ANN IRUSA KIDAGE
J173/1343/2017
IRRIGATION ENGINEERING 1 ASSIGNMENT
Basic Terms and Explanations.
Pertaining to Crop and Water
Critical period of crop growth – the sage of growth when plants are more sensitive to
shortage of water.
Root Zone Depth - depth within the soil profile that commodity crop (cc) roots can
effectively extract water and nutrients for growth.
Root zone moisture extraction depth- the depth of soil used by the main body of the
plant roots to obtain most of the stored moisture and plant food under proper irrigation.
Moisture level - the quantity of water contained in the soil (with the soil itself, water, and
air comprising 100%). Generally, soil moisture will range from 10% to 45%, but can be higher
during and after watering.
Pertaining to irrigation on land
Gross commanded area - the total area lying between drainage boundaries which can be
irrigated by a canal system. ... It includes all land on which cultivation is possible, though
all area may not be under cultivation at the time.
Culturable commanded area - part of Gross Command Area, which is fit for cultivating
crops. So, cultivable area excludes forest and barren land from the Gross Command Area.
Intensity of irrigation – the percentage of net irrigated area to the net sown area. It is the
percentage of the culturable commanded area proposed to be irrigated during either a crop season
or during a year. The cropping intensity of irrigation can be more than 100%.
Crop ratio – ratio of proposed areas, to be irrigated in Kharif season to that in the Rabi
season
Overlap allowance - Sometimes, it so happens that crop of previous crop season has not
yet been harvest and the crop of coming season has also been sown. Under such circumstances
irrigation water will have to be provided or some time to both the crops. The time period in days
for which crop of previous season overlaps the new sown crop is known as overlap allowance.
Capacity factor – the ratio of mean supply discharge in a canal during a period to its
design full capacity
Delta – the total depth of the water required by a crop during the entire period the crop is
in the field and is denoted by the symbol ∆
Base period – the time between the first watering of a crop at the time of it’s sowing to
the last watering before harvest.
Duty – the area of land that can be irrigated with unit volume of irrigation water. Duty
represents the irrigating capacity of a unit. It is the relation the between the area of a crop
irrigated and the quantity of irrigation water required during the entire period of the growth of
that crop
Irrigation waterings – the process and cycles in which water is irrigated on crops.
Kor waterings – It is the first watering after sowing of the crop. Depth of kor watering is
always more than the subsequent watering to be given to the crops in its growth or base period