H

head-discharge
The relationship between a discharge rate and the water level causing the discharge.

highway
Any road, track, bridleway or public-footpath in private or public ownership that is not associated with an individual property.

highway drainage system
A drain or sewer constructed for the purpose of draining a highway.

hydraulic analysis
Assessment of the hydraulic behaviour of a system. Simulation hydraulic modelling of a sewerage network to determine its performance.

hydraulic capacity
The maximum flow that a pipe of given dimensions, slope and roughness can carry (often quoted as pipe-full capacity, which is a little less than the maximum capacity).

hydraulic performance
The measure of the capacity of the system or part thereof.

hydraulic simulation
The computational process carried out by a computer model to analyse the behaviour of a system (sewer network) due to an external influence (rainfall).

hydrograph
A graph showing, for a given point on a stream or conduit, the discharge, stage, velocity, available power or other property of water with respect to time.