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| Glossary ยป F |
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GlossaryThis glossary is copied from the Stormwater Manual of Western Australia Chapter 11: Further Information. References are available from this chapter. A B C D E F G H I J K L M N O P Q R S T U V W X Y Z FFilter: A layer of granular material designed to intercept fine particulate material. It may be used as part of a subsoil drain, or as a structure to treat surface runoff prior to recharge to groundwater or discharge to a drain. (ARMCANZ & ANZECC 2000.) Filter strip: See ’buffer strip’. First flush: Describes situations when contaminants (e.g. sediments) that have accumulated on impervious surfaces are transported at the beginning of a rainfall event. This results in high pollution concentrations at the start of the runoff hydrograph, reducing to lower levels before the flood peak occurs. (Argue 2004.) Flashiness: Where water levels rapidly peak and decline. Floodplain: The portion of a waterway valley next to the channel which is covered with water when the waterway overflows its banks during major flow events (Water and Rivers Commission 2000c). Freeboard: The distance between the maximum water surface elevations anticipated in design and the top of retaining banks or structures. Freeboard is provided to prevent overtopping due to unforeseen conditions, and/or events greater than the maximum design event of the structure. Frequency: See ’average recurrence interval’. |
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