The management of urban water and surface water runoff within a given urban drainage basin
Sustainable Urban Drainage System, designed to reduce the potential impact of new and existing developments with respect to surface water drainage discharges
The degradation of urban water due to the addition of unwated materials. The major pollutants found in runoff from urban areas include, and viruses
Sources of water pollution in urban areas
Sediment from construction, oxygen-demanding substances, road salts, heavy metals from cars and industrial processes, petroleum hydrocarbons, pathogenic bacteria, pesticides from parks and gardens
Increased river flows in urban areas
During wet periods leads to flooding and increased erosion
Decreased river flows in urban areas
During dry periods causes extremely low flows and can damage fish spawning grounds and aquatic vegetation
Higher water temperatures
From increased urban air temperatures and discharged waste water can disturb ecological balance
Green roofs/rain gardens
Covers the roof of a building with vegetation cover/landscaping. The roof is likely to consist of an impermeable layer, a substrate or growing medium and a drainage layer, designed to intercept and hold precipitation, reducing the volume of runoff and lowering peak flows.
Allows rainwater to soak through the cracks between slabs so is better than concrete and tarmac
The benefits obtained from the regulation of ecosystem processes, in this case urban river systems, such as climate regulation, flood regulation, water purification and waste management, pollination or pest control
A design feature that in the event of flood failure, inherently responds in a way that will cause no or minimal harm to other equipment, the environment or to people. Many old concrete flood channels in urban areas were designed this way
A method of river engineering that widens or deepens rivers (and often uses concrete) to increase the capacity for flow volume at specific sections of the river. Used in urban areas to reduce flooding.
Los Angeles River
Flows through a concrete channel on a fixed course, which was built after a series of devastating floods in the early 20th century.
Shallow, broad and vegetated channels designed to store and/or move runoff and remove pollutants. Can pass the runoff to the next stage of treatment and can be designed to promote infiltration where soil and groundwater conditions allow.
Small lakes that store storm water and allow for its treatment. Support emergent and submerged aquatic vegetation along their shoreline. Sediments settle out in the pond and plants can uptake pollutants.
Can be built as part of SUDS to remove fine sediments, metals and particulates, and dissolved nutrients. Wetlands mainly treat polluted runoff, provide attenuation and deliver biodiversity and amenity.