AD 610. The Japanese and Indian entry into major dam building com-
mencedc.AD 750, and both nations made a notable contribution to the
early development of the embankment.
The period from AD 1000 onwards saw a spread of dam-building
activity, with quite rapid growth in the height of dams and in the boldness
of their concept. Of particular note was the construction of a series of
masonry gravity dams in Iran where the first true arch dam, i.e. a masonry
dam too slender to be stable as a gravity structure, was also built. The
latter dam, at Kebar, 26 m high and of 55 m crest length with a base thick-
ness of 6 m, was completed c.AD 1300. The remarkable 31 m high Sultan
Mahmud dam in Afghanistan also dates from this time. This era also saw
the commencement of serious dam building activity in many parts of
Europe, e.g. the 6 m high embankment at Alresford, in Britain (c.1195) or
the 10 m high embankments at Mittlerer Pfauen, Germany (c.1298) and at
Dvor ̆is ̆te ̆, Czech Republic (c.1367) and many others.
The dam-builders of 16th-century Spain advanced masonry dam con-
struction very considerably. The magnificent Tibi gravity dam, 42 m in
height, was completed in 1594 and followed by a series of other outstand-
ing masonry structures. The Elche masonry arch dam, 23 m high and 120 m
in length, was completed in 1640 and is also of particular merit. With the
rapid expansion of the Spanish Empire the expertise of the Spanish dam-
builders was also exported to Central and South America. Representative
of their breadth of vision and their ability to plan and to mobilize
resources, the intensive metalliferous mining activity centred on Potosí
(Bolivia) was, by the mid-17th century, served by a group of 32 reservoirs.
In the period from 1700 to 1800 the science of dam building
advanced relatively slowly. The dawn of the first Industrial Revolution and
the canal age gave considerable impetus to embankment dam construction
in Britain and in Western Europe in the period from about 1780. Design
continued to be based on a combination of empirical rules and proven
experience. Despite the lack of rational design methods, dams steadily
increased in size. As an example, the Entwistle embankment dam was
completed in England in 1838 as the first of its type to exceed 30 m in
height. In the 19th century British engineers advanced and developed
embankment design and construction very successfully, notable projects in
the UK including the magnificent Longdendale series of five principal
dams, completed between 1854 and 1877, and many similar large struc-
tures constructed in India and elsewhere overseas.
Rational methods of analysis for masonry dams were developed and
refined in various countries, notably France, Britain and the US, from
about 1865. The design of embankment dams continued to be very empiri-
cal until much later. Advances in embankment construction were depend-
ent upon the emergence of modern soil mechanics theory in the period
from 1930. Subsequent progress has been relatively rapid, and major
advances have been made in consequence of improvements in understand-
amelia
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