The Shule River flows generally westwards through the Tibetan Plateau

Tibetan Plateau

The Tibetan Plateau , also known as the Qinghai–Tibetan Plateau is a vast, elevated plateau in Central Asia covering most of the Tibet Autonomous Region and Qinghai, in addition to smaller portions of western Sichuan, southwestern Gansu, and northern Yunnan in Western China and Ladakh in...

 and the desert regions of northwestern China

China

Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...

. It starts in the Qilian Mountains and stretches for some 900 kilometres (559.2 mi); however, the river dries up about two-thirds of the way along its course and is lost in the Kumtag Desert

Kumtag Desert

The Kumtag Desert, Kumtagh Desert or Desert of Kum-tag , literally "sand mountain desert" in Old Turkic language , is an arid landform in Northwestern China, which was proclaimed as a national park in the year 2002.-Definitions:1...

, an endorheic basin, meaning its water never reaches the sea. Historically, the river reached farther west to Lop Nur

Lop Nur

Lop Lake or Lop Nur is a group of small, now seasonal salt lake sand marshes between the Taklamakan and Kuruktag deserts in the Bayingolin Mongol Autonomous Prefecture, southeastern portion of Xinjiang Uygur Autonomous Region in the People's Republic of China.The lake system into which the Tarim...

, an intermittent salt lake in the Taklimakan Desert. Large irrigation

Irrigation

Irrigation may be defined as the science of artificial application of water to the land or soil. It is used to assist in the growing of agricultural crops, maintenance of landscapes, and revegetation of disturbed soils in dry areas and during periods of inadequate rainfall...

 diversions off the river and the gradual desertification

Desertification

Desertification is the degradation of land in drylands. Caused by a variety of factors, such as climate change and human activities, desertification is one of the most significant global environmental problems.-Definitions:...

 of the region have reduced its flow significantly.

Course

It rises as several streams in a valley on the northern side of the Qilian Mountains or Nan Shan, on the Tibetan Plateau

Tibetan Plateau

The Tibetan Plateau , also known as the Qinghai–Tibetan Plateau is a vast, elevated plateau in Central Asia covering most of the Tibet Autonomous Region and Qinghai, in addition to smaller portions of western Sichuan, southwestern Gansu, and northern Yunnan in Western China and Ladakh in...

 of extreme northern Qinghai

Qinghai

Qinghai ; Oirat Mongolian: ; ; Salar:) is a province of the People's Republic of China, named after Qinghai Lake...

 province. In its upper 310 kilometres (192.6 mi) the river flows generally NNW through deep, glacier-carved valleys and precipitous gorges into Gansu

Gansu

' is a province located in the northwest of the People's Republic of China.It lies between the Tibetan and Huangtu plateaus, and borders Mongolia, Inner Mongolia, and Ningxia to the north, Xinjiang and Qinghai to the west, Sichuan to the south, and Shaanxi to the east...

 Province, and is known as the Changma. It comes out of the mountains in Guazhou County

Guazhou County

Guazhou County , formerly Anxi County , is an administrative district in Gansu, the People's Republic of China. It is one of 58 counties of Gansu...

, and spreads onto a massive inland delta

River delta

A delta is a landform that is formed at the mouth of a river where that river flows into an ocean, sea, estuary, lake, reservoir, flat arid area, or another river. Deltas are formed from the deposition of the sediment carried by the river as the flow leaves the mouth of the river...

 or alluvial fan

Alluvial fan

An alluvial fan is a fan-shaped deposit formed where a fast flowing stream flattens, slows, and spreads typically at the exit of a canyon onto a flatter plain. A convergence of neighboring alluvial fans into a single apron of deposits against a slope is called a bajada, or compound alluvial...

. 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

Dunhuang

Dunhuang is a city in northwestern Gansu province, Western China. It was a major stop on the ancient Silk Road. It was also known at times as Shāzhōu , or 'City of Sands', a name still used today...

, the largest city in the river's basin, it disappears into the desert, after flowing some 540 kilometres (335.5 mi). The dry river channel stretches about 350 kilometres (217.5 mi) further WSW to the seasonal Lop Nur basin, which comprises intermittent salt flats, playas and marshes.

Geography

The Shule's drainage basin covers about 102300 square kilometre of land, but the contributing portions total only 20197 square kilometre. 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 millimetres (31.5 in), mostly in the form of snow. In the deserts to the north annual precipitation is usually below 100 millimetres (3.9 in) and in some years, no rain falls at all. Most of the Shule's flow arises from glaciers. Because of a general warming trend in the region, the glaciers feeding the river could eventually melt completely, causing it to dry up.

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 NNE 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.