International Journal of Marine Science 2015, Vol.5, No.31, 1-6
1
Research Report
Open Access
Reconstructing the past fluctuations of Urmia Lake
Homayoun Khoshravan
1
, Anahita Jabbari
2
1. Head of environmental management group, the ministry of science, research and technology of Iran and associated professor of water research institute, ministry of
Energy, Iran
2. Water engineering department, Urmia University, Iran
Corresponding author email
International Journal of Marine Science, 2015, Vol.5, No.31
doi: 10.5376/ijms.2015.05.0031
Received: 04 Apr., 2015
Accepted: 05 May., 2015
Published: 11 May., 2015
Copyright
©
2015
Khoshravan and Jabbari, This is an open access article published under the terms of the Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Preferred citation for this article:
Khoshravan and Jabbari, 2015, Reconstructing the past fluctuations of Urmia Lake, International Journal of Marine Science, Vol.5, No.31 1
-
6 (doi:
Abstract
The aim of current study is to reconstruct the water level fluctuations of Urmia Lake during Pleistocene and Holocene.
Evaluation of biostratigraphy evidences in sedimentary terraces and studying the sub bottom sediments sequences have illustrated
that the water level of the lake was 45 meters higher, during upper Pleistocene, in comparison with the levels of its wet years at 1999,
and also the lake area was twice bigger at that time. The main results show that the Urmia Lake was widely dried up in two steps,
4,000 and 12,000 years ago and the deserted environment was dominant. Also it has been obvious that the climatic changes effects
during glacial and interglacial periods cause the biofacies variability of Quaternary sediments.
Keywords
Urmia lake; Sediments; Fluctuation; Holocene; Drought
Introduction
The impact of global warming on the open seas,
oceans and lakes in different parts of the globe is quite
distinct (Khoshravan 2014). So that in recent decades
along with the increasing rate of greenhouse gasses
concentrations (CO2) in atmosphere, the icebergs and
glaciers have been more vulnerable to gradual ice
melting which causes the increment of water levels in
seas and oceans. But rainfall reduction and occurrence
of more evaporation amounts in most parts of
continental areas, have caused vast droughts and most
of the lakes have been intensely shrunk due to runoff
degradation (Khoshravan 2014). In this regard some
examples are as follows: Great Salt Lake in USA and
the lakes in Iran such as: Maharloo, Parishan,
Bakhtegan, and finally Urmia Lake. It is noticeable
that the impact of climatic factors on Caspian Sea in
recent 15 years caused 80 cm shrinkage of water level
(Khoshravan 2014).Considering the area of this sea
(about 400,000 km
2
), it can be resulted that about 320
billion cubic meters of water has been lost which
equals 10 times of Urmia Lake water volume at its wet
years on 1999 (Khoshravan 2014). So the impact of
global warming on the lakes located at the North West
part of Middle East is widely accepted. The Urmia
Lake has been shrunk suddenly and so intensely since
1999, as over the past 15 years, the 8 meters water
level degradation has been designated. The scientists
have mentioned a wide range of reasons for the event
such as: the effect of causeway structure to prevent
hydraulic flows in south-north directions and
sedimentary blockage of estuaries, evaporation
increment and rainfall reduction, salt deposition on
lake bed and therefore elevating the bed level,
reducing the runoffs leading to the lake because of
dams and water structures constructed in watershed,
and finally the development of agricultural practices
in region despite of its low efficiency (Barzegar 1992,
Javanmard 2001). Considering the fact of drought
incidence in our country, it seems that natural factors
such as global temperature increasing about 1.5 C
°
over the past 15 years, along with rainfall reduction,
have caused the reduction of Urmia Lake water level,
and human activities have merely aggravated the
speed of phenomenon (Khoshravan 2014). It is
necessary to determine if climatic and geologic factors
in the past effected the hydrological regime of the lake
or not, and obtain information about oscillatory
behavior of the lake in the past, in order to predict the
lake fluctuations in future. In current study, by the
help of geological and biological evidences and clues
in the old sedimentary sequences, and in order to find
