Xinjiang is the largest political subdivision of China—it accounts for more than one sixth of China’s total territory and a quarter of its boundary length. Xinjiang is mostly covered with uninhabitable deserts and dry grasslands, with dotted oases at the foot of Tian Shan, Kunlun Mountains and Altai Mountains. The inhabitable oasis accounts for 9.7% of Xinjiang’s total area by 2015.
Having hot summer and low precipitation, most of Xinjiang is endorheic. Its rivers either disappear in the desert, or terminate in salt lakes (within Xinjiang itself, or in neighboring Kazakhstan), instead of running towards an ocean. The northernmost part of the region , with the Irtysh River rising in the Altai Mountains, that flows (via Kazakhstan and Russia) toward the Arctic Ocean, is the only exception. But even so, a significant part of the Irtysh’s waters were artificially diverted via the Irtysh–Karamay–Ürümqi Canal to the drier regions of southern Dzungarian Basin.
Elsewhere, most of Xinjiang’s rivers are comparatively short streams fed by the snows of the several ranges of the Tian Shan. Once they enter the populated areas in the mountains’ foothills, their waters are extensively used for irrigation, so that the river often disappears in the desert instead of reaching the lake to whose basin it nominally belongs. This is the case even with the main river of the Tarim Basin, the Tarim, which has been dammed at a number of locations along its course, and whose waters have been completely diverted before they can reach the Lop Lake. In the Dzungarian basin, a similar situation occurs with most rivers that historically flowed into Lake Manas. Some of the salt lakes, having lost much of their fresh water inflow, are now extensively use for the production of mineral salts (used eg, in the manufacturing of potassium fertilizers); this includes the Lop Lake and the Manas Lake.
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