M

major system
In the context of major and minor drainage, this refers to the route followed by storm runoff when the minor system is either inoperative or inadequate. It generally refers to roads and major above ground drainage channels.

manhole
A structure that provides access for personnel to the drain or sewer for servicing.

Manning's equation
An equation developed by Manning to relate flows in conduits to their size, shape, the gradient and the conduit roughness.

minor system
The drainage pipes, roadway channels, enclosed conduits an roof connections designed to convey runoff from "normal" storms, to eliminate or minimise inconvenience in the area to be developed. See major system.

misconnection
An incorrect connection of an inlet or drain to a drain or sewer that is not designed to carry that element of flow (eg foul sewage entering a surface water system or surface water entering a separate foul system).

model
A series of mathematical equations in a computer developed and used with he aim of replicating the behaviour of a system.

modified rational method
A modification of the Lloyd-Davies method introduced by the Wallignford Procedure whereby the coefficient of runoff was split into two entities (HR Wallingford and Institute of Hydrology, 1981b).

monitoring
The procedure of measuring effluent characteristics such as flows or pollutants by means of instruments.

Muskingum-Cunge routeing method
A method of routeing flows in channels and pipes, first applied on the Muskingum river in the USA and subsequently modified by Cunge.