The Sistan Basin is an inland

endorheic basin An endorheic basin (; also spelled endoreic basin or endorreic basin) is a drainage basin that normally retains water and allows no outflow to other external bodies of water, such as rivers or oceans, but drainage converges instead into lakes ...

encompassing large parts of southwestern

Afghanistan Afghanistan, officially the Islamic Emirate of Afghanistan,; prs, امارت اسلامی افغانستان is a landlocked country located at the crossroads of Central Asia and South Asia. Referred to as the Heart of Asia, it is borde ...

and minor parts of southeastern

Iran Iran, officially the Islamic Republic of Iran, and also called Persia, is a country located in Western Asia. It is bordered by Iraq and Turkey to the west, by Azerbaijan and Armenia to the northwest, by the Caspian Sea and Turkmeni ...

, one of the driest regions in the world and an area subjected to prolonged

drought A drought is defined as 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, an ...

s. Its

watershed Watershed is a hydrological term, which has been adopted in other fields in a more or less figurative sense. It may refer to: Hydrology * Drainage divide, the line that separates neighbouring drainage basins * Drainage basin, called a "watershe ...

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. Although the term specifically excludes seawater and brackish water, it does incl ...

lake A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much large ...

s and

marsh A marsh is a wetland that is dominated by herbaceous rather than woody plant species.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p Marshes can often be found ...

es and then to its ultimate destination: Afghanistan's saline Godzareh depression, part of the extensive Sistan terminal basin. The

Helmand River The Helmand River (also spelled Helmend, or Helmund, Hirmand; Pashto/ Persian: ; Greek: ' (''Etýmandros''); Latin: ') is the longest river in Afghanistan and the primary watershed for the endorheic Sistan Basin. It emerges in the Sanglak ...

drains the basin's largest

, fed mainly by

snowmelt In hydrology, snowmelt is surface runoff produced from melting snow. It can also be used to describe the period or season during which such runoff is produced. Water produced by snowmelt is an important part of the annual water cycle in many p ...

from the mountains of

Hindu Kush The Hindu Kush is an mountain range in Central and South Asia to the west of the Himalayas. It stretches from central and western Afghanistan, Quote: "The Hindu Kush mountains run along the Afghan border with the North-West Frontier Province ...

, but other rivers contribute also. A

basalt Basalt (; ) is an 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 surface of a rocky planet or moon. More than 90 ...

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 Iran and Afghanistan. It receives water from the Parian branch of Helmand River, the Farah River and the Harut River.

Hamun-e Helmand

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 ecosystem that is flooded or saturated by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (Anoxic waters, anoxic) processes prevailing, especially in t ...

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 domesticated animals raised in an agricultural setting to provide labor and produce diversified products for consumption such as meat, eggs, milk, fur, leather, and wool. The term is sometimes used to refer solely to ani ...

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

handicraft A handicraft, sometimes more precisely expressed as artisanal handicraft or handmade, is any of a wide variety of types of work where useful and decorative objects are made completely by one’s hand or by using only simple, non-automated re ...

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 An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syste ...

, causing damage to the

agriculture Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people ...

in the delta 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 scientific study of human activity through the recovery and analysis of material culture. The archaeological record consists of artifacts, architecture, biofacts or ecofacts, sites, and cultural landscap ...

sites. The Shahr-i Sokhta, 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 Shahdad ( fa, شهداد, also Romanized as Shahdād; formerly, Khabīs) is a city and capital of Shahdad District, in Kerman County, Kerman Province, Iran. At the 2006 census, its population was 4,097, in 1,010 families. District Shahdad is t ...

, located further to the west, on the western side of

Lut desert The Lut Desert, widely referred to as Dasht-e Lut ( fa, دشت لوت, "Emptiness Plain"), is a large salt desert located in the provinces of Kerman and Sistan and Baluchestan, Iran. It is the world's 33rd-largest desert, and was included on U ...

, is a related site from the Bronze Age. Kang and

Zaranj Zaranj or Zarang ( Persian/Pashto/ bal, زرنج) is a city in southwestern Afghanistan, near the border with Iran, which has a population of 160,902 people as of 2015. It is the capital of Nimruz Province and is linked by highways with Lashkarga ...

in Afghanistan were major

medieval In the history of Europe, the Middle Ages or medieval period lasted approximately from the late 5th to the late 15th centuries, similar to the post-classical period of global history. It began with the fall of the Western Roman Empire a ...

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 f ...

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 with water. Silt usually has a floury feel ...

and agricultural fields buried by shifting

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

. Today the area is sparsely populated. Excavations have also revealed a citadel complex, and the remains of a

Zoroastrian Zoroastrianism is an Iranian religion and one of the world's oldest organized faiths, based on the teachings of the Iranian-speaking prophet Zoroaster. It has a dualistic cosmology of good and evil within the framework of a monotheisti ...

fire temple, on Mount Khajeh. There are other important sites in this area. * Dahan-e Gholaman is a major

Achaemenid The Achaemenid Empire or Achaemenian Empire (; peo, wikt:𐎧𐏁𐏂𐎶, 𐎧𐏁𐏂, , ), also called the First Persian Empire, was an History of Iran#Classical antiquity, ancient Iranian empire founded by Cyrus the Great in 550 BC. Bas ...

archaeological site. It is believed to be the capital of the ancient satrapy of Zranka/

Drangiana Drangiana or Zarangiana ( el, Δραγγιανή, ''Drangianē''; also attested in Old Western Iranian as 𐏀𐎼𐎣, ''Zraka'' or ''Zranka'', was a historical region and administrative division of the Achaemenid Empire. This region comprise ...

. * 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