Describe the following water drainage systems i) Open ditch ii) Random ditch iii) Cross slope ditch iv) Parallel ditch

i) Open ditch
Ditches can be of any shape or size and they can take large volumes of water. These
drains do use up land and do need looking after. Excessive weeds should be cleared so
they continue to work properly.
At shallow gradients, ditches should have smooth beds for unrestricted water flow.
Ditches must have a sufficient fall to allow free flowing water, but not so steep that
scouring or undercutting to the bottom and sides of the channel occurs. Gradients
between 1:15 and 1:40 will work effectively. If steeper ditches are unavoidable, try to
include bends and level areas to reduce water flow speed. Short steep sections may be
piped to avoid erosion of the ditch.

ii) Random ditch
The random ditch pattern is adapted to slowly permeable soils having depression
areas that are too large to be eliminated by land smoothing or grading. Field ditches connect the major low spots and remove excess surface water from them. They are generally shallow enough to permit frequent crossing by farm machinery. Soil from the ditches can be used to fill minor low spots in the field. Field ditches should extend through most of the depressions, to assure complete drainage,
and they should follow the natural slope of the land.

iii) Cross slope ditch
A cross slope drainage system is used to drain sloping land, to prevent the accumulation
of water from higher land, and to prevent the concentration of water within a field.
The field ditches work best on slopes of less than 2 percent. The drain is located
across the slope as straight as topography will permit. The spacing of these
ditches varies with the land slope. The excavated material should be placed in low
areas or on the downhill side of the drain. Land forming or smoothing between the
ditches improves operation of the system by preventing the concentration of flow and
the occurrence of ponding.

iv) Parallel ditch
The parallel ditch pattern is suitable for flatter, poorly drained soils that have
numerous shallow depressions. In fields that can be cultivated up and down slope,
parallel field ditches are installed across the slope to break the field into shorter units
of length and make it less susceptible to erosion. The field should be farmed in the
direction of the greatest slope. Dead furrows are neither desirable nor necessary.
Although the ditches must be parallel, they need not be equi-distant. The spacing
between them depends upon the permissible length of row drainage for the soil type
and upon the amount of earth and the distance it must be moved to provide complete
row drainage. The maximum length of the grade draining to a ditch should be 660
feet.

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NatalieR answered the question on June 29, 2022 at 06:33