Free Essay Example on Soil Drainage

The way human beings depend on soil and water is vast. trees, houses, gardens, flowering plants, lawn grasses to mention many but a few all rests on top of the soil. The importance of soils therefore prompts us to practice good soil drainage. Soil drainage is how well the soils can handle and move rainfall, surface and sub-surface water. A well-drained soils will not remain soggy for much time. Soils that do not retain water for a long period are the ones that are best to set up buildings and can allow variety of plants to grow. Poorly drained soils mostly have its water table just a few inches from the surface of the ground at the better part of the year. This research will be talking about soils that require drainage, drainage types and methods of drainage.

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The type land soils that require drainage are land that have water table, water logging soils, excessive moisture content above the filed capacity, humid regions that have continuous rainfall and lands that have fine textured soils (Troeh, 2004). Soils with water table at the surface normally occurs due to the gauge pressure becoming zero that is the water pressure head being equal to the atmospheric pressure. The diagram below illustrate the different water tables for soils

Soil drainage types

There are two types of drainage that are surface drainage and sub-surface drainage. Surface drainage is form of drainage whereby water is removed from the surface of land. To accomplish this type of drainage then ditches are dug, they are also known as open drains. The shallow ditches are then supposed to be discharged to a deeper collector that is to be drained. The condition for surface drainage is that the land should be artificially sloped.

Subsurface drainage

This type of drainage involve removing of excess water from the root zone. The process is only achieved through digging of deep open drains or even buried pipes.

Deep open drains

The excess water are to drain to the root zone. The use of deep open drainage is most effective in break of slope areas, areas that have aquifers or soils of high transitivity. Construction of a deep drainage can be done using various excavation machine (Jamieson, Gordon, Sharples, Stratton & Madani, 2002). The illustration below shows the effect of open drain on water table.

Pipes drains

This form of drainage pipe drains are buried with openings dug through the soil water. The pipes are then used in conveying the water. The drain pipes are normally made using clay pipes or concrete. The pipes are to be placed in trenches using machines. The drainage water will then enter the pipes through the joints as illustrated below.

The pipe spacing affects the how effective the drainage is. The chart below illustrate how pipe spacing is directly proportional to the effectiveness of soil drainage.

Mole drainage

This method of drainage can be classified as a gravel mole drains. The suitability of the drainage depend solely on the clay content and type. The stone gradient also matters a lot. Moles are dug using the mole plough that will create a channel in the area of the soil profile that is depending on the clay content. The use of mole drains is best for heavy soils that have high clay content. After the mole channel has been formed it will have the capacity of maintaining the drainage for many years. The figure below illustrate how mole drain functions over collector pipe system.

Gravel mole drains

This method is best suited for use in soils that do not have sub surface pipes being suitable for use. It can also be used in a situation whereby the mole drains do not have long life span. In case of slaking soils the gravel mole drain will serve the purpose of maintaining the shape of moles that is after moling has been done. The gravel drain mole is a channel that with a small diameter that is filled with washed sand. The problem with this method is that there are few gravel machine and at the same time limited. The use of gravel method is useful but most of the time it requires an expert opinion for the best conditions that it can be used.

Interceptor drains

This methods of soil drainage has drains being installed at the bases of slopes that at the exact pint where there is change of gradient. It is best to put it in a position whereby the steeper slope will met the flats. The soil type at the slope matters when using this method (Willardson, Boles, & Bouwer 2011).The most preferred soil is the one which is permeable than those that are on the flat side of the slope. The condition above will therefore force water at the slope to come to the surface that at the change of the slope. Also at the slope the interceptor drains will be installed on the springs lines. The purpose of installing the spring lines is to intercept the spring water.

References

Jamieson, R. C., Gordon, R. J., Sharples, K. E., Stratton, G. W., & Madani, A. (2002). Movement and persistence of fecal bacteria in agricultural soils and subsurface drainage water: A review. Canadian Biosystems Engineering,44(1), 1-9.

Troeh, F. R. (2004). Landform parameters correlated to soil drainage. Soil Science Society of America Journal, 28(6), 808-812.

Willardson, L. S., Boles, A. J., & Bouwer, H. (2011). Interceptor drain recovery of canal seepage. Transactions of the ASAE, 14(4), 738-0741.