开都河灌区灌溉引水对博斯腾湖面积影响的定量分析

Quantitative Analysis of the Impact of Irrigation Water from Kaidu River on the Area Change of Bosten Lake

开都河是注入博斯腾湖的最大河流,1958～2002年间平均入湖水量达23.62×108m3,占博斯腾湖总补给量的80%以上。1958年以来开都河灌区灌溉引水量维持在8.17×108m3～13.18×108m3之间,其中20世纪60年代灌溉引水量平均为10.14×108m3/a,占开都河径流量的31.1%;70年代引水量上升到12.15×108m3/a,为开都河径流量的36.5%;80年代引水量下降到11.29×108m3/a,但引水量仍占开都河径流量的36.5%;90年代灌溉引水量进一步降至9.85×108m3/a,仅占径流量的27.1%。通过水量平衡分析和相关回归计算,得出开都河灌区灌溉引水对博斯腾湖面积影响的数值:20世纪60年代平均值为62.4km2;70年代平均值为80.8km2;80年代、90年代分别为90.4km2、76.7km2,2000年以来平均仅为41.3km2。由此可见,45年来开都河灌区灌溉引水对博斯腾湖面积的影响经历了弱→强→弱的变化过程。

Bosten Lake is the largest lake in Xinjiang and also the largest inland freshwater lake in China,which lies in the southeast of Yanqi Basin (41°56′～42°14′N,86°40′～87°56′E) and be-longs to the arid desert climate.It is of great value in environment,ecology and economy.The tre-mendous changes in the area of Bosten Lake have been seen in recent 45 years,and its area decreased from 1 159.9km2 in 1958 to 886.5km2 in 1987,and then increased to 1251.1km2 in 2002. Kaidu River is the longest river which flows into Bosten Lake,and its average runoff rea-ched 23.62×108m3/a during 1958 to 2002,accounting for over 80% of the recharge of Bosten Lake.Therefore the water area of Bosten Lake is chiefly controlled by the runoff volume of Kaidu River,and also affected by the amount of water diverted from Kaidu River Irrigation Area (KRIA).The quantity of the water diversion from KRIA ranging from about 8.17×108m3 to 13.18×108m3 has been witnessed in recent 45 years.The average amount of irrigation water reached 10.14×108m3/a in the 1960s,making up 31.6% of the runoff of Kaidu River,and went up to 12.15×108m3/a in the 1970s,or 36.5% of Kaidu River's runoff.The average amount decreased to 11.29×108m3/a in the 1980s and further declined to 9.85×108m3/a in the 1990s,only accounting for 27.1% of the runoff of Kaidu River. Based on the analysis of water balance and the calculation of correlation and regression,the data on the area change of Bosten Lake influenced by the amount of the irrigation water of KRIA are obtained.The average amount reached 62.4km2 in the 1960s,80.8km2 in the 1970s,90.4km2 in the 1980s,and 76.7km2 in the 1990s,but only 41.3km2 since 2000.Those data show that the impact of irrigation water from KRIA on the area change of the Bosten Lake has undergone a weak to strong and then weak process in the past 45 years.