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close this bookSurface Water Drainage for Low-Income Communities (WHO, 1991)
View the document(introduction...)
View the documentAcknowledgements
Open this folder and view contents1. Surface water drainage in urban areas
Open this folder and view contents2. Drainage options
Open this folder and view contents3. Rehabilitation and maintenance
Open this folder and view contents4. Community participation
View the documentAnnex 1. Glossary
View the documentAnnex 2. Design calculations
View the documentAnnex 3. Terms of reference for consultants
View the documentAnnex 4. Resources for the orientation of the drainage committee

Annex 1. Glossary

alluvial

Deposited by a river, normally on a flood plain near the river's mouth

baffle

Slab or board partly closing a drainage channel to divert or slow down the flow of water

bedding

Sand or gravel placed beneath a drainage pipe or channel element to support it evenly

by-laws

Laws made at local level

catchment area

Area of ground from which rainwater will flow to a single point

checkwall

Wall placed across a drainage channel to prevent scouring

concentration

Time required for rainwater from all over a catchment area to flow to a single

time

point

crown

The highest point in the cross-section of a pipe

culvert

Drain for carrying water underneath a road or pathway

curing

Treatment of concrete by keeping its surface damp for the first seven days after placing, to ensure it develops its full strength

dissipator

Checkwall built of loose boulders which allows water to pass through the boulders but slows it down, dissipating its energy

element

Precast section of drainage channel lining or pipe

erosion

Removal of soil by the action of water

gabion

Bundle or bale of stones bound in wire or other mesh

grader

Machine used for road construction and maintenance, with a blade fixed between its front and rear wheels

groundwater

Water located beneath the ground surface

gully pot

Basin incorporated into the inlets of some closed drainage systems to collect sediment, which must be removed from it regularly

impermeable

Describes a material through which water can not pass

in situ concrete

Concrete placed and allowed to set in the position where it will remain

infiltrate

(of a fluid) To pass into the pores or small spaces in a solid, e.g., soil

infrastructure

Permanent facilities for the common use of a community

invert

The lowest point in the cross-section of a pipe

landfill

Earth or rubble spread over the ground to raise the level

manhole

Underground chamber of brick or concrete, permitting entry to closed drains and sewers

masonry

Construction of brick or stones held together with mortar

mortar

Mixture of cement, sand and water

municipality

Organ of local government in a city or urban district

parasite

An organism that lives on or in another living organism and draws nourishment from it

pantograph

Instrument for mechanical copying of drawings or plans on the same or a different scale

planimeter

Instrument for measuring areas on paper

polder

Low-lying area of land protected from flooding by an embankment

primary drain- age system

System of large drains, each serving a wide area of a city

receiving water body

Body of water into which water flows from a drainage system

refuse

Rubbish, garbage

return period

Average interval between storms or floods of a given severity

runoff

Water from rainfall, flowing over the ground and into drains and streams

runoff

Proportion of rainwater that flows over the ground and is thus likely to enter

coefficient

a drainage system

scouring

Washing away of soil (erosion) around, beneath or in the bed of a drain

secondary drain- age system

Network of small drains within a neighbour hood serving a small catchment area and discharging into the primary drainage system

self-cleansing speed of flow

Speed of flow in a drain or sewer sufficient to prevent the accumulation of sediment

sewage

Human excrete and wastewater, flushed along a sewer

sewer

A pipe containing wastewater or sewage

slope

Gradient; inclination to the horizontal

sludge

Mixture of solids and water deposited on the bottom of drains, septic tanks, etc.

sluice gate

Structure that can be opened or closed to control the passage of water

stormwater

Water from rainfall flowing in a drain or sewer

topography

Shape of the ground surface, including the position of natural and manmade features

trapezoidal

Describes a drainage channel with sloping sides and a flat bottom

turnout

Drain taking water away from the side of a road

weephole

Small hole in a drainage channel lining through which water can flow, to relieve groundwater pressure