Britannica
Sources used in this answer
Why are surface ditches used to drain clay soils?
Created from Britannica articles
using AI.
AI can make mistakes, so verify using Britannica articles.
land reclamation
The Yser River flowing through reclaimed farmland in Belgium.
Surface ditches are used to drain clay soils because these soils typically possess low permeability, meaning they have a limited ability to transmit water through their internal structure.1
Because water cannot easily move through the soil profile to reach subsurface drains, it must be removed via surface flow. To facilitate this, regularly spaced small ditches are constructed across the area, often combined with land grading or forming operations to create slopes that direct water toward these field ditches and eliminate low spots where water might otherwise pond. This surface drainage system is often the only effective method for improving drainage in soils that absorb or transmit water slowly.12