19 terms

Water in Urban areas including hydrographs

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Water run off
Is removed from many surface areas in urban areas to prevent localised flooding
Natural water balance
The balance between inputs (precipitation), stores (soils, rocks, surface, plants) and outputs (evaporation, transpiration, runoff) to a drainage basin system is significantly disrupted by the construction of urban areas
Urban water balance
Tends to have less infiltration and evapotranspiration, greater runoff that natural systems and also has imported water and waste water losses not present in natural systems
Evapotranspiration
Is reduced in urban areas as there are fewer plants.
Infiltration is
Reduced in urban areas as concreted and tarmacked areas are impermeable and don't allow water to soak in.
Runoff
Is in large volumes and of poor water quality in urban areas as it picks up dust and pollutants created by urban processes like industry or transport.
Wastewater discharge
Liquid waste or sewage discharged into a river or the sea in urban areas
Flashy
Description of hydrographs in urban areas. Rivers are more likely to flood due to lower interception and infiltration rates
Precipitation
Is higher in urban areas due to increased presence of hygroscopic nuclei
Sewage system
The process of removing contaminants from wastewater, primarily from household sewage
Drainage system
Network of underground pipes and rains used to get rid of rainwater in urban areas
Impermeable
Any substance that will not allow water to pass through, such as concrete
Guttering
Channels water off buildings and into a drainage system
Concrete driveways
Have increased in popularity in the UK but increase localised flood risk as they do not allow water to infiltrate and exaggerate surface runoff
Base flow
Is lower in urban rivers that in rural rivers as less if fed into the system via soil and rock stores.
Lag time
Of an urban river is shorter due to drainage systems which speed the flow of water through urban areas
Higher peak discharge
Is evident in urban rivers
Steep rising and falling limbs
As water reaches urban rivers quicker via drainage networks
Hydrograph
A graph which shows the the discharge of a river, related to rainfall, over a period of time