Freshwater Fishes of Iran
Introduction - Drainage Basins - Yazd
The Yazd basin extends from Ardestan (33°22'N, 52°23'E) in the north-west to Kerman (30°17'N, 57°05'E) in the south-east. It is an elongate series of small basins combined here for convenience and named for Yazd (31°53'N, 54°25'E) in the centre. It has been called formerly the Kerman-Na'in basin by Saadati (1977) and in various papers by me. Its length exceeds 600 km and its maximum width is 175 km. An almost continuous range of mountains, paralleling the Zagros, flanks this basin on the west, while the eastern edge is lower and abuts the Kavir and Lut basins, particularly in the north-east. The Yazd basin lies at a similar altitude to the other interior basins, ca. 1000 m.
In the south-east, streams drain the mountains ringing Kerman, such as the Kuh-e Hazaran at 4420 m (29°30'N, 57°18'E), the Kuhpayeh at 3142 m (30°35'N, 57°15'E), and the Kuh-e Masahim at 3600 m (30°21'N, 55°20'E), to a sump just west of Bafq (31°35'N, 55°24'E). These streams bear names such as Namak and Shur and may well be inhospitable to fishes. Several streams between Kerman and Yazd marked prominently on maps were dry in January. Irrigation requirements may have reduced their flow and most of the fishes from this area are to be found in qanats. Qanats have temperatures in this region of 17-21°C in January and have been studied in one village by Smith (1953; 1979).
Around Yazd streams drain the Shir Kuh at 4074 m (31°37'N, 54°04'E) and the Khar Kuh at 3512 m (31°39'N, 53°46'E) but there is no major terminal sump. Some of the streams enter the Bafq sump while others drain north to a sump near Na'in (32°52'N, 53°05'E) which also receives intermittent streams from around Na'in.
Intermittent streams from the Kuh-e Karkas at 3899 m (33°27'N, 51°48'E) drain to a sump near Ardestan but, as in the southern parts of this basin, are not a prominent feature of the landscape and fishes are mostly to be caught in qanats.
The underground water resources of Yazd Province have been examined in a newspaper article (Hamshahri, Tehran, 629:5, 22 February 1995) and, although the province is not the same area as the drainage basin outlined here, it is indicative of the underground water resources of this part of Iran. These resources comprise 1751 subterranean water canals (probably this means qanats), 2084 semi-deep wells and 897 deep wells with an annual discharge of 1100 million cu m of underground water. The authorised capacity is 893 million cu m and the excess removal has resulted in an annual drop in the water table of 70 cm. In addition, chemical and biological pollution of groundwater is a continuing problem and these factors too will affect fish survival.
Much of the fish fauna of the Yazd basin appears to be restricted to qanats, although there may be a fauna in high mountain streams not readily accessible by road.
© Brian W. Coad (www.briancoad.com)