Methods of drainage


Surface drainage

  • Simplest and commonly adopted method is India. Drainage is achieved by digging open drains at suitable intervals and depth. Irrigation channels also serve as drainage channel.
  • Surface drainage may be needed to prevent or modify saline-alkali condition in a soil by leaching. If the land is not naturally well drained, artificial drainage must be established at the same time, the irrigation system is installed.
  • See page from over irrigated areas at higher elevations and irrigation canal can damage lands in the low-lying areas. Interceptor drains may be necessary at the upper boundaries of the low-lying area to divert the seepage and to prevent water logging. Integrated irrigation and drainage planning is often necessary for laying out a farm area for efficient water use.
  • Different methods of surface drainage are adopted, depending on the topography of the land, soil characteristics and crops that are proposed to be grown.
    • Random field ditch method
      • Standing water may be present in the field at several places distributed randomly. These depressions or micro ponds are connected by means of shallow channels or ditches and these are led into an outlet.
    • Land smoothing
      • The elevated areas are cut off and excess soil is spread over lower areas, so that the surface is even with uniform slope. Excess surface run off is collected and conveyed into the field ditches provided at the lower end of the field.
    • Bedding
      • Small furrows are formed at known intervals parallel to the slope for draining out water and known as dead furrows. The land between these furrows is known as beds. Small ridge or bund is made at the centre of the bed with gradual slope to drain water into the dead furrows.
    • Parallel field ditch system
      • Almost similar to bedding system except for deep drains and uneven interval between drains.
    • Broad bed and furrow method
      • The field is laid out into 1.05 m beds and 45 cm wide furrows across the slope. About 0.5% slope is provided for the furrows for free drainage.
      • Crops are sown on the beds and furrows help in drainage of water when there is excess rain.


Subsurface drainage

  • When surface drainage is not possible due to subsoil conditions, water table and topography, subsurface drainage is resorted to remove ground water, or to lower water table.
  • Unlike open drainage, land is not wasted and there is no interference to farming operations by subsurface drainage. However, this requires less maintenance and high investments.


Last modified: Wednesday, 3 August 2011, 8:29 AM