Surface Irrigation - Border Irrigation
Border Irrigation
This method makes use of parallel
ridges to guide a sheet of flowing water as it moves down the slope. A border
may be level or graded depending on the provision of no. of some scope in
longitudinal direction. The slope in transverse direction is zero in both the
cases. In graded border, the land is divided into a number of long parallel
uniformly graded strips of land called borders that are separated by low
ridges. It has no cross slope but uniform gentle in the direction of irrigation.
The essential feature is to provide such a surface that water can flow down
with uniform depth. Each strip is irrigated independently by a sheet of water
confined by the border ridges.
The width of border strip depends
on the size of irrigation stream, amount of cross slope, kind and width of farm
machinery and the desired accuracy of land leveling. Length of border strips
should be limited to 400 meters. Longer strips are advantageous as they reduce
the cost of water conveyance system. Length affected by the infiltration rate
of soil, depth of water applied surface roughness and texture of soil.
Under graded border, care should
be taken to design the border such that minimum infiltrated depth is achieved
at upstream end of border and control over excessive accumulation of crop. A
border width of 30 meters and length of 200 meters has been found ideal under
irrigated conditions of the Punjab.
Suitability
Border
irrigation is adapted to most soils where depth and topography permit the
required land leveling at a reasonable cost and without permanent reduction in
soil productivity. It is more suitable to soils having moderately low to
moderately high infiltration rates such as loamy soils.
It is not used in coarse sandy
soils having high infiltration rates and very low infiltration rates.
It is suitable to irrigate all
close growing crops like wheat, barley, fodder crops and legumes. Graded border
is however not suitable for crops such as rice which require standing water
during most part of its growing season.
Advantages: border dikes can be constructed economically with
simple farm implements. Uniform distribution and high application efficiency
are possible if system is properly designed and manages. Large irrigation
streams can be effectively used. It is suitable for mechanical farming. This
method saves land and water due to reduction of water channels and permanent
dikes.
Disadvantages: this method requires proper land leveling and
uniform gentle slope in the direction of irrigation. Usually large irrigation
streams are required. Land is wasted under ridges. However they are temporarily
constructed to guide flow of water. Time take to irrigate increases with length
of border. Therefore, excessive long borders cannot be accommodated for smaller
stream flows.