The greater portion of the province is a lowland region extending inland from the sea to the base of the mountains of the Elburz range and, though the Sefid Rud (White river), which is called Kizil Uzain in its upper course and has its principal sources in the hills of Persian Kurdistan, is the only river of any size, the province is abundantly watered by many streams and an exceptionally great rainfall (in some years 50 in.).
In the early spring the existence of a lake could only be certified by pools or hollows of water formed at the mouths of the principal feeders, such as the Khash Rud on the north-east, the Farah Rud on the north-west, and the Helmund, where its old bed terminates at no great distance from the Khash Rud.
From its source to Obeh the Hari Rud is a valley of sandy desolation.
The Kabul river drains Northern Afghanistan, the Hari Rud the province of Herat, and the Oxus that of Afghan Turkestan.
On the south of the plateau we find a similar succession of narrow valleys dividing parallel flexures, or anticlinals, formed under similar geological conditions to those which appear to be universally applicable to the Himalaya, the Hindu Kush, and the Indus frontier mountain systems. From one of these long lateral valleys the Hari Rud receives its principal tributary, which joins the main river below Obeh, 180 m.
From its source; and it is this tributary (separated from the Hari Rud by the narrow ridges of the Koh-i-Safed and Band-iBaian) that offers the high road from Herat to Kabul, and not the Hari Rud itself.
The Seafid Rud rises in Persian Kurdistan in about 35 50 N.
From this point to Zulfikar the Hari Rud is itself the boundary.
The geographical divisions of the country are created by the basins of its chief rivers, the Kabul, the Helmund, the Hari Rud and the Oxus.
The dominant mountain system of Afghanistan is the Hindu Kush, and that extension westwards of its water-divide which is indicated by the Koh-i-Baba to the north-west of Kabul, and by the Firozkhoi plateau (Karjistan), which merges still farther to the west by gentle gradients into the Paropamisus, and which may be traced across the Hari Rud to Mashad.