Arghandab is a river in Afghanistan

Afghanistan

Afghanistan , officially the Islamic Republic of Afghanistan, is a landlocked country located in the centre of Asia, forming South Asia, Central Asia and the Middle East. With a population of about 29 million, it has an area of , making it the 42nd most populous and 41st largest nation in the world...

, about 400 kilometres (248.5 mi) in length. It rises in the Hazarajat

Hazarajat

The Hazarajat is the original homeland of the Hazara people, and lies in the central highlands of Afghanistan, among the Koh-i-Baba mountains and the western extremities of the Hindu Kush. Its physical boundaries, however, are roughly marked by the Bamiyan Basin to the north, the headwaters of...

 country north-west of Ghazni

Ghazni

For the Province of Ghazni see Ghazni ProvinceGhazni is a city in central-east Afghanistan with a population of about 141,000 people...

, and flows south-west falls into the Helmand

Helmand River

The Helmand River is the longest river in Afghanistan and the primarily watershed for the endorheic Sistan Basin....

 30 km (18.6 mi) below Girishk

Girishk

Girishk is a village and fort of Afghanistan. It stands on the right bank of the Helmand River 78 miles west of Kandahar on the road to Herat; 3641 ft. above the sea. Girishk was occupied by the British during the First Afghan War, and a small garrison of sepoys under a native officer successfully...

. In its lower course it is much used for irrigation, and the valley is cultivated and populous; yet the water is said to be somewhat brackish. It is doubtful whether the ancient Arachotus is to be identified with the Arghandab or with its chief confluent the Tarnak

Tarnak

Tarnak may refer to:*Tarnak River, Afghanistan*Tarnak Wa Jaldak District, Afghanistan*Tarnak Farms, Afghanistan...

, which joins it on the left out 50 km (31.1 mi) SW of Kandahar

Kandahar

Kandahar is the second largest city in Afghanistan, with a population of about 512,200 as of 2011. It is the capital of Kandahar Province, located in the south of the country at about 1,005 m above sea level...

. The two rivers run nearly parallel. The Tarnak is much shorter (length about 320 km or 200 miles) and less copious. The ruins at Ulan Robat, supposed to represent the city Arachosia

Arachosia

Arachosia is the Latinized form of the Greek name of an Achaemenid and Seleucid governorate in the eastern part of their respective empires, around modern-day southern Afghanistan. The Greek term "Arachosia" corresponds to the Iranian land of Harauti which was between Kandahar in Afghanistan and...

, are in its basin; and the lake known as Ab-i-Istada, the most probable representative of Lake Arachotus, is near the head of the Tarnak, though not communicating with it. The Tarnak is dammed for irrigation at intervals, and in the hot season almost dries up.

There is a good deal of cultivation along the river, but few villages. The high road from Kabul

Kabul

Kabul , spelt Caubul in some classic literatures, is the capital and largest city of Afghanistan. It is also the capital of the Kabul Province, located in the eastern section of Afghanistan...

 to Kandahar passes this way (another reason for supposing the Tarnak to be Arachotus), and the people live off the road to avoid the onerous duties of hospitality.

In 2008 a project was initiatated to rehabilitate the Dahla Dam

Dahla Dam

The Dahla Dam is the largest dam in Kandahar Province, and the second largest in Afghanistan.The dam is 34 kilometers north of Kandahar City.The dam was first built between 1950 to 1952 during the reign of Zahir Shah, the last King of Afghanistan....

, and associated irrigation system.