新疆降水特征及其对水资源和生态环境的影响

新疆位于欧亚大陆腹地,空中水汽来源少,水资源匮乏,生态环境脆弱,降水有其独特的时空分布特征,且对水资源形成和生态环境有着十分重要的影响和作用.利用全疆106处水文、气象站1956-2005年的降水资料以及相关分析研究成果,从水资源的角度对新疆降水的形成条件、时空分布特征和对水资源、生态环境的影响进行了分析.结果表明:多年平均年降水总量为2588×10⁸m³,折合降水深157.4 mm;90%以上的站点年降水量变差系数在0.2～0.7之间;连续最大4个月降水量在40%以上,平均降水产流系数为34%.新疆降水的稀少导致了其生态环境的极端脆弱,绿洲面积仅占全疆总面积的9%,而沙漠面积却达全疆的25.7%.未来新疆地区仍然是干旱、半干旱地区,大气降水资源有限,必须通过其它途径来解决新疆水资源短缺问题.

Precipitation and Its Impact on Water Resources and Ecological Environment in Xinjiang Region

The Xinjiang Uygur Autonomous Region is located in the hinterland of the Eurasian continent and away from the sea.Precipitation in the region is scarce and its temporal and spatial temporal distributions are uneven.The mean annual precipitation is 2588×10⁸ m³,which is equivalent to 157.4 mm water deep.The characteristics of geographical distribution of precipitation are as follows: precipitation in the north is more than that in the south;precipitation in the northwest is more than that in the southeast;precipitation in the windward slopes is more than that in the leeward slopes;precipitation in the mountain areas is more than that in the plains and basins.Zonal vertical distribution of precipitation is obvious.The changing range of annual precipitation in the north is less than that in the south.The coefficients of variation of annual precipitation at more than 90% of the stations are between 0.2 and 0.7.From May to August there is a high consecutive rainfall period.The intensity of precipitation is small in north but great in the south.The relative intensity at higher altitude is generally greater that that in lower altitude.The longest continuous dry season is 3~5 months in the south slopes of Altay Mountains,the mountains west of the Junggar Basin and the western Tianshan Mountains,5~7 months along the north slopes of Tianshan Mountains and 6~8 months in the south region,east region and the Junggar Basin.;The atmospheric precipitation,the river runoff and the surface water resources in Xinjiang Region are related well.For example,the correlation coefficient of precipitation and surface water resources is 0.8290.The flow coefficient of average precipitation is 0.34 in all Xinjiang Region,and the areas with abundant precipitation are larger than those with short precipitation.Sparse rainfall results in extreme vulnerability of the ecological environment in the region.The coverage rate of forest is only 1.5%,the total oasis area is less than 9% and the total desert area is 25.7% in the region.The precipitation factor is 0.25 and is the largest one among the weight factors of vulnerability assessment of ecological environment in Xinjiang Region.;Simulation results of global climate models show that Xinjiang Region will still be arid,semi-arid areas in the future.The water resources of atmospheric precipitation are very limited,so it is unrealistic to rely on rainfall to ease the shortage of water resources in the region.In order to economic and social sustainable development,the problem of water resources of Xinjiang Region must be dealt with by other means,such as rational allocation and utilization of water resources,using various types of water-saving techniques and enhancing the public’s awareness of water-saving etc.