A detention basin in which the runoff is stored beyond the time normally required for attenuation. This provides extra time for natural processes to remove some of the pollutants in the water.

The process by which the Earth's surface or soil loses moisture by evaporation of water and by uptake and then transpiration from plants.

A management agreement for an area or project set up to plan and make sure the declared management objectives for the area or project are met. Environmental Management Plans are often undertaken as part of an environmental impact assessment and are set out in several stages with responsibilities clearly defined and environmental monitoring procedures in place to show compliance with the plan.

A measure of environmental impact based on the distance that resources for a development are transported.

Single occurrence of an event that the likely to occur very infrequently (e.g. long drought or big storm etc.)

Single occurrence of a rainfall period before and after which there is a sufficient dry period to define its effect on the sewerage system.

The drying out process of the ground surface, which constitute a minor part of the losses taken into account within rainfall runoff loss models.

The progressive enrichment of surface waters, particularly non-flowing bodies of water such as lakes or ponds, with dissolved nutrients, such as phosphorous and nitrogen compounds, which accelerate the growth of algae and higher forms of plant life.

Detachment and movement of soil or sedimentary deposits by the flow of water, such as over the ground surface or within a pipe or channel.

Wastewater or other liquid, partially or completely treated, or in its natural state, flowing out of a pipe or a treatment plant.