin edge and clear the rest of the crest.

Answer 33

Sharp-crested

Question 34

It has a flat or broad surface over which the water flows.

Answer 34

Broad-crested

Question 35

It is artificial open channels built to contain streamflows within designed cross-sectional areas and legnth.

Answer 35

Flumes

Question 36

Types of flumes:

Answer 36

- Parshall Flume - Trapezoidal Flume