The arid zone of northwest China is located in the mid-latitude area of Eurasia Hinterland. It is the most developed mountain system in Central Asia. Its Rivers which originate in its mountainous areas are formed mainly from glaciers, snowmelts, and precipitation. Global warming has intensified the water cycle making climate change in this particular region complex and volatile, Specifically, the changes in air temperatures and precipitation have significantly impacted surface water resources
The convergence of the rivers in the arid region of northwest China supply the surface water resources to areas such as Sichuan and the Zhongshan forest zone. Usually, the water resources maintain a fragile balance by relying on the unique, natural water cycle. However, due to the impact of global warming the water system’s vulnerability has increased.
global warming has increased the hydrological fluctuation and uncertainty of the water resources in the inland river basin . (1) There is in fact, a “mutation type change” increase in runoff. Rivers with large amounts of glacier melt-water recharge such as the Kaidu in southern Xinjiang, generally experiences a primary runoff increase which began around 1994. Comparing annual increases of water levels, elevations in the Kaidu river basin in southern Xinjiang are higher by 26.5% than that from 1960 to 1993[3] (2) Years of analyses reveal that snow and glacial-melting contribute to rising water levels in large rivers during the ice and snow melt periods. Rising water levels in the Tarim river basin for example, show an increase of 46.5% in 1991 to 2006 from 41.5% in 1961-1990 [4]. Changes in runoff intensified.
Climate change in the continental river basin has exacerbated the fluctuations of hydrological and water resources. The uncertainty in the arid northwest areas proves that every stage of the water cycle is significantly influenced by the patterns of epicontinental climate changes. Water resources constitute a complex runoff and water elasticity is greatly impacted. Additionally, precipitation extremes and temperature changes caused by climate change will significantly alter the ecological and hydrological processes in arid areas. The effects of climate change on water circulation in the mountainous areas have intensified the instability of the water system.
China’s desert expansion has been a serious issue for half a century. Desert regions have grown by more than 285,000 square miles. The rate of the rise in temperatures in the northwest arid region is as high as 0.34oC /10a, which is significantly higher than the global average of (0.12oC /10a)[1]. Records indicate a sharp rise in temperatures in the late 1980s: compared to the period 1960-1986, the annual average amplitude and increases in temperature show a “mutation type” increase of 0.517oC every 10 years. As for increases in precipitation extremes, the average annual increase rate is 9.7mm/10a.
Due to global warming, the water resource system in the northwest region of China which gets its supply from the mountains, precipitation, and snowmelts is more fragile. Human activities are strongly changing the natural water circulation process of the basin. As for the changes in water resources caused by global warming: water resources are the key factors restricting the social and economic development, and affecting the ecological security in the region. It is necessary to actively cope with and adapt to the possible impacts of future climate change, especially on water resources.
References:
[1] IPCC. Working Group I Contribution to the IPCC Fifth Assessment Report, Climate Change 2013: The Physical Science Basis: Summary for Policymakers.
[2] Chen Y N, Deng H J, Li B F et al. Abrupt change of temperature and precipitation extremes in the arid region of Northwest China. Quaternary International, 2014, 336: 35-43.
[3] Chen Yaning, Du Qiang, Chen Yuebin et al. Sustainable Water Resources Utilization in Bosten Lake Basin. Beijing:Science Press, 2013: 45-74.
[4] Gao Xin, Ye Bosheng, Zhang Shiqiang et al. Glacier runoff variation and its influence on river runoff during 1961-2006 in the Tarim River Basin, China. Science in China: Earth Sciences, 2010, 40(5): 654-665
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