Some recent studies on estuarine physical processes and water quality improvement in the Golden Horn


ALPAR Ş. B., Ünlü S.

General Assambly of European Geosciences Union, France, 1 - 04 April 2004

  • Publication Type: Conference Paper / Full Text
  • Country: France
  • Istanbul University Affiliated: Yes

Abstract

The Golden Horn - which makes Istanbul metropolis (Turkey) what it is - is one of the
coastal plain estuaries that provide a broad range of services to society. This historic
estuary was a marvel of nature and preserved its natural beauty for centuries until the
grey hands of industrialization hit there ignorantly. Since the early 1950Šs it has been
suffering from severe domestic and industrial pollution that resulted in heavy and
unplanned urbanization along its shorelines. Overall urban planning was disregarded
and only short term measures were taken, with the result that the area became a dense
industrial zone lacking hygienic standards or even basic infrastructural or technical
facilities. Increased sediment deposition coupled with weakened water circulation
has hindered the self-purification capacity of the estuary. Last decade, a collaborative
environment project was carried out to save the Golden Horn from its malodorous,
swamp-like state. These efforts made available to the citizens many recreation areas,
entertainment facilities and cultural opportunities; as well as revived and brought
its historic mission back along its coasts. In order to promote, ensure and sustain
the rational and efficient management of the Golden Horn estuarine system where
scientists, organisations concerned, local communities and individuals with diverse
expertise would collaborate within a partnership approach; one should understand
what problems this estuary is opposed to.
On the basis of new oceanographic data, we make an attempt to summarize both
some of the more recent estuarine physical studies (hydrographic structure, water
circulation and quality) that have been undertaken during the last several years in
the Golden Horn, as well as some of the trends in progress that they represent. The
estuarine water body is mainly governed by the hydrodynamic conditions of the
Strait of Istanbul (Bosphorus) and the input from creeks. The major pollutants are
suspended solids, organic matter, nutrients, heavy metals and hydrocarbons. These
pollutants were discharging into the estuary from point and non-point sources. Fresh
water drainage seasonally delivers nutrients in dissolved and particulate form. The
exchange of the estuarial waters with the open sea allows rapid changes in salinity,
temperature, nutrients and sediment load. Transient (3 days) but important PAH
pollution has even been defined within the estuarine surface waters due to some oil
spill originated from ship accidents occurred in the Bosphorus. Acoustic Doppler data
show that the current system in the estuary could be much more intricate, affected by
bathymetry and eddies at the exit. The floating bridges crossing the estuary still affect
the water circulation in a negative way.
These results can be assessed as baseline input for the hydrological and environmental
management of the Golden Horn estuary. Cooperative management arrangements are
essential to achieve successful management of this historic estuary. Because of the
possible environmental impacts, new projects and operation / maintenance activities
must be consistent with national environmental policies which should be based on
protection/usage equilibrium enabling human activities and natural environment to
co-exist in productive harmony including preservation of historic and archeological
resources of the area. The efforts relating to the rehabilitation program should
encompass both the water column and bottom deposits so as to prevent uptake of
chemicals into the food chain, whilst protection should cover the upland habitat and
drainage areas of the creeks flowing into the estuary with in-situ pollution measures
altogether.