Lake Neusiedl - is the second largest steppe lake in
Central Europe, straddling the Austrian–Hungarian border.
The lake covers 315 km², of which 240 km² is on the
Austrian side and 75 km² on the Hungarian side. The
lake's drainage basin has an area of about 1,120 km².
From north to south, the lake is about 36 km long, and
it is between 6 km and 12 km wide from east to west. On
average, the lake's surface is 115.45 m above the
Adriatic Sea and the lake is no more than 1.8 m deep. In
the past, rainfall and aridity caused significant floods
(which in 1768 enlarged the lake to its maximum
documented size of 515 km²) and significant decreases in
the lake's level, although frequently there seemed to be
no apparent connection with the weather situation.
Stratigraphy shows that the lake bed has totally dried
up at least 100 times since its formation (18,000 -
14,000 years B.C.). During recent history the lake's
complete disappearance has been documented in
considerable detail on several occasions, e.g. in
1740–1742, 1811–1813, and most recently in 1866, when
the private diary of a local, Gottlieb Wenzel, noted
that he crossed the bed of the lake on June 4 without
soiling his boots. Parts of the lake bed were claimed
for agriculture; wheat and turnips were being planted.
However, in 1871 the lake began to return and by the
spring of 1876 it had already reassumed its usual size.
The last (brief and partial) vanishing took place during
the summer of 1949 when the northern part of the lake
bed (to the approximate latitude of Podersdorf) fell dry
for a few weeks. Each time the drying-up of the lake bed
caused major environmental disruptions because the
humidifying and temperature buffering effect of the
large water body was absent, and because the winds blew
large amounts of salty dust into the surrounding
villages. On earlier occasions the lake was sometimes
referred to as a "swamp", suggesting a very low water
level with an expansion of reeds throughout the lake bed.
Two records dated to 1318 and 1324, respectively mention
a "river", implying that at this time the lake might
have been reduced to a central body of water running
from north to south.
Today the water level is controlled by a sluice on
Hungarian territory near Fertőújlak, and bilateral
issues are dealt with by the Austro-Hungarian water
commission which was established in 1956. However,
comparatively minor fluctuations of the lake's level
continue to occur. In 1965 the lake gained 100 million
cubic meters of water within a single month, raising its
level by 35 cm. The water level decreased to a similar
extent (by 30 cm) within one year as a result of the
drought of 2003. Both types of events are perfectly
within the normal range, and because of the shallowness
of the water can be either exacerbated or compensated by
the effects of wind pressure, which can temporarily
raise or reduce the local water level by as much as 75
cm. However, the lake remains sensitive to changes in
its equilibrium, as recent climate change scenario
simulations have shown.