A drainage tunnel, called an emissary in ancient contexts, is a
tunnel or channel created to
drain water, often from a
stagnant or variable-depth body of water. It typically leads to a lower stream or river, or to a location where a
pumping station
Pumping stations, also called pumphouses in situations such as drilled wells and drinking water, are facilities containing pumps and equipment for pumping fluids from one place to another. They are used for a variety of infrastructure system ...
can be economically run. Drainage tunnels have frequently been constructed to drain
mining districts or to serve
drainage district
Drainage districts occur in England and Wales, varying in size from a few hundred acres to over , all in low-lying areas of the country where flood risk management and land drainage are sensitive issues. Most drainage districts are administered by ...
s.
Etymology
Emissary comes from Latin ''emissarium'', from ''ex'' and ''mittere'' 'to send out'.
Ancient world
The most remarkable emissaries carry off the waters of lakes surrounded by hills.
In
ancient Greece
Ancient Greece ( el, Ἑλλάς, Hellás) was a northeastern Mediterranean civilization, existing from the Greek Dark Ages of the 12th–9th centuries BC to the end of classical antiquity ( AD 600), that comprised a loose collection of cu ...
, the waters of
Lake Copais were drained into the
Cephisus; they were partly natural and partly artificial. In 480 BC,
Phaeax built drains at
Agrigentum in Sicily: they were admired for their sheer size, although the workmanship was crude.
The
ancient Romans
In modern historiography, ancient Rome refers to Roman civilisation from the founding of the city of Rome in the 8th century BC to the collapse of the Western Roman Empire in the 5th century AD. It encompasses the Roman Kingdom (753–50 ...
excelled in the construction of emissaries, as in all their hydraulic works, and remains are extant showing that lakes
Trasimeno,
Albano and
Nemi were all drained by means of emissaries. The case of
Lake Fucino is remarkable in two ways: the attempt to drain it was one of the rare failures of Roman engineering, and the emissary is now completely above ground and open to inspection.
Julius Caesar
Gaius Julius Caesar (; ; 12 July 100 BC – 15 March 44 BC), was a Roman general and statesman. A member of the First Triumvirate, Caesar led the Roman armies in the Gallic Wars before defeating his political rival Pompey in a civil war, an ...
is said to have first conceived the idea of this stupendous undertaking
(Suet. Jul. 44) with the
tunnels that bring his name,
Claudius
Tiberius Claudius Caesar Augustus Germanicus (; 1 August 10 BC – 13 October AD 54) was the fourth Roman emperor, ruling from AD 41 to 54. A member of the Julio-Claudian dynasty, Claudius was born to Drusus and Antonia Minor ...
inaugurated what was to have been a complete drainage schem
(Tac. Ann. xii.57) but the water level dropped by just 4 meters and stabilized, leaving the lake very much there. Hadrian tried it again, but failed; and it was not until 1878 that Lake Fucino was finally drained.
''The initial text of this section was an abridgment from Smith's Dictionary of Greek and Roman Antiquities (1875 edition, public domain).''
Modern examples
Modern examples of drainage tunnels include the
Emisor Oriente Tunnel near Mexico City as well as the
Tunnel and Reservoir Plan in Chicago.
External links
Emissarium the full article in Smith's Dictionary
* Walter Dragoni, Costanza Cambi, Field Trip Guidebook for "Hydraulic Structures in Ancient Rome", field trip of the ''42nd Congress of the International Association of Hydrogeologists'', Rome, September 2015
full text
See also
*
Storm drain
A storm drain, storm sewer (United Kingdom, U.S. and Canada), surface water drain/sewer (United Kingdom), or stormwater drain (Australia and New Zealand) is infrastructure designed to drain excess rain and ground water from impervious surfa ...
Flood control
Roman aqueducts
Ancient Roman architectural elements
Hydraulic engineering
{{Architecturalelement-stub