Hooghoudt's equation

Not Reviewed
Equation / Last modified by EmilyB on 2016/08/10 18:25
`Q = `
Hooghoudt's equation
Variable Instructions Datatype
`(Kb)"hydraulic conductivity of the soil above drain level"` Enter hydraulic conductivity of the soil above drain level Decimal (m/s)
`(d)"equivalent depth"` Enter equivalent depth Decimal
`(Di)"depth of the impermeable layer below drain level"` Enter depth of the impermeable layer below drain level Decimal (m)
`(Dd)"depth of the drains"` Enter depth of the drains Decimal (m)
`(Dw)"steady state depth of the waterable midway between the drains"` Enter steady state depth of the waterable midway between the drains Decimal (m)
`(Ka)"hydraulic conductivity of the soil"` Enter hydraulic conductivity of the soil Decimal (m/s)
`(L)"spacing between the drains"` Enter spacing between the drains Decimal (m)
Type
Equation
Category
vCommons
Contents
7 variables
Rating
ID
EmilyB.Hooghoudt's equation
UUID
1363829c-5f25-11e6-9770-bc764e2038f2

Hooghoudt's equation is a drainage equation describing the relation between depth and spacing of parallel subsurface drains, depth of the watertable, depth and hydraulic conductivity of the soils. It is used in drainage design.
It is written as `Q=(8*Kb*d(Di-Dd)(Dd-Dw)+4*Ka(Dd-Dw)^2)/L^2`, where:

  • `Q` = steady state drainage discharge rate
  • `Ka` = hydraulic conductivity of the soil above the drain level
  • `Kb` = hydraulic conductivity of the soil below the drain level
  • `Di` = depth of the impermeable layer below drain level
  • `Dd` = depth of the drains
  • `Dw` = steady state depth of the watertable midway between the drains
  • `L` = spacing between the drains
  • `d` = equivalent depth

References


Wikipedia (https://en.wikipedia.org/wiki/Drainage_equation)