Surface Runoff

Alternative label: 
Run-off, Overland flow

Surface runoff can be described as water flowing over soil, vegetation or other ground cover instead of infiltrating to the underlying soil. Surface runoff may be caused by imperviousness of the underlying material, or because the underlying material is already being saturated, i.e. at capacity. The quantity of water during storm events (and/or runoff from adjacent impervious surfaces) may exceed the infiltration capacity of the soil and receiving waters resulting in increased flood risk. The speed at which liquid soaks into the soil is important in working out the risk of runoff.ᅠ
Run-off can contribute to on-site and off-site problems via leaching and erosion. This includes:
- losses of pesticides, fertilisers or soil,
- pollution of receiving water if the run-off water is contaminated with pesticides, fertilisers or sediment,
- other biophysical impacts on the aquatic environment like excessive sedimentation and clogging, or high concentrations of suspended solid which in turn cause cloudiness of the water affecting the quantity of sunlight that infiltrates the water.

Relation type: 
Last updated: 04 Mar 2015 | Top