Drainage of land

Drainage is the natural or artificial removal of a surface's water and sub-surface water from an area. The internal drainage of most agricultural soils is good enough to prevent severe waterlogging (anaerobic conditions that harm root growth), but many soils need artificial drainage to improve production or to manage water supplies.

The ancient Indus of sewerage and drainage that were developed and used in cities throughout the civilization were far more advanced than any found in contemporary urban cities in the Middle East and even more efficient than those in some areas of the Indian Subcontinent today. All houses in the major cities of Harappa and Mohenjo-daro had access to water and drainage facilities. Waste water was directed to covered gravity sewers, which lined the major streets.

The invention of hollow-pipe drainage is credited to Sir Hugh Dalrymple, who died in 1753.

New drainage systems incorporate geotextile filters that retain and prevent fine grains of soil from passing into and clogging the drain. Geotextiles are synthetic textile fabrics specially manufactured for civil and environmental engineering applications. Geotextiles are designed to retain fine soil particles while allowing water to pass through. In a typical drainage system they would be laid along a trench which would then be filled with coarse granular material: gravel, sea shells, stone or rock. The geotextile is then folded over the top of the stone and the trench is then covered by soil. Groundwater seeps through the geotextile and flow within the stone to an outfell. In high groundwater conditions a perforated plastic (PVC or PE) pipe is laid along the base of the drain to increases the volume of water transported in the drain.

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Wikipedia