The Sistan basin, at c.470 m on the border between Iran and Afghanistan, contains a complex of freshwater lakes with extensive reedbeds which at times of peak flooding can cover over 200,000 ha. These wetlands are unusual in that the three main lakes, Hamoun-i Puzak (see site 088), Hamoun-i Sabari and Hamoun-i Hirmand, are predominantly freshwater despite lying within an internal drainage basin. The system lies in an extremely arid region, and receives the great bulk of its water from the Hirmand (Helmand), Fara and several other smaller rivers rising in the highlands of central and northern Afghanistan. During long droughts, as in the late 1960s and mid-1980s, these rivers supply sufficient water to flood only the uppermost of the lakes, Hamoun-i Puzak, which lies almost entirely within Afghanistan. However, during years of unusually heavy rain, as in the late 1970s and 1989-1991, the floodwaters sweep through all three lakes and overflow into a vast salt waste to the south-east, flushing the salts out of the system in the process. The Hamoun-i Sabari (31°20'N 61°20'E; up to 101,300 ha), about half of which lies in Iran, receives water from the Fara Rud, which enters in the north-east (in Afghanistan), and overflow from the Hamoun-i Puzak to the east. The Hamoun-i Hirmand (30°50'N 61°15'E; up to 65,600 ha) receives water from the southern (Sistan) branch of the Hirmand and overflow from the Hamoun-i Sabari to the north. During flooding, both lakes support extensive growths of Phragmites, Typha, Carex and Tamarix, as well as abundant submerged aquatic vegetation, but very little emergent growth has re-appeared since the drought of the early and mid-1980s. Other habitats include extensive mudflats, saltmarshes and bare saltflats. The wetlands are bordered to the east and south by vast desertic plains, those to the south consisting of extensive bare saltflats and sparsely vegetated sandy plains with dune areas and some Tamarix scrub. In the west, the hamouns are bounded by a line of low earth cliffs at the edge of a vast undulating desert plain. An isolated flat-topped volcanic plug (Kuh Khvajeh) rises abruptly out of the marshes to 609 m on the east side of Hamoun-i Hirmand and has a ruined settlement of considerable archaeological interest. Much of the land around Zabol and its many satellite villages east of the hamouns is under irrigated cultivation. Livestock grazing, reed-cutting and fishing occur in the wetlands, and in recent years the lakes have been stocked with grass carp Ctenopharyngodon idella. The land is publicly owned.
See box for key species. The wetlands are extremely important as a staging and wintering area for a wide variety of waterbirds, notably pelicans, herons, dabbling ducks and shorebirds, and in years of high water level are also important for many breeding species. Comprehensive ground and aerial censuses between 1969/70 and 1975/76 indicated that numbers of ducks and geese wintering in the Iranian portion of the Sistan wetlands varied from almost nil in exceptionally dry years (e.g. 1970/71) to over 700,000 in wet years (e.g. 1972/73). There has been a dramatic decline in numbers since then, and this has been attributed to the prolonged drought of the early and mid-1980s and large-scale degradation of the aquatic vegetation. The lush vegetation around the wetlands provides a staging area for large numbers of migratory landbirds, while the surrounding deserts support a typical desert avifauna. Other notable species include Circus aeruginosus (over 15 pairs breeding), Aquila clanga, Falco pelegrinoides, Porphyrio porphyrio, Pterocles senegallus, Bubo bubo, Caprimulgus aegyptius, Melanocorypha bimaculata, Ammomanes cincturus, Alauda gulgula, Motacilla citreola and Sylvia nana. Phylloscopus trochiloides nitidus has occurred on autumn passage. At least 170 species have been noted at the site.
The western half of the Hamoun-i Sabari and Hamoun-i Hirmand and a large area of desert to the west were designated the Hamoun Protected Region in 1967, and the boundaries were revised in 1969 to give an area of 201,062 ha. The reserve was reduced to 193,500 ha in the early 1970s, and upgraded to Wildlife Refuge. It has since been downgraded to Protected Area, and this includes only the main open water areas of the two lakes and their western shorelines, and excludes the important marshes in the east. The Iranian portion of the Hamoun-i Sabari and the northern section of the Hamoun-i Hirmand were designated a Ramsar Site of c.50,000 ha in 1975, c.37,000 ha of which lies within the Hamoun Protected Area. In the mid-1970s, considerable progress was made with a proposal to extend the boundaries of the Hamoun Wildlife Refuge eastwards to incorporate the whole of the Hamoun-i Sabari and Hamoun-i Hirmand wetlands (including Kuh Khvajeh), as well as the Iranian portion of the Hamoun-i Puzak, and indeed the proposed boundaries have appeared on Department of the Environment maps. However, the new boundaries were never formally gazetted, and the Hamoun Protected Area remains in its original form (apart from a minor boundary change in 1969). Extension of the reserve to incorporate the whole of the wetland area (and Ramsar Site) remains highly desirable.
Irrigation schemes on the Hirmand river in both Afghanistan and Iran have reduced the flow into the hamouns, and consequently the wetlands fill completely only in very wet years and are more prone to drying out in summer. Many of the problems of drought in the Sistan basin have been attributed to dam construction and water diversion on the Hirmand in Afghanistan. The Kajaki Dam, built c.40 years ago, was increased in capacity c.20 years ago and undoubtedly caused a considerable reduction in water reaching the hamouns, especially during dry years. However, according to recent reports from FAO in Islamabad, the exceptional floods of early 1991 destroyed the Kajaki Dam and damaged other irrigation systems on the Hirmand in Afghanistan, so for the present there seems to be no problems of water supply in the Hirmand river -- though there is apparently a proposal to build a new dam in Afghanistan (the Kamal Khan Dam).
Despite high water levels and prolonged flooding in the Hamoun-i Sabari and much of the Hamoun-i Hirmand each year since 1989, there was still an almost complete absence of emergent aquatic vegetation by early 1992. This contrasts markedly with the early 1970s, when the aquatic vegetation recovered almost immediately after the severe drought of 1970/71 (when all of the wetlands on the Iranian side of the border were completely dry). The reasons for the present lack of vegetation are unclear. It has been argued that the length of the drought in the early 1980s is the principal cause (some parts of the Hamoun-i Hirmand remained dry for six years), and the digging up of tubers for fuel may also have contributed. Another possible cause is the massive stocking of the lakes in recent years with herbivorous fish. The voracious Ctenopharyngodon idella (grass carp) was introduced about 1988, and now supports a major fishery. Introductions continue, with some two million fish released into the Hamoun-i Hirmand in 1992. The lack of emergent vegetation is of considerable concern to local people, who depend on the marsh for grazing cattle and water buffalo. Very few livestock are now present around the Hamoun-i Hirmand and Hamoun-i Sabari, most having been moved to the Hamoun-i Puzak marshes on the Afghan border.
An asphalt highway is currently being constructed across the low-lying flats between the north end of the Hamoun-i Hirmand and the south end of the Hamoun-i Sabari, passing through the middle of the Ramsar Site and the Hamoun Protected Area. The road incorporates several bridges, but water flow between the two hamouns has been impeded to some extent, with unknown effects on their hydrology and ecology. A canal recently constructed between the south end of the Hamoun-i Puzak and the Hamoun-i Sabari, to accelerate the flow of water into the Sabari, will also have a major impact on the hydrology.
Data-sheet compiled by Dr D. A. Scott, reviewed by Dept of Environment.
BirdLife International (2021) Important Bird Areas factsheet: Hamoun-i Sabari and Hamoun-i Hirmand. Downloaded from
http://www.birdlife.org on 23/10/2021.