Ditch - Sustainability of Drainage Ditches

Sustainability of Drainage Ditches

Drainage ditches play major roles in agriculture throughout the world. Improper drainage systems accelerate water contamination, excessively desiccate soils during seasonal drought, and become a financial burden to maintain. Industrial earth-moving equipment facilitates maintenance of straight drainage trenches, but entrenchment results in increasing environmental and eventually profound economic costs over time.

Sustainable channel design can result in ditches that are largely self-maintaining due to natural geomorphological equilibrium. Slowed net siltation and erosion result in net reduction in sediment transport. Encouraging development of a natural stream sinuosity and a multi-terraced channel cross section appear to be key to maintain both peak ditch drainage capacity, and minimum net pollution and nutrient transport.

Flooding can be a major cause of recurring crop loss — particularly in heavy soils — and can severely disrupt urban economies as well. Subsurface drainage to ditches offers a way to remove excess water from agricultural fields, or vital urban spaces, without the erosion rates and pollution transport that results from direct surface runoff. However, excess drainage results in recurring drought induced crop yield losses and more severe urban heat or desiccation issues.

Controlled subsurface drainage from sensitive areas to vegetated drainage ditches makes possible a better balance between water drainage and water retention needs. The initial investment allows a community to draw down local water tables when and where necessary without exacerbating drought problems at other times.