The Sistan Basin is an inland

endorheic basin An endorheic basin ( ; also endoreic basin and endorreic basin) is a drainage basin that normally retains water and allows no outflow to other external bodies of water (e.g. rivers and oceans); instead, the water drainage flows into permanent ...

encompassing large parts of southwestern

Afghanistan Afghanistan, officially the Islamic Emirate of Afghanistan, is a landlocked country located at the crossroads of Central Asia and South Asia. It is bordered by Pakistan to the Durand Line, east and south, Iran to the Afghanistan–Iran borde ...

and minor parts of southeastern

Iran Iran, officially the Islamic Republic of Iran (IRI) and also known as Persia, is a country in West Asia. It borders Iraq to the west, Turkey, Azerbaijan, and Armenia to the northwest, the Caspian Sea to the north, Turkmenistan to the nort ...

. It is one of the driest regions in the world and an area subject to prolonged

drought A drought is a period of drier-than-normal conditions.Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, M. Barlow, R. Cerezo-Mota, A. Cherchi, T.Y. Gan, J. Gergis, D. Jiang, A. Khan, W. Pokam Mba, D. Rosenfeld, J. Tierney, ...

s. Its watershed is a system of rivers flowing from the highlands of Afghanistan into

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include non-salty mi ...

lake A lake is often a naturally occurring, relatively large and fixed body of water on or near the Earth's surface. It is localized in a basin or interconnected basins surrounded by dry land. Lakes lie completely on land and are separate from ...

s and

marsh In ecology, a marsh is a wetland that is dominated by herbaceous plants rather than by woody plants.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p More in genera ...

es 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 The Hindu Kush is an mountain range in Central Asia, Central and South Asia to the west of the Himalayas. It stretches from central and eastern Afghanistan into northwestern Pakistan and far southeastern Tajikistan. The range forms the wester ...

, but other rivers contribute also. A

basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...

hill, known as Mount Khajeh, rises beside the lakes and marshes of the basin.

Lakes

The lowest part of the Sistan Basin contains a series of shallow lakes, known as '' hamuns''. It appears that in the past there was a single Hamun Lake, but there are now three separate lakes. From north to south the lakes are:

Hamun-e Puzak

The Hamun-e Puzak lies mostly in Afghanistan. It receives water from the Shelah Charkh channel of the Helmand River, and also from the Khash River and other small rivers.

Hamun-e Sabari

The Hamun-e Sabari is split between Afghanistan and Iran. It receives water from the Parian branch of Helmand River, the Farah River and the Harut River.

Hamun-e Hirmand

The largest proportion of the Helmand River's waters flow into the Hamun-e Helmand, which is entirely in Iran, by a channel known as the Rud-e Sistan.

Hydrology

In times of flood the hamuns join into one large lake, and once every 20 years or so the floodwaters create an overflow from the Hamun-e Helmand by a normally dry river known as the Shela Rud, terminating in the Godzareh Depression. In 1885 there was an exceptional flood, and the floodwaters filled the depression for three years. In recent years, particularly during a drought from 1998 to 2005, the hamuns have dried up completely.

Ecological importance

Since the economy of the region is based on agriculture, subsistence depends on snowmelt and rainfall in the high mountains to sustain the health of the Sistan Basin and its

wetland A wetland is a distinct semi-aquatic ecosystem whose groundcovers are flooded or saturated in water, either permanently, for years or decades, or only seasonally. Flooding results in oxygen-poor ( anoxic) processes taking place, especially ...

s. This source of water fluctuates severely over time and therefore has resulted in fundamental problems of survival for human settlements in the area. A severe

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 Livestock are the Domestication, domesticated animals that are raised in an Agriculture, agricultural setting to provide labour and produce diversified products for consumption such as meat, Egg as food, eggs, milk, fur, leather, and wool. The t ...

food, cooking and heating fuel, and the raw materials for structures and

handicraft A handicraft is a traditional main sector of craft making and applies to a wide range of creative and design activities that are related to making things with one's hands and skill, including work with textiles, moldable and rigid material ...

s. 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 Agriculture encompasses crop and livestock production, aquaculture, and forestry for food and non-food products. Agriculture was a key factor in the rise of sedentary human civilization, whereby farming of domesticated species created ...

in the

delta Delta commonly refers to: * Delta (letter) (Δ or δ), the fourth letter of the Greek alphabet * D (NATO phonetic alphabet: "Delta"), the fourth letter in the Latin alphabet * River delta, at a river mouth * Delta Air Lines, a major US carrier ...

based on the Helmand River's irrigation.

Archaeology

For more than 5,000 years, the Sistan Basin has been inhabited by sophisticated cultures and thus contains some key

archaeological Archaeology or archeology is the study of human activity through the recovery and analysis of material culture. The archaeological record consists of Artifact (archaeology), artifacts, architecture, biofact (archaeology), biofacts or ecofacts, ...

sites. The Shahr-e Sukhteh, or "Burnt City", in Iran, built in 3100 B.C. near a currently dried-up branch of the Helmand River, was abandoned one thousand years later, most likely due climate changes that altered the river course. Also, Shahdad, located further to the west, on the western side of Lut desert, is a related site from the Bronze Age. Kang and Zaranj in Afghanistan were major

medieval In the history of Europe, the Middle Ages or medieval period lasted approximately from the 5th to the late 15th centuries, similarly to the post-classical period of World history (field), global history. It began with the fall of the West ...

cultural hubs, now covered by sand. Here, signs of historical irrigation systems, including

canal Canals or artificial waterways are waterways or engineered channels built for drainage management (e.g. flood control and irrigation) or for conveyancing water transport vehicles (e.g. water taxi). They carry free, calm surface ...

s, are still visible in the Dasht-e Margo and Chakhansur areas while elsewhere canals are filled with

silt Silt is granular material of a size between sand and clay and composed mostly of broken grains of quartz. Silt may occur as a soil (often mixed with sand or clay) or as sediment mixed in suspension (chemistry), suspension with water. Silt usually ...

and agricultural fields buried by shifting

sand Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is usually defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural ...

. Today the area is sparsely populated. Excavations have also revealed a citadel complex, and the remains of a Zoroastrian fire temple, on Mount Khajeh in Zabol (other name:

Sistan Sistān (), also known as Sakastān (, , current name: Zabol) and Sijistan (), is a historical region in south-eastern Iran and extending across the borders of present-day south-western Afghanistan, and south-western Pakistan. Mostly correspond ...

). There are other important sites in this area. * Dahan-e Gholaman is a major Achaemenid archaeological site. It is believed to be the capital of the ancient satrapy of Zranka/ Drangiana. * Ram Shahristan (or Abrashariyar) was an ancient capital of Sistan.

Notes

External links

Dust storm over Afghanistan and PakistanFrom Wetland to Wasteland: The Destruction of the Hamoun Oasis
{{coord, 29, 50, 07, N, 61, 56, 30, E, source:eswiki_type:airport, display=title Endorheic basins of Asia Regions of Iran Regions of Afghanistan Helmand River Landforms of Sistan and Baluchestan province Sistan Landforms of Iran Drainage basins of Afghanistan Landforms of Nimruz Province Landforms of Kandahar Province Landforms of Zabul Province