Surface water run-off
Surface water run-off is: 'Water flow over the surface of roofs and ground surface to a drainage system. Ground surface run-off occurs if the ground is impermeable, is saturated or if the rainfall is particularly intense.'
Volume of run-off is: 'The volume of run-off that is generated by rainfall occurring on the site. This is typically measured in cubic metres. Additional predicted volume of run-off is the difference between the volumes of run-off; pre-development, greenfield and post development.'
Ref Home Quality Mark One, Technical Manual SD239, England, Scotland & Wales, published by BRE in 2018.
NB Run-off coefficient is a measure of the amount of rainfall that is converted to run off.
A recurrence interval is: ‘The average time between runoff events that have a certain flow rate, for example, a flow of 2 m/s might have a recurrence interval of two years.’ Ref The SuDS Manual (C753) published by CIRIA in 2015.
Climate Change 2021, The Physical Science Basis, published by the Intergovernmental Panel on Climate Change in 2021, defines runoff as: ‘The flow of water over the surface or through the subsurface, which typically originates from the part of liquid precipitation and/or snow/ice melt that does not evaporate, transpire or refreeze, and returns to water bodies.’
[edit] Related articles on Designing Buildings
Featured articles and news
Net zero electricity grids BSRIA guide NZG 5/2024
Outlining the changes needed to transition to net zero.
CIOB Global Student Challenge 2024
Universitas Indonesia wins for second year running.
New project and cultural district described in detail.
The nature of EPCs, crticism and inaccuracies.
History, issues and redesign.
From waste recycling to energy performance the hierchy.
An introduction to WERCS and WEEE responsibilities
Dealing 2 million tonnes of waste equipment a year.
Global BACS Market: analytics and optimisation
A BSRIA glance at building automation and control systems.
What it is and how to use it.
Types of insulating plaster by binder and insulant.
Investors in People: CIOB achieves gold
Reflecting a commitment to employees and members.
Scratching beneath the surface; a guide to selection.
ECA 2024 Apprentice of the Year Award
Entries open for submission until May 31.
UK gov apprenticeship funding from April 2024
Brief summary the policy paper updated in March.
For the World Autism Awareness Month of April.