160
M. N. Yahya et al.
under irrigation, which has become a norm in most countries (Miao et al. 2018).
Water flow rate should be large enough to cover entire basin but not too much to over
saturate the basin’s soil root zone and to cause water spill over the basin’s dike. The
basin method is usually practiced in the irrigation of rice and fodder crops. Some
vegetables like onions are also irrigated using the basin method (Kumar and Vishal
Kumar 2012).
16.2.2 Border Irrigation Method
The border method can be regarded as an optimized basin irrigation method. With the
introduction of slope, a specific shape, and free draining condition at the lower end,
the border irrigation method is more efficient, and inflow has a control and direction
(Bjorneberg 2013). In the border method, the land is divided into a series of strips.
The strips are about 3–30 m wide and 100–800 m long, separated by low levees (or
border or dikes). These strips have uniform slope (less than 0.5%) along the direction
of flow, but there is no cross-slope. Sloping border are suitable for most crops except
those that need prolonged pounding. Therefore, when the water is applied, it flows
over the entire width as it moves down the slope along the longitudinal direction.
Water is supplied to each strip from a ditch made of earth (or concrete). Water from
the earth ditch is usually supplied to the strip by opening a path in the ditch bank.
For concrete ditches, water is supplied to the strip using a gated openings or siphons
made from suitable materials (e.g. plastic pipes) (Kumar and Vishal Kumar 2012).
For groundwater sources, underground concrete pipes are used instead of supply
ditches. As the water is discharged, it flows along the strip towards the lower end
in the form of sheet. It is confined between levees. It infiltrates the soil as it flows.
When the flow approaches the lower end, the supply to the strip is stopped. On a
relatively leveled field, the strips are laid along the general slope of the field. In this
case, the strips are straight and parallel to one another. On a relatively steep field, the
strips are aligned along the contours, with their longer sides parallel to the contour.
In other case, the strips are curved, these strips are known as contour strips (Zerihun
et al. 2013).
In border method, the precision of the field topography is critical, although the
extended length of strips allows the use of machineries for better leveling.
Border methods are grouped into three major categories: (fixed flow, cut back,
and tail water reuse) depending on the management strategy adopted.
Generally, field efficiency ranges from good to excellent depending on the design
and installation of the border strips and good water management. With a slope range
of 0.001–0.002, water efficiency of 70–75% can be achieved on silty clay to clay
soil with water application depth of 75–100 mm. For higher efficiency, stream size
and flow must be controlled to match the moisture depletion rate of the soil to obtain
approximately corresponding infiltration rate at both upper and lower ends (Arora
2014).
M. N. Yahya et al.
under irrigation, which has become a norm in most countries (Miao et al. 2018).
Water flow rate should be large enough to cover entire basin but not too much to over
saturate the basin’s soil root zone and to cause water spill over the basin’s dike. The
basin method is usually practiced in the irrigation of rice and fodder crops. Some
vegetables like onions are also irrigated using the basin method (Kumar and Vishal
Kumar 2012).
16.2.2 Border Irrigation Method
The border method can be regarded as an optimized basin irrigation method. With the
introduction of slope, a specific shape, and free draining condition at the lower end,
the border irrigation method is more efficient, and inflow has a control and direction
(Bjorneberg 2013). In the border method, the land is divided into a series of strips.
The strips are about 3–30 m wide and 100–800 m long, separated by low levees (or
border or dikes). These strips have uniform slope (less than 0.5%) along the direction
of flow, but there is no cross-slope. Sloping border are suitable for most crops except
those that need prolonged pounding. Therefore, when the water is applied, it flows
over the entire width as it moves down the slope along the longitudinal direction.
Water is supplied to each strip from a ditch made of earth (or concrete). Water from
the earth ditch is usually supplied to the strip by opening a path in the ditch bank.
For concrete ditches, water is supplied to the strip using a gated openings or siphons
made from suitable materials (e.g. plastic pipes) (Kumar and Vishal Kumar 2012).
For groundwater sources, underground concrete pipes are used instead of supply
ditches. As the water is discharged, it flows along the strip towards the lower end
in the form of sheet. It is confined between levees. It infiltrates the soil as it flows.
When the flow approaches the lower end, the supply to the strip is stopped. On a
relatively leveled field, the strips are laid along the general slope of the field. In this
case, the strips are straight and parallel to one another. On a relatively steep field, the
strips are aligned along the contours, with their longer sides parallel to the contour.
In other case, the strips are curved, these strips are known as contour strips (Zerihun
et al. 2013).
In border method, the precision of the field topography is critical, although the
extended length of strips allows the use of machineries for better leveling.
Border methods are grouped into three major categories: (fixed flow, cut back,
and tail water reuse) depending on the management strategy adopted.
Generally, field efficiency ranges from good to excellent depending on the design
and installation of the border strips and good water management. With a slope range
of 0.001–0.002, water efficiency of 70–75% can be achieved on silty clay to clay
soil with water application depth of 75–100 mm. For higher efficiency, stream size
and flow must be controlled to match the moisture depletion rate of the soil to obtain
approximately corresponding infiltration rate at both upper and lower ends (Arora
2014).