ADLib Glossary (Q to R)

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Surface runoff

Run-off can be described as contaminated water running off a surface caused by the surface already being saturated, i.e. at capacity. The speed at which liquid soaks into the soil is important in working out the risk of run-off.

Water pounding on the soil surface shows that the liquid is being applied faster than it can soak into the soil. There is a greater risk of run-off on sloping land. Application should be stopped or the rate reduced depending on the circumstances. On some sites, even a small amount of rain will cause run-off.

Run-off can frequently contribute to pollution problems if the run-off water is contaminated with pesticides or fertilisers. It can also contribute to nitrate loss.

Current research has shown that one of the major environmental problems associated with run-off is the addition of suspended solids to watercourses. High concentrations of suspended solids, also known as siltation or sedimentation, causes cloudiness of the water effecting the quantities of sunlight that infiltrate the water. This in turn effects aquatic life.

Silt resulting from run-off from agricultural land may also be contaminated with phosphates and pesticides adding to the pollution problem.

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