Changes

==Spacing drainage pipes==

==Spacing drainage pipes==

Laterals drains should be spaced between 3 - 4 m apart.

Lateral drains should be spaced between 3 - 4 m apart.

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This is based on an analysis of Hooghoudt's equation<ref>H.P.Ritzema, 1994, Subsurface flow to drains. Chapter 8 in: H.P.Ritzema (ed.), Drainage Principles and Applications, Publ. 16, pp. 236-304, International Institute for Land Reclamation and Improvement (ILRI), Wageningen, The Netherlands. ISBN 90-70754-33-9</ref>:

An analysis of Hooghoudt's equation<ref>H.P.Ritzema, 1994, Subsurface flow to drains. Chapter 8 in: H.P.Ritzema (ed.), Drainage Principles and Applications, Publ. 16, pp. 236-304, International Institute for Land Reclamation and Improvement (ILRI), Wageningen, The Netherlands. ISBN 90-70754-33-9</ref> in relation to loamy or clayey native soils, where ''K_media''>>''K_soil'', finds the first term of the numerator negligible, such that:

<math>Drain\ spacing=\sqrt{\frac{8K_{soil}H\left(D_{i}-D_{d}\right)\left(D_{d}-D_{w}\right)+4K_{soil}\left(D_{d}-D_{w}\right)^{2}}{q}}</math>

<math>Drain\ spacing=\sqrt{\frac{8K_{soil}H\left(D_{i}-D_{d}\right)\left(D_{d}-D_{w}\right)+4K_{soil}\left(D_{d}-D_{w}\right)^{2}}{q}}</math>

In loamy or clayey native soils, ''K_media''>>''K_soil'', and the first term of the numerator becomes negligible. This renders the equation effectively:

may be simplified as:

<math>Drain\ spacing=\sqrt{\frac{4K_{media}\left(D_{d}-D_{w}\right)^{2}}{q}}</math>

<math>Drain\ spacing=\sqrt{\frac{4K_{media}\left(D_{d}-D_{w}\right)^{2}}{q}}</math>

Where:

Where: