Major floods are generated on farm fields and can be prevented by making environmentally sensitive changes to land use and management practices. Marked reductions in flood levels and in the amounts of silt being deposited in river channels can be brought about by relatively minor adjustments to farming practices and can lead to significant improvements in land quality, the stabilisation of crop yields, less-costly farming and more plentiful habitats for wild flora and fauna.
The amount of rainwater flowing off agricultural lands can vary from 90% to virtually zero depending on whether the land is under crops, pastures or woodland. In addition, the types of management practices adopted by the land user can dramatically increase or decrease the average amount of soil loss and run-off emanating from lands within each of these three categories.
Floodwater cascading down cropland carries with it large amounts of valuable topsoil vital to healthy crop growth; and can wash away up to one half the applied fertilizer along with a large proportion of the planted seed.
Soil erosion has been widely recognised as a major problem in tropical agriculture, and thus for large parts of the developing world.
In the UK, and throughout Europe, the currently excessive level of rain running off agricultural lands is costing farmers and the general public billions of pounds yearly in terms of crop and fertilizer losses, pollution from agricultural chemicals, flooding of urban areas, silting of channels, increased costs of water treatment, damage to infrastructures, and the disruption of commercial and industrial activities. These factors directly impact not only on the economic well-being of the country but also reflect directly on the general physical and mental health of the population.
Soil erosion in the UK. A heavy deposit of silt at the bottom of a land after a storm in Worcestershire, UK.