General Irrigation Terminologies

Question 1

areas open for public entry such as golf course, public and private parks, playgrounds, schoolyards, and playing fields, residential landscapes and industrial park landscapes

Answer 1

access areas

Question 2

volume of water stored in reservior between the minimum water level and normal water level

Answer 2

active storage

Question 3

rate of evapotranspiration equal to or smaller than predicted crop evapotranspiration as affected by the level of available soil water, salinity, field size or other causes.

Answer 3

actual crop evapotranspiration

Question 4

rise in maximum flood level from the original unobstructed flood level which result after an obstruction to the flow such as a dam, has been introduced

Answer 4

afflux elevation

Question 5

overgrowths of algae in water producing dangerous toxins in fresh or marine
water

Answer 5

algal bloom

Question 6

ratio of the average depth of irrigation water infiltrated and stored in the root zone to the average depth of irrigation water applied

Answer 6

application efficiency

Question 7

geologic formation which contains water and transmits it at a rate sufficient to
be economically developed for pumping artificially developed well

Answer 7

acquifer

Question 8

cross-sectional area of the flow which is measured perpendicular to the direction
of flow

Answer 8

area

Question 9

field that is level in all directions, encompassed by a dike to prevent runoff, and
provides an undirected flow of water onto the field

Answer 9

basin

Question 10

type of surface irrigation where water is applied to the basin through a gap in the perimeter dike or adjacent ditch; water is retained until it infiltrates into the soil or the excess is drained off

Answer 10

basin irrigation

Question 11

maximum average contact pressure between the foundation and the soil which
should not produce shear failure in the soil

Answer 11

bearing capacity

Question 12

method of irrigation which makes use of parallel border strips where the water
flows down the slope at a nearly uniform depth

Answer 12

border irrigation

Question 13

area of land bounded by two border ridges or dikes that guide the irrigation stream from the inlet point of application to the ends of the strip

Answer 13

border strip

Question 14

inclination or elevation drop per unit length of the channel bottom

Answer 14

channel bed slope

Question 15

groundwater that is confined by relatively impermeable layer

Answer 15

confined aquifer

Question 16

introduction of substances not found in the natural composition of water that make the water less desirable or unfit for intended use

Answer 16

contamination

Question 17

ratio between water received at the inlet for a block of fields to that released at the project’s headwork

Answer 17

conveyance efficiency

Question 18

loss of water from a channel during transport due to seepage and percolation

Answer 18

conveyance loss

Question 19

depth of water flow where the energy content is at minimum hence, no other backwater forces are involved

Answer 19

critical depth

Question 20

ratio of actual crop evapotranspiration to its potential evapotranspiration rate is

Answer 20

crop coefficient

Question 21

rate of evapotranspiration of a disease-free crop growing in a large field (one or
more ha) under optimal soil conditions, including sufficient water and fertilizer
and achieving full production potential of that crop under the given growing
environment; includes water loss through transpiration by the vegetation, and
vaporation from the soil surface and wet leaves

Answer 21

crop evapotranspiration

Question 22

sequence of different crops grown in regular order on any particular field or
fields

Answer 22

cropping pattern

Question 23

amount of water used in producing crops which is the sum of evapotranspiration or consumptive use plus seepage and percolation losses

Answer 23

crop water requirements

Question 24

any barrier constructed to store water

Answer 24

dam

Question 25

vertical distance from lowest point of the ground line to the dam crest

Answer 25

dam height

Question 26

volume below the intake structure; sediment volume based on 25 years of
accumulation in the reservoir

Answer 26

dead storage