Shule River

Shule Changma
Headwaters of the Shule river
Map of the Shule River drainage basin
Native name	疏勒河 (Shūlè Hé), 昌马河 (Chāngmǎ Hé) Error {{native name checker}}: parameter value is malformed (help)
Location
Country	China
State	Qinghai, Gansu, Xinjiang
Cities	Yuanquan, Dunhuang
Physical characteristics
Source	An unnamed glacier
• location	Qilian Shan, Qinghai
• coordinates	38°14′39″N 98°51′45″E
• elevation	5,000 m (16,000 ft)
Mouth	Lop Nur basin
• location	Kumtag Desert, Xinjiang
• coordinates	40°01′27″N 90°50′52″E
• elevation	789 m (2,589 ft)
Length	770 km (480 mi)
Basin size	102,300 km2 (39,500 sq mi)(Contributing area only about 20,197 km2/7,798 mi2)
Discharge
• location	Changma Reservoir
• average	28.8 m3/s (1,020 cu ft/s)
• minimum	0 m3/s (0 cu ft/s)
• maximum	1,620 m3/s (57,000 cu ft/s)
Basin features
River system	Taklamakan Desert basin
Tributaries
• left	Lucao River, Dang River

The Shule River is a river of the northern Tibetan Plateau and Hexi Corridor of northwestern China. It starts in the Qilian Mountains and flows north then west for about 770 kilometres (480 mi). Historically, the river flowed seasonally into Lop Nur, an intermittent salt lake in the Taklimakan Desert. Due to large irrigation diversions and the gradual desertification of the region, the river dries up about two-thirds of the way along its course in the Kumtag Desert.

Course

It rises as glacier melt in a valley on the northern side of the Qilian Mountains or Nan Shan, on the Tibetan Plateau of extreme northern Qinghai province. In its upper third the river flows generally NNW through deep, glacier-carved valleys and precipitous gorges into Gansu Province, and is known as the Changma. It comes out of the mountains in Guazhou County, and spreads onto a massive inland delta or alluvial fan. Now known as the Shule proper, the river turns due west into an agricultural valley, where most of its water is taken away for irrigation and industrial use. North of Dunhuang, the largest city in the river's basin, it disappears into the desert. The dry river channel stretches about 100 kilometres (62 mi) further WSW to the seasonal Lop Nur basin, which comprises intermittent salt flats, playas and marshes.

Watershed

Satellite view of the Shule River delta

Geography

The Shule's drainage basin covers about 102,300 km² (39,500 sq mi) of land, with only 20,197 km² (7,798 sq mi) contributing significant water flow. There are many other valleys and basins that would drain into the river during extreme floods, but because of the aridity of the region, high flow events are rare. The average precipitation in the watershed is 200 to 300 mm (7.9 to 11.8 in) per year. In the high mountain areas it can be up to 800 mm (31 in), mostly in the form of snow. In the deserts to the north annual precipitation is usually below 100 mm (3.9 in) and in some years, no rain falls at all.

Most of the Shule's water arises from glaciers. There are 347 glaciers in the upstream catchment area of the river encompassing a total area of 29.45 km² (11.37 sq mi). The annual runoff is approximately 1.083 km³ (878,000 acre⋅ft), ranging from a low of 0.536 km³ (435,000 acre⋅ft) to a high of 1.507 km³ (1,222,000 acre⋅ft). Warming temperatures are reducing the size of glaciers feeding the river and may lead to future reductions in water flow.

River modifications

The river valley is intensely cultivated and its flow is regulated by two reservoirs, Changma and Shuangta. There are also more than three additional hydropower/diversion dams on the river. The entire flow of the Shule is diverted directly downstream of the mountains into a canal that runs north-northeast across the delta, supplying farms in the valley to the north. This water is eventually returned to the river, but irrigation usage has caused the river to dry up well before its historic terminus. It is surmised that a few thousand years ago, the region was cooler and wetter, and the river had significantly more flow than it does today.

See also

• List of rivers of China
• Ruo Shui
• Tarim River