PNS/BAFS/PAES 222:2017

Design of Basin, Border and Furrow Irrigation Systems

PNS/BAFS/PAES 222:2017

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

basin

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.

basin irrigation

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

border irrigation

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

border strip

small parallel channels, made to carry water in order to irrigate the crop

furrows

method of irrigation where water runs through small parallel channels as it moves down the slope of the field

furrow irrigation

small channel along one part of a field that is used for distributing water in surface irrigation

head ditch or supply ditch

application of water by gravity flow to the surface of the field. Either the entire field is flooded (basin irrigation) or the water is fed into small channels (furrows) or strips of land (borders)

surface irrigation system

The following data are required in the selection and design of a surface irrigation system:

Slope, soil type, type of crop, irrigation depth, stream size

Furrow irrigation soil selection criteria

Coarse to moderate textured soils

Border irrigation soil selection criteria

Moderate to fine textured soils

Basin irrigation soil selection criteria

Moderate to fine textured soils

Furrow irrigation crop selection criteria

Row crops ( corn, vegetables, tree, sugarcane)

Border irrigation crop selection criteria

Row/solid-stand crops, annual crops (sugarcane, forage, pasture)

Basin irrigation crop selection criteria

Solid-stand crops (paddy rice and other which can withstand waterlogged conditions)

Furrow irrigation water suuply selection criteria

Low-discharge, long duration, frequent supply

Border irrigation water suuply selection criteria

Moderately high discharge, short duration, infrequent supply

Basin irrigation water suuply selection criteria

High discharge, short duration, infrequent supply

Principal Risk for furrow irrigation

erosion

Principal Risk for border irrigation and basin irrigation

scalding

Furrow irrigation slope selection criteria

0.05 % to 3.0 %

Border irrigation slope selection criteria

2.0% to 5.0%

Basin irrigation slope selection criteria

less than or equal to 0.1%

Water applied to an individual basin and all of that applied water is allowed to infiltrate.

Closed Single Basin

Each basin is irrigated separately by a supply channel running along the boundary with a number of adjacent basins

Multiple/ Sequential Basin

The basin shall be nearly if not completely level to prevent tailwater. A difference of ______ between the highest and lowest elevations may be allowed such that it is less than one-half of the net depth of application.

6 cm to 9 cm

Top width of the basin dike shall be greater than or equal to the height of the dike. The settled height shall be at least equal to either the gross application depth or the design maximum depth of flow plus a freeboard of _____, whichever is greater.

25%

The water surface in the ditch shall be _______ above the ground surface level in the basin depending on the outlet characteristics.

15 cm to 30 cm

The minimum design application efficiency of basin irrigation shall be

70%

The ditches shall be constructed with a ____ grade or less to minimize the number of check structures and labor requirements.

0.10%

– One outlet shall be installed for basin widths of up to ___ and flow rates up to ______

6 m; 0.4 m3/s.

The maximum water flow velocity into the basin shall be less than or equal to ____ to avoid scouring and erosion.

1 m/s

Irrigation water is led directly from the field channel into the basin through siphons, spiles or bundbreaks.

direct method

Irrigation water is supplied to the highest terrace, and then allowed to flow to a lower terrace and so on.

cascade method

This is usually applied to large borders where the end borders are provided with openings to accommodate free flow of water for drainage

Open-end Border System

This is usually applied to small borders where the end borders restrict the further downward flow of water.

Blocked-end Border System

The soil shall have a moderately low to moderately high intake rate which is_______. Coarse sandy soils with extremely high and those with etremely low intake rate shall be avoided.

7.6 mm/hr to 50 mm/hr

On clay soils, the inflow is stopped when the irrigation water covers ____ of the border.

60%

On loamy soils it is stopped when _____ of the border is covered with water.

70 to 80%

On sandy soils the irrigation water must _____ before the flow is stopped.

cover the entire border

The water flows down the slope in small furrows called corrugalions or rills which is used for germinating drill-seeded or broadcasted crops.

corrugation irrigation

This type of furrow irrigation shall increase the length that the water must travel to reach the end of irrigation run thus, reducing the average slope and velocity of the water.

Zigzag Furrow

If the land slope is steeper than _______, furrows shall be set at an angle to the main slope or along the contour to keep furrow slopes within the recommended limits.

0.50%

– If the furrows are not too long, _____ of stream flow shall be adequate for irrigation but the maximum stream size shall largely depend on the furrow slope.

0.5 L/s

Furrow Spacing for Coarse Sand

30

Furrow Spacing for Fine Sand

60

Furrow Spacing for Clay

75-150

It involves irrigating alternate furrows rather than every furrow. Small amounts applied frequently in this way are usually better for the crop than large amounts applied after longer intervals of time.

Alternate Furrow Irrigation

a device with individual scales on the rods to provide data to plot furrow depth

profilometer

Narrow, deep V-shaped furrows shall be made in _____ soils in order to reduce the area through which water percolates.

sandy

Wide, shallow furrows shall be made in ______ soils in order to obtain a large wetted area

clay