Storm Water Management & Modelling - a study of Paldi Catchment area
Point source pollution Pollution that arises from an easily identifiable source, e.g. a WwTW outfall.
Recharge The addition of water to the groundwater system by natural or artificial processes.
Pollutant A contaminant whose concentration has increased to an objectionable level and which may cause harm to flora or fauna.
Reed bed Area of grass-like marsh plants, in or adjacent to water bodies. Artificially constructed reed beds are used to treat small volumes of the liquid component of sewage effluent. Regulator
Pollution The addition of a pollutant to the environment (a natural body of water) which diminishes the physical, chemical, radiological, or biological quality of a resource (air, water or land) and may have a negative impact on flora and fauna. Pond Depression of any size with a permanent pool of water, usually with ecological value. Poor status(1) Waters which show evidence of major alterations to the values of the biological quality elements for the surface water body type and in which the relevant biological communities deviate substantially from those normally associated with the surface water body type under undisturbed conditions.
An organisation, usually government body, with the authority to stipulate requirements such as consents for discharges to receiving waters. Residential access roads These roads link dwellings and their associated parking areas and common open spaces to distributor roads. Retention Pond A SUDS pond consisting of a significant sized permanent pool of water (up to 4 times Vt) designed to treat surface runoff by detaining the water to provide settling of sediments, and chemical and biological processing as well as provide attenuation. Often used to provide high amenity value. Return period The reciprocal of the average annual probability of exceedence of a specific flow value or event.
Porosity The percentage of the bulk volume of a rock or soil that is occupied by voids, whether isolated or connected.
Risk Risk is a measure of the combination of the likelihood of an event (hazard probability) and the severity of the outcome (consequence).
Porous asphalt An asphalt material used to make pavement layers pervious, with open voids to allow water to pass through (previously known as pervious macadam).
Risk assessment An evaluation of all the relevant risks (hazards and consequences) to enable appropriate actions or mitigating solutions to be devised.
Porous paving A permeable surface that drains through voids that are integral to the pavement.
River Basin The area of land from which all surface run-off flows through a sequence of streams, rivers and, possibly, lakes into the sea at a single river mouth, estuary or delta.
Porous surface A surface that infiltrates water to the sub-base across the entire surface of the material forming the surface, for example grass and gravel surfaces, porous concrete and porous asphalt. Priority substances Key substances, usually pollutants, identified by legislation as being critical to control from causing an impact on the environment. Probability The estimated likelihood of a storm event e.g. a 1 in 100 year flood event is one that is expected to be equalled or exceeded once every 100 years; it also has a 1% chance of occurring in any one year.
Runoff Water from precipitation which flows over surfaces and contributes to flows in a drain, sewer or receiving water. Runoff coefficient The proportion of total rainfall that appears as total runoff volume after subtracting losses, such as depression storage, infiltration and interception. Salmonid Waters High quality waters suitable for self sustaining populations of wild salmon and trout. Scour Localised erosion.
Public sewer A sewer that is vested and maintained by the responsible public authority.
Sediment Organic or inorganic material that has been transported by water, which has been deposited.
Rainfall event A single occurrence of rainfall before and after which there is a dry period that is sufficient to allow the drainage system to return to, or near to, its steady state.
Separate sewer A sewer for surface water or foul sewage, but not a combination of both.
Rainfall intensity Amount of rainfall occurring in a (short) period of time, generally expressed in mm/hr. Rainfall ratio “r� The ratio of depths for a 5 year return period event of 60 minute duration and a 5 year return period event of 2 days duration. Rainwater butt Small scale garden water storage device which collects rainwater from the roof via the down-pipe. Rainwater harvesting or rainwater use system A system that collects rainwater locally (usually from roofs, but occasionally from hard standings) rather than allowing it pass to the drainage system. Rational Method A simple drainage analysis method, used throughout the world, for calculating the peak discharge in a drainage system for pipe sizing. Receiving waters Water body (river or lake) which receives flow from point or non-point sources.
Separate Sewer System System whereby, foul sewage and stormwater run-off are kept separate and confined to individual designated sewer systems: one for foul sewage which is conveyed to treatment; and one for stormwater run-off which is discharged to water courses. Sewer A pipe or channel taking domestic foul and/or surface water from buildings and associated paths and hardstandings from two or more curtilages and having a proper outfall. Sewerage System of pipes (sewers) to transport sewage. Silt The generic term for waterborne particles with a grain size of 4-63 mm, i.e. between clay and sand. Simulation The representation of specific conditions during a specific period in a sewerage system, treatment works, river, etc., by means of a computer model. Site Control A term used in SUDS to denote drainage elements that are suitable for use in storm water management to
Akshay Anand Faculty of Geomatics and Space Application, CEPT University Internship Programme: Indian Space Research Organization, Ahmedabad