Sistan Basin

The Sistan Basin is an inland endorheic basin encompassing large parts of south-western Afghanistan and south-eastern Iran, one of the driest regions in the world and an area subjected to prolonged droughts. Its watershed is a system of rivers flowing from the highlands of Afghanistan into freshwater lakes and marshes and then to its ultimate destination: Afghanistan's saline Godzareh depression, part of the extensive Sistan terminal basin. The Helmand River drains the basin's largest watershed, fed mainly by snowmelt from the mountains of Hindu Kush, but other rivers contribute also.cite web
url=http://postconflict.unep.ch/publications/sistan.pdf
title=History of Environmental Change in the Sistan Basin 1976 - 2005
publisher=
accessdate=2007-07-20] [cite web
url=http://www.iwlearn.net/iw-projects/Fsp_112799470223
title=Restoration, Protection and Sustainable Use of the Sistan Basin
publisher=
accessdate=2007-07-20]

Ecological importance

Since the economy of the region is based on agriculture, subsistence depends on snowmelt andrainfall in the high mountains to sustain the health of the Sistan Basin and its wetlands. This source of water severely fluctuates over time and therefore has resulted in fundamental problems of survival for human settlements in the area. A severe drought began at the turn of twenty-first century and as of 2005 has lasted six years with extreme consequences for the populations.

The region's economic survival is dependent on the wetland's products. For example, beds of reeds provide livestock food, cooking and heating fuel, and the raw materials for structures and handicrafts. Water availability affects the income derived from fishing and hunting, an important source of income. The result of the drought has been the collapse of the local economy as well as destruction of the wetland's ecological system, causing damage to the agriculture in the delta based on the Helmand River's irrigation. [cite web
url=http://www.envirosecurity.org/actionguide/view.php?r=110&m=publications
title=History of Environmental Change in the Sistan Basin
publisher=www.envirosecurity.org
accessdate=2007-07-20]

Archeology

For more than 5,000 years the Sistan basin has been inhabited by sophisticated cultures and thus contains somekey archaeological sites. The Shahr-i Sokhta, or "Burnt City", in Iran, build in 3100 B.C. near a currently dried-upbranch of the Helmand River was abandoned one thousand years later, most likely due climate changes that altered the river course. Kang and Zaranj in Afghanistan were major medieval cultural hubs, now covered by sand.Here signs of historical irrigation systems, including canals, are still visiblein the Dasht-e-Margo and Chakhansur areas while elsewherecanals are filled with silt and agricultural fields buriedby shifting sand. Today the area issparsely populated.

Notes

External links

* [http://visibleearth.nasa.gov/view_rec.php?id=16549 Dust storm over Afghanistan and Pakistan]
* [http://earthobservatory.nasa.gov/Study/hamoun/ From Wetland to Wasteland: The Destruction of the Hamoun Oasis]
* [http://www.briancoad.com/Introduction/sistanbasin.htm Freshwater Fishes of Iran: Introduction - Drainage Basins - Sistan]