Drainage Intensity Metric

Drain spacing of 4-inch lateral, S
(m)

Minimum water-table depth
(m)

Drain depth from soil surface to drain center
(m)

Depth to restrictive layer, D
(m)

This value can be determined from Drain Spacing Tool, here.

Size and type of lateral drain pipe

Type of lateral drain pipe affects the effective radius.
3-inch 4-row regular-perf = 0.8 cm
3-inch 4-row narrow-slot = 0.6 cm
3-inch pipe with knitted sock = 4.5 cm
4-inch 4-row regular-perf = 0.6 cm
4-inch 8-row regular-perf = 1.9 cm
4-inch 4-row narrow-slot = 0.5 cm
4-inch 8-row narrow-slot = 1.6 cm
4-inch pipe with knitted sock = 5.8 cm
Please cite this reference: Ghane (2022).

Saturated hydraulic conductivity of the soil, K_e

This value can be determined from the Drain Spacing Tool, here.