Irrigation & Drainage

Question 1

The quantity of water, exclusive of precipitation required to maintain desired soil moisture and salinity level during the crop season

Answer 1

Irrigation Water Requirement

Question 2

Methods of irrigation water application wherein the soil is moistened in much the same way as rain

Answer 2

Overhead irrigation

Question 3

Sum of evapotranspiration and percolation losses

Answer 3

Crop Water Requirement

Question 4

In-line structure with a geometrically specified constriction built in an open channel such that the center line coincides with the center line of the channel in which the flow is to be measured

Answer 4

Flume

Question 5

A device with individual scales on the rods to provide data to plot furrow depth as a function of the lateral distance where data can then be numerically integrated to develop geometric relationships such as area vs depth, wetted perimeter versus depth and top-width vs depth

Answer 5

Profilometer

Question 6

Farm turnout requirements plus conveyance losses in the main canal and lateral up to the farm turnout

Answer 6

Diversion requirement

Question 7

This system is used in rolling topography where drainage is necessary only in small valleys

Answer 7

Natural system

Question 8

Recommended slope for basin irrigation method

Answer 8

Less than or equal to 0.1%

Question 9

Recommended slope for border irrigation method

Answer 9

2 - 5 %

Question 10

Recommended slope for furrow irrigation method

Answer 10

0.05 - 3%

Question 11

Maximum sprinkler spacing, in rectangular pattern if average wind speed is above 15 kph

Answer 11

30 % between sprinklers, 50% between laterals

Question 12

An overflow structure built perpendicular to an open channel axis to measure the rate of flow of water

Answer 12

Weir

Question 13

Application of water by gravity flow to the surface of the field

Answer 13

Surface irrigation

Question 14

It is the ratio between the gross amount of irrigation water and the net requirement of the crop

Answer 14

Water application efficiency

Question 15

Structures which raises the water flowing through rivers, creeks or streams to a desired height. The water is then diverted to conveyance canals to supply the requirements of the areas served

Answer 15

Diversion dam

Question 16

The power theoretically required to lift a given quantity of water each second to specified height

Answer 16

Water horsepower

Question 17

The soil type largely influences the width of bed to be used. The furrows drain to collection ditches

Answer 17

Bending system

Question 18

This system is adapted to areas that have depressions which are too deep or too large to fill by land leveling

Answer 18

Random ditch system

Question 19

Expresses the relationship between speed in rpm, discharge in gpm, and head in feet

Answer 19

Specific speed

Question 20

These structures are usually constructed or placed along supplementary farm ditch at head of the internal farm ditch to control and regulate water flow serving the farm or group of forms

Answer 20

Off-takes

Question 21

The ratio of the dry weight of the soil to the volume of soil particles alone

Answer 21

Particle density

Question 22

This is suitable on flat, poorly drained soils that have numerous shallow depressions, in general, the ditches are 185m to a max. to 370 m apart

Answer 22

Diversion or parallel ditch system

Question 23

Maximum sprinkler spacing, in square pattern if average wind speed is 13-19 kph

Answer 23

45%

Question 24

Maximum sprinkler spacing, in rectangular pattern if average wind speed is up to 10 kph

Answer 24

40% between sprinklers, 65% between laterals

Question 25

Maximum sprinkler spacing, in rectangular pattern if average wind speed is 10-15 kph

Answer 25

40% between sprinklers, 60% between laterals

Question 26

It is used if the entire area is to be drained and is usually more economic. Laterals enter the submain from one side only to minimize the double drainage that occurs near the submain.

Answer 26

Gridiron layout

Question 27

That portion of the available moisture that is most easily extracted by plants; approximately 75% of the available moisture

Answer 27

Readily available moisture (RAM)